Faecal Occult Blood Test: From 1 Different Sources
(FOBT) a noninvasive test used to identify microscopic blood (see occult) in faeces. It is widely used as a screening test for colorectal cancer.
The principal reproductive androgen of males, largely responsible for sexual maturation, some libido, and a range of metabolic reactions that, while supplying short-term strengths, creates a long-term fragility and brittleness if not in balance with less garish but more sustainable metabolic buffers. It is secreted by the Leydig cells of the testes, as well as smaller amounts in the adrenal cortices of both sexes. It is made under the direction of LH from the pituitary, and, if oversecreted, can be inhibited by sperm-producing cells, diminished pituitary support, and a rise in blood levels of its waste-product, stored in adipose tissues...estradiol... testosterone
A blood clot arises when blood comes into contact with a foreign surface – for example, damaged blood vessels – or when tissue factors are released from damaged tissue. An initial plug of PLATELETS is converted to a de?nitive clot by the deposition of FIBRIN, which is formed by the clotting cascade and erythrocytes. (See COAGULATION.)... blood clot
The number of each of the cellular components per litre of blood. It may be calculated using a microscope or by an automated process.... blood count
See TRANSFUSION – Transfusion of blood.... blood transfusion
See SEPTICAEMIA.... blood-poisoning
A skin test to ?nd out if a person is immune to TUBERCULOSIS. TUBERCULIN (a preparation derived from the TUBERCLE bacillus) is injected via punctures in the skin of the forearm, using a spring-loaded gunlike instrument with six very short needles set in circular form. A positive test is indicated by a red raised reaction of the skin: this means that the subject is immune. If the result is negative, the subject can be given BCG VACCINE.... heaf test
A test for TUBERCULOSIS. It consists in injecting into the super?cial layers of the skin (i.e. intradermally) a very small quantity of old TUBERCULIN which contains a protein ANTIGEN to TB. A positive reaction of the skin – swelling and redness – shows that the person so reacting has been infected at some time in the past with Mycobacterium tuberculosis. However, it does not mean that such a person is suffering from active tuberculosis.... mantoux test
Describing something that is not easily seen. Occult blood in the faeces is present in very small amounts and can be identi?ed only by a chemical test or under the microscope.... occult
This is used to identify possible substances that may be causing a patient’s ALLERGY. Small amounts of di?erent substances are placed on the skin – usually of the back or arm. If the patient is allergic then a red ?are and swelling will appear, usually within about 15 minutes. Sometimes the reaction may take longer – up to three days – to develop.... patch test
A psychological test (see PSYCHOLOGY) for investigating personality and disorders of personality. Also called the ‘ink blot test’, it is now rarely used. It was devised by a Swiss psychiatrist, Hermann Rorschach (1884–1922), who determined individuals’ reactions to a series of symmetrical ink-blots, ten in number and standardised by him.... rorschach test
Every man has two testicles or testes which are the sexual glands. In the fetus, they develop in the abdomen, but before birth they descend into a fold or pouch of skin known as the SCROTUM. Each testicle consists of up to 1,000 minute tubes lined by cells from which the spermatozoa (see SPERMATOZOON) are formed. Around 4·5 million spermatozoa are produced per gram of testicle per day. These tubes communicate with one another near the centre of the testicle, and are connected by a much coiled tube, the EPIDIDYMIS, with the ductus, or VAS DEFERENS, which enters the abdomen and passes on to the base of the bladder. This duct, after joining a reservoir known as the seminal vesicle, opens, close to the duct from the other side of the body, into the URETHRA where it passes through the PROSTATE GLAND. Owing to the convolutions of these ducts leading from the testicles to the urethra, and their indirect route, the passage from testicle to urethra is over 6 metres (20 feet) in length. In addition to producing spermotozoa, the testicle also forms the hormone TESTOSTERONE which is responsible for the development of male characteristics.... testicle
See BLOOD GROUPS.... abo blood groups
A department in which blood products are prepared, stored, and tested prior to transfusion into patients.... blood bank
A functional, semi-permeable membrane separating the brain and cerebrospinal ?uid from the blood. It allows small and lipid-soluble molecules to pass freely but is impermeable to large or ionised molecules and cells.... blood brain barrier
See ERYTHROCYTES and LEUCOCYTES.... blood corpuscle
An individual who donates his or her own blood for use in patients of compatible blood group who require transfusion.... blood donor
Speci?cally, this describes the measurement of the tensions of oxygen and carbon dioxide in blood. However, it is commonly used to describe the analysis of a sample of heparinised arterial blood for measurement of oxygen, carbon dioxide, oxygen saturation, pH, bicarbonate, and base excess (the amount of acid required to return a unit volume of the blood to normal pH). These values are vital in monitoring the severity of illness in patients receiving intensive care or who have severe respiratory illness, as they provide a guide to the e?ectiveness of oxygen transport between the outside air and the body tissues. Thus they are both a guide to whether the patient is being optimally ventilated, and also a general guide to the severity of their illness.... blood gases
Removal of venous, capillary or arterial blood for haematological, microbiological or biochemical laboratory investigations.... blood test
Tube through which blood is conducted from or to the heart. Blood from the heart is conducted via arteries and arterioles through capillaries and back to the heart via venules and then veins. (See ARTERIES and VEINS.)... blood vessel
A test for vestibular function (see EAR). It is performed by irrigating the external auditory meatus of the ear with alternate cold and hot water. This usually stimulates the vestibular apparatus, causing nystagmus (see DIABETES MELLITUS – Diabetic eye disease). If the vestibular apparatus is affected by disease, the response may be absent or reduced.... caloric test
People are divided into four main groups in respect of a certain reaction of the blood. This depends upon the capacity of the serum of one person’s blood to cause the red cells of another’s to stick together (agglutinate). The reaction depends on antigens (see ANTIGEN), known as agglutinogens, in the erythrocytes and on ANTIBODIES, known as agglutinins, in the serum. There are two of each, the agglutinogens being known as A and B. A person’s erythrocytes may have (1) no agglutinogens, (2) agglutinogen A, (3) agglutinogen B, (4) agglutinogens A and B: these are the four groups. Since the identi?cation of the ABO and Rhesus factors (see below), around 400 other antigens have been discovered, but they cause few problems over transfusions.
In blood transfusion, the person giving and the person receiving the blood must belong to the same blood group, or a dangerous reaction will take place from the agglutination that occurs when blood of a di?erent group is present. One exception is that group O Rhesus-negative blood can be used in an emergency for anybody.
| Agglutinogens | Agglutinins | Frequency |
| in the | in the | in Great |
| Group | erythrocytes | plasma | Britain |
| AB | A and B | None | 2 per cent |
| A | A | Anti-B | 46 per cent |
| B | B | Anti-A | 8 per cent |
| O | Neither | Anti-A and | 44 per cent |
| A nor B | Anti-B | |
| | | |
Rhesus factor In addition to the A and B agglutinogens (or antigens), there is another one known as the Rhesus (or Rh) factor – so named because there is a similar antigen in the red blood corpuscles of the Rhesus monkey. About 84 per cent of the population have this Rh factor in their blood and are therefore known as ‘Rh-positive’. The remaining 16 per cent who do not possess the factor are known as ‘Rh-negative’.
The practical importance of the Rh factor is that, unlike the A and B agglutinogens, there are no naturally occurring Rh antibodies. However, such antibodies may develop in a Rh-negative person if the Rh antigen is introduced into his or her circulation. This can occur (a) if a Rh-negative person is given a transfusion of Rh-positive blood, and (b) if a Rh-negative mother married to a Rh-positive husband becomes pregnant and the fetus is Rh-positive. If the latter happens, the mother develops Rh antibodies which can pass into the fetal circulation, where they react with the baby’s Rh antigen and cause HAEMOLYTIC DISEASE of the fetus and newborn. This means that, untreated, the child may be stillborn or become jaundiced shortly after birth.
As about one in six expectant mothers is Rh-negative, a blood-group examination is now considered an essential part of the antenatal examination of a pregnant woman. All such Rh-negative expectant mothers are now given a ‘Rhesus card’ showing that they belong to the rhesus-negative blood group. This card should always be carried with them. Rh-positive blood should never be transfused to a Rh-negative girl or woman.... blood groups
A sensitive test that detects ANTIBODIES to the body’s red cells (see ERYTHROCYTE). There are two methods: one – the direct method – identi?es those antibodies that are bound to the cells; the other, indirect, method identi?es those circulating unattached in the serum.... coomb’s test
Skin test used to determine the immune s tatus to scarlet fever.... dick test
A procedure performed during a mother’s labour in which a blood sample is taken from a vein in the scalp of the FETUS. This enables tests to be performed that indicate whether the fetus is, for example, suffering from a shortage of oxygen (HYPOXIA). If so, the obstetrician will usually accelerate the baby’s birth.... fetal blood sampling
A way of assessing the body’s e?ciency at metabolising GLUCOSE. The test is used in the diagnosis of DIABETES MELLITUS. The patient is starved for up to 16 hours, after which he or she is fed glucose by mouth. The concentrations of glucose in the blood and urine are then measured at half-hour intervals over a period of two hours.... glucose-tolerance test
A standardised procedure of mental assessment to determine an individual’s intellectual ability. The result is produced as a score termed the INTELLIGENCE QUOTIENT (IQ). The Wechsler Adult Intelligence Scale (WAIS) and one for children, the Wechsler Intelligence Scale for Children (WICS), are commonly used, as is the Stanford-Binet Scale. Assessments are made for educational purposes and to help in the diagnoses of people with possible mental retardation or intellectual deterioration.... intelligence test
The characteristic histological test used for the diagnosis of SARCOIDOSIS. The test involves an intradermal injection of sarcoid SPLEEN tissue. If positive, non-caseating granulomata (see GRANULOMA) are seen at the injection site in 4– 6 weeks. A positive test is highly speci?c for sarcoid, but if negative, this would not be excluded.... kveim test
See CERVICAL SMEAR.... papanicolaou test
See ERYTHROCYTES; BLOOD.... red blood cell
The screening of apparently healthy people to identify those who may have treatable diseases. Cervical smears are done when screening women to detect if they have cancer or precancer of the neck of the womb (cervix). Newborn babies are screened for hip dislocation. Screening tests are not designed to diagnose individual persons, but rather to divide a population into a large number at low risk and a small number at high risk of a condition. This allows clinicians to concentrate on a sub-section of the population. All screening tests produce false negative and false positive results, a problem often misunderstood by those at the receiving end. Factors to be assessed when planning screening procedures include the severity, frequency and distribution of the disease, and the availability and e?ectiveness of treatment. Convenience, safety, sensitivity and cost should also be assessed. In the United Kingdom the government has supported the extension of screening procedures for breast cancer, cervical cancer, hypertension and diabetes. (See PREVENTIVE MEDICINE.)... screening test
See EMBRYO TRANSFER.... test-tube baby
Most vision tests examine a person’s sharpness of VISION (visual acuity) and often of the ?eld of vision (see VISION, FIELD OF). Refraction tests assess whether a person has an error that can be corrected with glasses such as ASTIGMATISM, HYPERMETROPIA or MYOPIA. Visual acuity is tested using a Snellen chart when the patient tries to read letters of di?ering standard sizes from 6 metres away. The optician will prescribe lenses to correct any defects detected by vision tests.... vision tests
See LEUCOCYTES.... white blood cell
See blood glucose.... blood sugar
A testis that is drawn up.... testis, retractile
See TRANSFUSION – Transfusion of blood.... autologous blood transfusion
A test for gauging the e?ciency of the balancing mechanism (the vestibular apparatus) by applying hot or cold air or water to the external ear.... barany’s test
See VENESECTION.... blood-letting
See ANAEMIA; LEUKAEMIA; LYMPHOMA; MYELOMATOSIS; THROMBOSIS.... blood, diseases of
A medico-legal defence for a clinician accused of failing to provide an acceptable standard of care for one of his or her quali?cation and experience. The defence is that a responsible body of medical practitioners would have taken the same action, even though others would have acted di?erently. The precise size of a ‘responsible body’ has not been de?ned. The test has been modi?ed following a case referred to as Bolitho, in which it was held that the Bolam defence failed if it could be shown that the actions relied upon, although shown to be carried out by some responsible doctors, were nonetheless illogical.... bolam test
In surveys, studying the process of interpretation of questions and the formation and reporting of responses by respondents to learn how to make the questions more accurately obtain the data the questionnaire is seeking.... cognitive testing
Love, Protection, Exorcism, Potency... dragons blood
See GENETIC SCREENING.... gene testing
The course of the circulation is as follows: the veins pour their blood, coming from the head, trunk, limbs and abdominal organs, into the right atrium of the HEART. This contracts and drives the blood into the right ventricle, which then forces the blood into the LUNGS by way of the pulmonary artery. Here it is contained in thin-walled capillaries, over which the air plays freely, and through which gases pass readily out and in. The blood gives o? carbon dioxide (CO2) and takes up oxygen (see RESPIRATION), and passes on by the pulmonary veins to the left atrium of the heart. The left atrium expels it into the left ventricle, which forces it on into the aorta, by which it is distributed all over the body. Passing through capillaries in the various tissues, it enters venules, then veins, which ultimately unite into two great veins, the superior and the inferior vena cava, these emptying into the right atrium. This complete circle is accomplished by any particular drop of blood in about half a minute.
In one part of the body there is a further complication. The veins coming from the bowels, charged with food material and other products, split up, and their blood undergoes a second capillary circulation through the liver. Here it is relieved of some food material and puri?ed, and then passes into the inferior vena cava, and so to the right atrium. This is known as the portal circulation.
The circle is maintained always in one direction by four valves, situated one at the outlet from each cavity of the heart.
The blood in the arteries going to the body generally is bright red, that in the veins dull red in colour, owing to the former being charged with oxygen and the latter with carbon dioxide (see RESPIRATION). For the same reason the blood in the pulmonary artery is dark, that in the pulmonary veins is bright. There is no direct communication between the right and left sides of the heart, the blood passing from the right ventricle to the left atrium through the lungs.
In the embryo, before birth, the course of circulation is somewhat di?erent, owing to the fact that no nourishment comes from the bowels nor air into the lungs. Accordingly, two large arteries pass out of the navel, and convey blood to be changed by contact with maternal blood (see PLACENTA), while a large vein brings this blood back again. There are also communications between the right and left atria, and between pulmonary artery and aorta. The latter is known as the ductus arteriosus. At birth all these extra vessels and connections close and rapidly shrivel up.... circulatory system of the blood
A test for colour vision, introduced by a Japanese doctor, comprising several plates with round dots of di?erent colours and sizes. It is also the name of a type of blood test for SYPHILIS.... ishihara’s test
See under TESTICLE, DISEASES OF.... maldescended testis
The determination of eligibility for a publicly financed programme on the basis of an applicant’s income and assets (means).... means test
This body manages regional TRANSFUSION centres. Among its aims are the maintenance and promotion of blood and blood products based on a system of voluntary donors; implementing a cost-e?ective national strategy for ensuring adequate supplies of blood and its products to meet national needs; and ensuring high standards of safety and quality.... national blood authority
A test for MONONUCLEOSIS which is based upon the fact that patients with this disease develop ANTIBODIES which agglutinate sheep red blood cells.... paul-bunnell test
These have almost completely replaced BONE MARROW TRANSPLANT, used to treat malignancies such as LEUKAEMIA and LYMPHOMA for the past 20 years. The high doses of CHEMOTHERAPY or RADIOTHERAPY used to treat these diseases destroy the bone marrow which contains stem cells from which all the blood cells derive. In 1989 stem cells were found in the blood during recovery from chemotherapy. By giving growth factors (cytokines), the number of stem cells in the blood increased for about three to four days. In a peripheral-blood stem-cell transplant, these cells can be separated from the peripheral blood, without a general anaesthetic. The cells taken by either method are then frozen and returned intravenously after the chemotherapy or radiotherapy is completed. Once transplanted, the stem cells usually take less than three weeks to repopulate the blood, compared to a month or more for a bone marrow transplant. This means that there is less risk of infection or bleeding during the recovery from the transplant. The whole procedure has a mortality risk of less than 5 per cent – half the risk of a bone marrow transplant.... peripheral-blood stem-cell transplants
A test for INFERTILITY. A specimen of cervical mucus, taken up to 24 hours after coitus (during the post-ovulatory phase of the menstrual cycle), is examined microscopically to assess the motility of the sperms. If motility is above a certain level, then sperms and mucus are not interacting abnormally – thus eliminating one cause of sterility.... post-coital test
A hearing test in which a vibrating tuning fork is placed on the mastoid process (see EAR). When the subject can no longer hear the ringing, it is placed beside the ear. Normal subjects can then hear the noise once more, but in people with conductive DEAFNESS, air conduction does not persist after bone conduction has ceased. It can help to distinguish between nerve (sensorineural) and conduction deafness.... rinnes test
A tube of thin glass closed at one end, which is used for observing chemical reactions or for bacterial culture.... test-tube
A mathematical formula (or function) that is used to determine if the difference between outcomes of a treatment or intervention and a control group is great enough to conclude that the difference is statistically significant. Statistical tests generate a value that is associated with a particular P value. Among the variety of common statistical tests are: F, t, Z, and chi-square. The choice of a test depends upon the conditions of the study, e.g. what type of outcome variable is used, whether or not the subjects are randomly selected from a larger population, and whether it can be assumed that the outcome values of the population have a normal distribution or other type of distribution.... statistical test
A positive tourniquet test with scattered fine petechiae is one of the earliest clinical signs in dengue haemorrhagic fever.... tourniquet test
See under TESTICLE, DISEASES OF.... undescended testis
Venereal Diseases Research Laboratory Test. One of the non-treponemal reaginic tests for syphilis.... vdrl test
As a natural beverage, a cup of tea brings you many health benefits. One of them is related to blood pressure. Based on the type of tea you drink, it can help lower your blood pressure. Find out more about teas for blood pressure!
Problems with blood pressure
Blood pressure represents the pressure made by the circulating blood on the walls of the blood vessels. However, problems appear in the case of hypertension and hypotension.
Hypertension is a medical condition caused by a high blood pressure, while hypotension is caused by a low blood pressure. Both can be treated with one of the various types of tea for blood pressure.
Tea for high blood pressure
If you’ve got problems with hypertension (high blood pressure), hibiscus tea can help, as it is known to lower blood pressure. You can also pick one of these herbal teas: chrysanthemum tea, flax tea, periwinkle tea, red root tea, self-heal tea, white peony root tea, valerian tea, or wild cherry bark tea.
You can also drink hyssop tea, barberry tea, and rosemary tea, regardless of the blood pressure problem. These three teas will help regulate your blood pressure and reduce the risk of getting either high or low blood pressure problems.
Tea for low blood pressure
In the case of hypotension (low blood pressure), some of the teas you can try include lovage tea, ephedra tea, wu yi tea, cat’s claw tea, vervain tea, or wheatgrass tea. Black tea can help too, though you have to be careful with it as it has a high content of caffeine.
Forbidden teas for blood pressure problems
There are several teas which you should avoid drinking, no matter if you’ve got problems with high blood pressure or low blood pressure. The list of teas you shouldn’t drink includes arnica tea, black cohosh tea, gentian tea, juniper tea, lobelia tea, red ginseng tea, sage tea, stone root tea, and yohimbe tea.
Also, generally it isn’t recommended to drink tea that lowers blood pressure if you’ve got hypotension, or tea that leads to high blood pressure if you’ve got hypertension.
Whether you’ve got problems with high blood pressure or low blood pressure, try a more natural treatment: choose one of the many teas for blood pressure!... tea for blood pressure
A test with a tuning fork that is used to assess a person’s DEAFNESS.... weber’s test
An agglutination test used in the laboratory to diagnose rickettsial diseases. It depends on a nonspecific cross reaction between antibodies produced by the rickettsial infection with the OX-2, OX-19 and OXK antigens of the Gram negative rod, Proteus.... weil-felix test
A serological test used to detect antibodies in the diagnosis of typhoid. Antigens detected are the O (somatic), H (flagellar) and Vi (virulence) antigens.... widal test
See: BLEEDING (haemoptysis). ... coughing of blood
Popular blood tonic of the 1930s, 1940s and 1950s. Ingredients: Liquid Extract Liquorice 5 per cent, Infusion Gentian Co Conc 10 per cent, Infusion Senna Conc 5 per cent. And 25 per cent alcoholic extractive from Burdock 5 per cent, Red Clover 5 per cent, Queen’s root 2.5 per cent, Yellow Dock root 1.25 per cent, Poke root 2.5 per cent, Sarsaparilla 2.5 per cent. (Carter Bros) ... glentona herbal blood purifier
The SCROTUM may be affected by various skin diseases, particularly eczema (see DERMATITIS) or fungal infection. A HERNIA may pass into the scrotum. Defective development of the testicles may lead to their retention within the abdomen, a condition called undescended testicle.
Hydrocoele is a collection of ?uid distending one or both sides of the scrotum with ?uid. Treatment is by withdrawal of the ?uid using a sterile syringe and aspiration needle.
Hypogonadism Reduced activity of the testes or ovaries (male and female gonads). The result is impaired development of the secondary sexual characteristics (growth of the genitals, breast and adult hair distribution). The cause may be hereditary or the result of a disorder of the PITUITARY GLAND which produces GONADOTROPHINS that stimulate development of the testes and ovaries.
Varicocoele is distension of the veins of the spermatic cord, especially on the left side, the causes being similar to varicose veins elsewhere (see VEINS, DISEASES OF). The chief symptom is a painful dragging sensation in the testicle, especially after exertion. Wearing a support provides relief; rarely, an operation may be advisable. Low sperm-count may accompany a varicocele, in which case surgical removal may be advisable.
Orchitis or acute in?ammation may arise from CYSTITIS, stone in the bladder, and in?ammation in the urinary organs, especially GONORRHOEA. It may also follow MUMPS. Intense pain, swelling and redness occur; treatment consists of rest, support of the scrotum, analgesics as appropriate, and the administration of antibiotics if a de?nitive microorganism can be identi?ed. In some patients the condition may develop and form an ABSCESS.
Torsion or twisting of the spermatic cord is relatively common in adolescents. About half the cases occur in the early hours of the morning during sleep. Typically felt as pain of varying severity in the lower abdomen or scrotum, the testis becomes hard and swollen. Treatment consists of immediate undoing of the torsion by manipulation. If done within a few hours, no harm should ensue; however, this should be followed within six hours by surgical operation to ensure that the torsion has been relieved and to ?x the testes. Late surgical attention may result in ATROPHY of the testis.
Tuberculosis may occur in the testicle, especially when the bladder is already affected. Causing little pain, the infection is often far advanced before attracting attention. The condition generally responds well to treatment with a combination of antituberculous drugs (see also main entry for TUBERCULOSIS).
Tumours of the testes occur in around 600 males annually in the United Kingdom, and are the second most common form of malignant growth in young males. There are two types: SEMINOMA and TERATOMA. When adequately treated the survival rate for the former is 95 per cent, while that for the latter is 50 per cent.
Injuries A severe blow may lead to SHOCK and symptoms of collapse, usually relieved by rest in bed; however, a HAEMATOMA may develop.... testicle, diseases of
The first intelligence test that attempted to measure higher mental functions, devised in 1905.... binet test
Tests to screen for and diagnose bleeding disorders, usually resulting from deficiencies or abnormalities of blood coagulation factors or of platelets (see blood clotting). Tests are also used to monitor treatment with anticoagulant drugs.... blood-clotting tests
See culture.... blood culture
The level of glucose in the blood. Abnormally high blood glucose (sometimes called sugar) levels are an indication of diabetes mellitus. (See also hyperglycaemia; hypoglycaemia.)... blood glucose
See blood film.... blood smear
The use of a person’s own blood, donated earlier, for blood transfusion. Autologous transfusion eliminates the slight but serious risk of contracting a serious infectious illness from contaminated blood. There is no risk of a transfusion reaction occurring as a result of incompatibility between donor and recipient blood. Up to 3.5 litres of blood can be removed and stored in several sessions at least 4 days apart and up to 3 days before planned surgery. Blood may be salvaged during surgery, filtered and returned to the circulation, reducing the need for transfusion of donated blood.... blood transfusion, autologous
Cells, also called blood corpuscles, present in blood for most or part of their lifespan. They include red blood cells, which make up about 45 per cent by volume of normal blood, white blood cells, and platelets. Blood cells are made in the bone marrow by a series of divisions from stem cells.
Red blood cells (also known as RBCs, red blood corpuscles, or erythrocytes) transport oxygen from the lungs to the tissues (see respiration). Each is packed with haemoglobin, enzymes, minerals, and sugars. Abnormalities can occur in the rate at which RBCs are either produced or destroyed, in their numbers, and in their shape, size, and haemoglobin content, causing forms of
anaemia and polycythaemia (see blood, disorders of).
White blood cells (also called WBCs, white blood corpuscles, or leukocytes) protect the body against infection and fight infection when it occurs. The 3 main types of are granulocytes (also called polymorphonuclear leukocytes), monocytes, and lymphocytes. Granulocytes are further classified as neutrophils, eosinophils, or basophils, and each type of granulocyte has a role in either fighting infection or in inflammatory or allergic reactions. Monocytes and lymphocytes also play an important part in the immune system. Lymphocytes are usually formed in the lymph nodes. One type, a T-lymphocyte, is responsible for the delayed hypersensitivity reactions
White (see allergy) and Red blood blood cell is also involved in cell (neutrophil) protection against cancer. T-lymphocytes manufacture chemicals, known as lymphokines, which affect the function of other cells. In addition, the T-cells moderate the activity of B-lymphocytes, which form the antibodies that can prevent a second attack of certain infectious diseases. Platelets (also known as thrombocytes), are the smallest blood cells and are important in blood clotting.
The numbers, shapes, and appearance of the various types of blood cell are of great value in the diagnosis of disease (see blood count; blood film).... blood cells
Disorders resulting from abnormalities in any of the components of blood or from infection. Disorders include types of anaemia, polycythaemia, bleeding disorders, and unwanted clot formation (thrombosis), hypoalbuminaemia (albumin deficiency) and agammaglobulinaemia (deficiency of gamma-globulin). Blood disorders such as sickle cell anaemia, thalassaemia, and haemophilia are inherited. Bone marrow cancers that affect production of blood components include leukaemia, polycythaemia vera, and multiple myeloma. Blood poisoning is usually due to septicaemia or a toxin such as carbon monoxide. Some drugs can cause blood abnormalities as a side effect. (See also anaemia, haemolytic; anaemia, iron-deficiency; anaemia, megaloblastic; malaria; hyperbilirubinaemia.)... blood, disorders of
A general term given to arteries, veins, and capillaries (see circulatory system).... blood vessels
One of a group of tests used to assess the function of the heart in people who experience chest pain, breathlessness, or palpitations during exercise. The test establishes whether the patient has coronary artery disease. An ECG machine records the patterns of the heart’s electrical activity while the heart is stressed. This is usually achieved by the patient exercising on a treadmill or cycling. Specific changes in the electrical pattern as exercise levels increase indicate angina. Cardiac stress testing may be used in conjunction with radionuclide scanning to identify damaged areas of heart muscle.... cardiac stress test
Analysis of a sample of blood to give information on its cells and proteins and any of the chemicals, antigens, antibodies, and gases that it carries. Such tests can be used to check on the health of major organs, as well as on respiratory function, hormonal balance, the immune system, and metabolism. Blood tests may look at numbers, shape, size, and appearance of blood cells and assess the function of clotting factors. The most important tests are blood count and blood group tests if transfusion is needed. Biochemical tests measure chemicals in the blood (see acid–base balance; kidney function tests; liver function tests). Microbiological tests (see immunoassay) look for microorganisms that are in the blood, as
in septicaemia. Microbiology also looks for antibodies in the blood, which may confirm immunity to an infection. blood transfusion The infusion of large volumes of blood or blood products directly into the bloodstream to remedy severe blood loss or to correct chronic anaemia. In an exchange transfusion, nearly all of the recipient’s blood is replaced by donor blood. Before a transfusion, a sample of the recipient’s blood is taken to identify the blood groups, and it is matched with suitable donor blood. The donor blood is transfused into an arm vein through a plastic cannula. Usually, each unit (about 500 ml) of blood is given over 1–4 hours; in an emergency, 500 ml may be given in a couple of minutes. The blood pressure, temperature, and pulse are monitored during the procedure.
If mismatched blood is accidentally introduced into the circulation, antibodies in the recipient’s blood may cause donor cells to burst, leading to shock or kidney failure. Less severe reactions can produce fever, chills, or a rash. Reactions can also occur as a result of an allergy to transfused blood components. All
blood used for transfusion is carefully screened for a number of infectious agents, including HIV (the AIDS virus) and hepatitis B and hepatitis C.
In elderly or severely anaemic patients, transfusion can overload the circulation, leading to heart failure.
In patients with chronic anaemia who need regular transfusion over many years, excess iron may accumulate (haemosiderosis) and damage organs such as the heart, liver, and pancreas.
Treatment with desferrioxamine to remove excess iron may be needed.... blood tests
The main mechanism by which blood clots are formed, involving a complex series of reactions in the blood plasma (see blood clotting).... coagulation, blood
See faeces, abnormal; rectal bleeding.... faeces, blood in the
A test for meningitis that involves pressing a clear glass against a rash. If the rash remains visible, it may be a form of purpura, which sometimes occurs in meningitis.... glass test
An outdated psychological test in which the subject was asked to interpret the appearance of a number of ink blots. The most widely used example was the Rorschach test.... ink-blot test
See pulmonary function tests.... lung function tests
The presence in the faeces of blood that cannot be seen by the naked eye, but can be detected by chemical tests. Such tests are widely used in screening for cancer of the colon (see colon, cancer of). Faecal occult blood may also be a sign of a gastrointestinal disorder such as oesophagitis, gastritis, or stomach cancer; cancer of the intestine (see intestine, cancer of); rectal cancer (see rectum, cancer of); diverticular disease; polyps in the colon; ulcerative colitis; or irritation of the stomach or intestine by drugs such as aspirin. (See also rectal bleeding.)... occult blood, faecal
Questionnaires designed to define various personality traits or types. Tests may be designed to detect psychiatric symptoms, underlying personality traits, how outgoing or reserved a person is, and predisposition to developing neurotic illness.... personality tests
See Guthrie test.... pku test
See pulmonary function tests.... respiratory function tests
A type of intelligence test.... stanford–binet test
A rare, cancerous tumour of the testis. Testicular cancer is most common in young to middle-aged men, and the risk increases in individuals with a history of undescended testis (see testis, undescended). The most common types of testicular cancer are seminomas, which are made up of only 1 type of cell, and teratomas. The cancer usually appears as a firm, painless swelling of 1 testis. There may also be pain and inflammation. Biopsy, followed by orchidectomy, is the usual treatment, and may be combined with chemotherapy. The tumours usually respond well to treatment.... testis, cancer of
A testis that is absent from the scrotum because it has descended into an abnormal position, usually in the groin or at the base of the penis. The condition is most often discovered soon after birth during a routine physical examination. It is treated by orchidopexy. (See also testis, undescended.) ... testis, ectopic
Pain in a testis may be caused by mild injury, a tear in the wall of the testis due to a direct blow, orchitis, epididymo-orchitis, and torsion of the testis (see testis, torsion of). Sometimes, no cause is found and the pain disappears without treatment. If the wall of the testis is torn, an operation to repair it may be needed. ... testis, pain in the
Swelling of the testis or the surrounding tissues in the scrotum. Harmless and painless swellings include epididymal cysts, hydroceles, varicoceles, and spermatoceles. Cancer of the testis (see testis, cancer of) is rare but may be a cause of painless swelling. Swelling that is painful may be caused by a direct blow, torsion of the testis (see testis, torsion of), orchitis, epididymoorchitis, or, in very rare cases, cancer of the testis. Any swelling of the testes should be assessed promptly by a doctor.... testis, swollen
A group of blood tests used to evaluate the function of the thyroid gland and to detect or confirm any thyroid disorder. The thyroid hormones T3 and T4 are measured, as well as thyroid-stimulating hormone (TSH), the pituitary gland hormone that stimulates the thyroid gland.... thyroid-function tests
Skin tests used to determine whether or not a person has been exposed to the bacterium that causes tuberculosis. Tuberculin tests are carried out for diagnosis of tuberculosis, and before BCG vaccination. A small amount of tuberculin (purified protein from the bacteria) is injected into the skin. A few days later, the skin reaction, if any, is noted. A reaction indicates previous exposure.... tuberculin tests
Hearing tests carried out to diagnose conductive deafness. In the Weber test, a vibrating tuning fork is held against the forehead. If there is conductive hearing loss, the sound seems louder in the affected ear. In the Rinne test, a vibrating tuning fork is held first near the ear, and then against the bone behind it. If it sounds louder when held against the bone, there is conductive hearing loss.... tuning fork tests
See urinalysis.... urine tests
a test for the presence of sugar in urine or other liquids. A few drops of the test solution are added to Benedict’s solution, prepared from sodium or potassium citrate, sodium carbonate, and copper sulphate. The mixture is boiled and shaken for about two minutes, then left to cool. The presence of up to 2% glucose is indicated by the formation of a reddish, yellowish, or greenish precipitate, the highest levels corresponding to the red coloration, the lowest (about 0.05%) to the green. [S. R. Benedict (1884–1936), US surgeon]... benedict’s test
(blood corpuscle) any of the cells that are present in the blood in health or disease. The cells may be subclassified into three major categories, namely red cells (*erythrocytes); white cells (*leucocytes), which include granulocytes, lymphocytes, and monocytes; and *platelets (see illustration). The blood cells account for approximately 40% of the total volume of the blood in health; red cells comprise the vast majority.... blood cell
(blood clotting) the process whereby blood is converted from a liquid to a solid state. The process may be initiated by contact of blood with a foreign surface (intrinsic system) or with damaged tissue (extrinsic system). These systems involve the interaction of a variety of substances (*coagulation factors) and lead to the production of the enzyme thrombin, which converts the soluble blood protein *fibrinogen to the insoluble protein *fibrin, forming the blood clot. Finally, fibrin is broken down by the action of *plasmin. Anticoagulants and tissue plasminogen activators act by inhibiting or activating various pathways in this cascade (see illustration). Blood coagulation is an essential mechanism for the arrest of bleeding (*haemostasis). See also platelet activation.... blood coagulation
Blood group of people donor can receive blood from... donor’s blood group
... blood plasma see plasma.
see serum.... blood serum
(in statistics) a test to determine if the difference between two groups of observations is statistically significant (see significance), used in controlled trials and other studies. It measures the differences between theoretical and observed values and identifies whether or not *variables are related.... chi-square test
a test used to detect a squint. The observer looks at a target object, one eye at a time being covered. If the uncovered eye deviates to focus on the target, then a squint is confirmed. The movement can be up, down, sideways, or a combination, depending on the type of squint (see strabismus).... cover test
a screening tool for young people under the age of 21 to identify alcohol and drug use. The first part consists of three questions about drug or alcohol use over the past year. Participants giving positive answers to two or more questions proceed to the second part (from which the name derives), which contains six questions with the key words car, relax, alone, family/friends, forget, trouble, used to assess the need for further input.... crafft screening test
where clinical *negligence is claimed, tests used to determine the standard of care owed by professionals to those whom they serve, e.g. the standards of care provided to patients by doctors. The 1957 case of Bolam v Friern Hospital Management Committee established that if a doctor acts in accordance with a responsible body of medical opinion, he or she will not be negligent. In 1997 this standard of care test was amended by the case of Bolitho v City and Hackney Health Authority, which requires the doctor’s behaviour to satisfy the judgment not only of responsible medical opinion but also of a court’s own independent logical analysis.... bolam and bolitho tests
(DSTs) tests based on the principle that appropriate doses of *dexamethasone can suppress the output of cortisol from the adrenal glands in the normal state and that this ability is reduced or lost in *Cushing’s syndrome. In the overnight DST 1 mg of dexamethasone is administered at midnight and the serum cortisol level is measured at 9.00 am the next morning. Failure to suppress cortisol output may indicate Cushing’s syndrome but also occurs in patients with obesity and depressive illness. In the low-dose DST (0.5 mg dexamethasone every 6 hours for 48 hours), cortisol suppression occurs in patients with obesity and depression but not in those with Cushing’s syndrome. In the high-dose DST (2 mg dexamethasone every 6 hours for 48 hours), cortisol is suppressed in patients with Cushing’s disease (in which excess amounts of ACTH are secreted by the pituitary gland) but not in those with Cushing’s syndrome due to other causes. Although the low- and high-dose tests are unreliable, all three tests should be performed to aid the diagnosis of Cushing’s syndrome.... dexamethasone suppression tests
a hearing test used for screening infants between the ages of six and ten months. The infant is placed on its carer’s knee, one examiner sits in front of the infant and gains its attention, and a second examiner is situated just behind the infant. At a given moment the first examiner becomes very still and the second examiner makes a sound at the level of the infant’s ear to one side or the other. If the infant can hear it turns in the direction of the sound. The sounds made should be of different pitches and a given loudness.... distraction test
(Hallpike test) a test for *benign paroxysmal positional vertigo (BPPV), performed with the patient first sitting upright on an examination couch and then lying supine with the head and neck extended beyond the edge of the couch. The patient’s head is rotated to the left (or right) and supported by the examiner while the patient assumes the supine position and keeps his or her eyes focused on the examiner’s eyes. The test is then repeated with the other ear facing down. In patients with BPPV, after a short delay rotatory *nystagmus is seen, in association with severe vertigo and nausea, which gradually abates. The effect diminishes with repeated manoeuvres. In conditions affecting the cerebellum or brainstem, the nystagmus occurs immediately, in any direction, and does not diminish, and patients do not feel especially nauseated. [M. R. Dix and C. S. Hallpike (20th century), British otologists]... dix–hallpike test
see calprotectin.... faecal calprotectin
see incontinence.... faecal incontinence
see elastase.... faecal pancreatic elastase
a test for detecting the presence of sugar in urine, which has now been replaced by better and easier methods. [H. von Fehling (1812–85), German chemist]... fehling’s test
a test for folate or vitamin B12 deficiency. A dose of the amino acid histidine, which requires the presence of folate or vitamin B12 for its complete breakdown, is given by mouth. In the absence of these vitamins, formiminoglutamic acid (figlu) – an intermediate product in histidine metabolism – accumulates and can be detected in the urine.... figlu test
a test for *ataxia or cerebral lesions. Using the index finger, the patient alternately touches his or her nose and then the examiner’s finger, which is shifted to a new position for each of the patient’s movements. The test is positive if the patient misses a target or develops a tremor as the target is approached (intention tremor).... finger–nose test
(FPL test) a test used to evaluate the *visual acuity of infants and young children by observing whether the child looks at a blank screen or one with stripes, the spatial frequency of which can be changed.... forced preferential looking test
see forced preferential looking test.... fpl test
a rarely used diagnostic test for the sexually transmitted disease *lymphogranuloma venereum. A small quantity of the virus, inactivated by heat, is injected into the patient’s skin. If the disease is present a small red swelling appears at the site of injection within 48 hours. [W. S. Frei (1885–1943), German dermatologist]... frei test
a test for *phaeochromocytomas not displaying typically high levels of plasma *catecholamines. An intravenous bolus of *glucagon is administered and the test is positive when there is a threefold increase in plasma catecholamine levels with a consequent rise in blood pressure. The test is now very rarely used due to safer and more sensitive screening tests, combined with modern tumour imaging techniques.... glucagon stimulation test
(heel-prick blood test) a blood test performed on all newborn babies at the end of the first week of life. The blood is obtained by pricking the heel of the baby. The test can detect several *inborn errors of metabolism (including *phenylketonuria) and *hypothyroidism; it can also be used for detecting *cystic fibrosis, although this is not routinely offered. [R. Guthrie (1916–95), US paediatrician]... guthrie test
see Dix–Hallpike test.... hallpike test
see Guthrie test.... heel-prick blood test
a test for the presence of protein (albumin) in the urine. A quantity of urine is carefully poured onto the same quantity of pure nitric acid in a test tube. A white ring forms at the junction of the liquids if albumin is present. However, a similar result may be obtained if the urine contains certain drugs or is very concentrated. A dark brown ring indicates the presence of an abnormally high level of potassium indoxyl sulphate in the urine (see indicanuria). [J. F. Heller (1813–71), Austrian pathologist]... heller’s test
an important but potentially dangerous test of anterior pituitary function involving the deliberate induction of a hypoglycaemic episode with injected insulin and the subsequent measurement of plasma cortisol and growth hormone at regular intervals over the next three hours. The stress of the hypoglycaemia should induce a rise in the levels of these hormones unless the anterior pituitary or the adrenal glands are diseased. The test can induce epileptic seizures or angina in those with a predisposition and should not be performed in susceptible individuals. It is often combined with the thyrotrophin-releasing hormone (TRH) test and the gonadotrophin-releasing hormone (GnRH) test in what is known as the triple test (or dynamic pituitary function test).... insulin stress test
a card with text printed in type of different sizes, used for testing acuity of near vision. [E. R. Jaeger von Jastthal (1818–84), Austrian ophthalmologist]... jaeger test types
a test to detect and measure fetal red blood cells in the maternal circulation of Rh-negative women who have *antepartum haemorrhage or have previously had a Rh-positive baby. It is used to calculate the correct dose of *anti-D immunoglobulin that will prevent *haemolytic disease of the newborn.... kleihauer–betke test
a test of the ability of the pituitary to secrete growth hormone, in which levodopa is administered by mouth and plasma levels of growth hormone are subsequently measured (they should peak within the following hour). It is a safer alternative to the *insulin stress test but does not give information on cortisol production, which is usually more clinically important to know.... levodopa test
see significance.... mann–whitney u test
a hearing test used in preschool children in which the child must discriminate between similar speech sounds. The test consists of 14 toys that are paired because their names sound similar; for example, tree and key, plane and plate. Having first identified all the objects, the child is then asked in a quiet voice to indicate a particular toy (e.g. Can you find the key?).... mccormick toy test
a simple noninvasive procedure that enables the detection of *carriers for single gene defects, e.g. *cystic fibrosis. Epithelial cells from the buccal cavity are obtained from a saline mouthwash: from these it is possible to isolate DNA, which is amplified by the *polymerase chain reaction to enable gene analysis.... mouthwash test
a three-question tool designed to uncover any connection between an individual’s attendance at an A & E department and alcohol-related problems, thereby creating the potential for intervention and referral.... paddington alcohol test
see significance.... parametric test
a test used in the investigation of infertility. A specimen of cervical mucus, taken 6–24 hours after coitus, is examined under a microscope. The appearance of 10 or more progressively motile spermatozoa per high-power field in the specimen indicates that there is no abnormal reaction between spermatozoa and mucus. The test should be undertaken in the postovulatory phase of the menstrual cycle.... postcoital test
(in psychology) a way of measuring aspects of personality, in which the subject is asked to talk freely about ambiguous objects. His responses are then analysed. Examples are the *Rorschach test and the Thematic Apperception Test (in which the subject invents stories about a set of pictures).... projective test
any of several methods used to demonstrate whether or not a woman is pregnant. Most pregnancy tests are based on the detection of a hormone, *human chorionic gonadotrophin (hCG), in the urine. The sample of urine is mixed with serum containing antibodies to hCG and marker particles (sheep red cells or latex particles) coated with hCG. In the absence of pregnancy, the antibodies will cause *agglutination of the marker particles. If the urine is from a pregnant woman, the antibodies will be absorbed and no agglutination will occur. These tests may be positive for pregnancy as early as 30 days after the date of the last normal period and are 98% accurate. Newer tests using *monoclonal antibodies (beta hCG) are more easily interpreted. When carried out on serum rather than urine, these tests give even earlier positive results.... pregnancy test
a part of the routine *lumbar puncture procedure. It is used to determine whether or not the flow of cerebrospinal fluid is blocked in the spinal canal. [H. H. G. Queckenstedt (1876–1918), German physician]... queckenstedt test
tests for assessing the function of the kidneys. These include measurements of the specific gravity of urine, creatinine *clearance time, and blood urea levels; intravenous urography; and renal angiography.... renal function tests
a test to determine whether *deafness is conductive or sensorineural. A vibrating tuning fork is held first in the air, close to the ear, and then with its base placed on the bone (mastoid process) behind the ear. If the sound conducted by air is heard louder than the sound conducted by bone the test is positive and the deafness sensorineural; a negative result, when the sound conducted by bone is heard louder, indicates conductive deafness. [H. A. Rinne (1819–68), German otologist]... rinne’s test
a method of testing urine for the presence of acetone or acetoacetic acid: a sign of *diabetes mellitus. Strong ammonia is added to a sample of urine saturated with ammonium sulphate crystals and containing a small quantity of sodium nitroprusside. A purple colour confirms the presence of acetone or acetoacetic acid. [A. C. H. Rothera (1880–1915), Australian biochemist]... rothera’s test
a test to determine whether a person is susceptible to diphtheria. A small quantity of diphtheria toxin is injected under the skin; a patch of reddening and swelling shows that the person has no immunity and – if at particular risk – should be immunized. With safer *toxoids, this test is no longer necessary. [B. Schick (1877–1967), US paediatrician]... schick test
a test used to assess a patient’s capacity to absorb vitamin B12 from the bowel. Radioactive vitamin B12 is given by mouth and urine collected for 24 hours. A normal individual will excrete at least 10% of the original dose over this period; a patient with *pernicious anaemia will excrete less than 5%. [R. F. Schilling (1919), US physician]... schilling test
a test for detecting visual impairment in children who are too young to be able to read the *Snellen chart. A series of cards, each marked with a single letter of a specific size, are held up at a distance of 6 metres from the child being tested. The child is provided with an identification card containing a selection of letters and is asked to point to the letter that is the same as the one on the card in the distance. The test is suitable for children between the ages of two and seven.... sheridan–gardiner test
an investigation to seek evidence of cardiac *ischaemia. The heart is stressed by exercise or by the administration of an intravenous drug that increases heart rate (i.e. mimicked exercise). Ischaemia may then be detected by electrocardiography (stress ECG or exercise ECG), *echocardiography (showing the development of impaired function in areas of heart muscle that are ischaemic), *myocardial perfusion scan, or cardiac MRI.... stress test
see significance. [Pseudonym of W. S. Gosset (1876–1937), British statistician]... student’s t test
Standard Tests for Young Children and Retardates: tests to detect visual problems in children between the ages of six months and five years. They consist of a series of standardized balls, toys, or letters. The tests were developed by the paediatrician Mary Sheridan.... stycar tests
tests used to assess the ability of the adrenal cortex to produce cortisol. Serum cortisol is measured before and then 30 minutes (or 5 hours) after an intramuscular injection of 250 ?g (or 1 mg) tetracosactide (Synacthen), an analogue of *ACTH. The adrenal glands are considered to be inadequate if there is a low baseline concentration of cortisol or the rise is less than a certain predefined amount.... synacthen tests
(Trendelenburg’s sign) a test for detecting dysfunction of the hip joint. Normally when a leg is lifted off the ground, the pelvis on the same side is raised by the hip abductor muscles on the other side. If these muscles cannot raise the pelvis against body weight, the pelvis will tilt downwards and the test is positive, indicating arthritis, paralysis of the muscles due to superior gluteal nerve injury, or other hip pathology (e.g. congenital hip dislocation). [F. Trendelenburg]... trendelenburg’s test
1. (in *prenatal screening) a blood test that can be performed between the 15th and 20th weeks of pregnancy but has largely been replaced by combined first-trimester *PAPP-A screening and *nuchal translucency scanning. Levels of *alpha-fetoprotein (AFP), *unconjugated oestriol (uE3), and *human chorionic gonadotrophin (hCG) in the serum are computed with maternal age to determine the statistical likelihood of the fetus being affected by Down’s syndrome or spina bifida. The double test is similar but omits measurement of uE3. 2. see insulin stress test.... triple test
haemopoietic *stem cells collected from umbilical cord blood donated at birth, which can be stored indefinitely and used if a sibling or any other blood-compatible baby develops an illness (such as leukaemia) that could only be treated by cord-blood stem-cell transplantation. This facility is now available in the UK and the USA.... umbilical cord blood banked stem cells
(VEMP) a test used to measure the response of the *saccule. It is used in the diagnosis of *superior canal dehiscence syndrome, *Ménière’s disease, and other disorders of the inner ear.... vestibular evoked myogenic potential test
a test for *diabetes insipidus in which fluid and food intake is withheld completely for up to 24 hours, with regular measurement of plasma and urinary *osmolality and body weight. Normally (and in a person with psychogenic *polydipsia) the output of *vasopressin will be increased in order to concentrate the urine as the plasma osmolality rises; correspondingly, the urine osmolality also rises and its volume diminishes. In a patient with diabetes insipidus, however, the urine osmolality will remain low and of high volume while the patient steadily dehydrates. The test must be abandoned if the patient loses 3% of body weight.... water-deprivation test
a hearing test in which a vibrating tuning fork is placed at the midpoint of the forehead. A normal individual hears it equally in both ears, but if one ear is affected by conductive *deafness the sound appears louder in the affected ear. If one ear has a sensorineural deafness the sound appears louder in the unaffected ear. [F. E. Weber (1832–91), German otologist]... weber’s test
a direct percutaneous renal infusion test to investigate possible obstruction of the ureter or kidney. It detects subtle obstructions that cannot be detected by imaging. [R. Whitaker (20th century), British urologist]... whitaker’s test
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