Specificity, medical tests

Evaluate specific medical testing to determine potential site exposures. 

Reassurance seeking is not unusual, either (Warwick and Salkovskis 1985). This may involve asking doctors to check that a disease has not been contracted, requesting specific medical tests, looking up information in books or on the Internet, or informing relatives about the symptoms experienced and... 

Commercial use of cell and tissue culture continues to expand. Improvement of organisms through recombinant nucleic acid techniques has become commonplace. Formerly, a few laboratories were well ahead of most others, but now the methods have been perfected for routine use. Another technique that is widely practiced is culturing of cells that excrete high concentrations of just one antibody protein. The specificity of antibodies and antigens is exploited in medical testing procedures using these pure monoclonal antibodies. 

Contractor records at Site H indicated that medical tests and procedures included annual examinations that addressed site-specific hazards and were provided with the frequency required by the standard. Records at Site K showed that employees of both contractors had received recent comprehensive medical examinations, and copies of the physician s written opinion were maintained for each employee. These... 

There are medical tests to determine whether you have been exposed to mirex. Levels of mirex can be measured in blood, feces, fat, or milk. The tests are not done in routine medical examinations. However, doctors can collect tissue and body fluid samples and send them to university medical centers or medical laboratories where the tests can be performed. The tests are specific for mirex exposure. Since mirex is stored in your body for a long time and slowly excreted, the tests can detect mirex for a long time after exposure has stopped. However, the tests are unsatisfactory indicators of the amount of mirex to which you have been exposed. This is because a long time may have passed since you were exposed and you cannot be sure how much mirex may have left your body by the time the test is performed. The tests also cannot be used to predict whether you will experience any potential health effects or harmful changes following exposure. 

Disulfoton and its breakdown products can be measured in the blood, urine, feces, liver, kidney, or body fat of exposed people. In cases of occupational or accidental exposure to disulfoton, the breakdown products are often measured in the urine. The breakdown products are relatively specific for disulfoton and a few other similar organophosphate pesticides and can be detected in urine for up to one week after people were last exposed. Because disulfoton inhibits cholinesterase in blood and in blood cells, inhibition of this enzyme activity may also suggest exposure to disulfoton. Cholinesterase activity in blood and in blood cells may remain inhibited for as long as 1-2 weeks after the last exposure. Because other organophosphate pesticides also inhibit cholinesterase activity in blood and blood cells, this test is not specific for disulfoton. The measurement of cholinesterase in blood and blood cells and the amount of disulfoton breakdown products in the urine cannot always predict how much disulfoton you were exposed to. Your doctor can send samples of your blood or urine to special laboratories that perform these tests. Chapters 2 and 6 provide more information about medical tests. 

A simple, fast and specific color test for urea nitrate was reported recently by Almog et al. It is based on the reaction between urea nitrate and ethanolic solution ofp-dimethylaminocinnamaldehyde (p-DMAC) (9) under neutral conditions [91]. A red pigment is formed within 1 min from contact. Its structure has also been determined by the same group, by X-ray crystallography [92]. It appears to be a resonance hybrid between a protonated Schiffbase (10) and a quinoid system (10a) (Eq. (14)). The limit of detection on filter paper is 0.1 mg/cm. Urea itself, which is the starting material for urea nitrate, does not react with p-DMAC under the same conditions. Other potential sources of false-positive response such as common fertilizers, medications containing the urea moiety and various amines, do not produce the red pigment with p-DMAC. 

There is no medical test that shows if you have been exposed to fuel oils. There are methods to determine if your blood contains some fuel oil components such as benzene, toluene, and xylenes however, the concentrations of these compoimds in distilled fuels are so low that if they were detected in your blood, it might not indicate specific or exclusive exposure to fuel oils. For information on tests for measuring exposure to some individual components of fuel oils, see the ATSDR toxicological profiles on benzene, toluene, total xylenes, and polycyclic aromatic hydrocarbons. See Chapters 2 and 6 for information on symptoms that suggest exposure to fuel oils. 

Because BCME is broken down so rapidly in the body, there are no specific tests to determine if a human has been exposed to this compound. The only available medical tests are physical examination of the nose and throat, chest X-ray, and examination of the sputum for abnormal cell types. Unfortunately, these tests are not specific for this compound, and would reveal effects of the compound only after damage to the tissues had already occurred. More information on ways to measure BCME is provided in Chapter 6. 

The work of the medicinal chemist is centred around the discovery of new lead compounds with specific medical properties. It includes the development of more effective and safer analogues from both these new and existing lead compounds. This usually involves synthesizing and testing many hundreds of compounds before a suitable compound is produced. It is currently estimated that for every 10000 compounds synthesized one is suitable for medical use. 

The most specific test that can be used to determine if you have been exposed to DEHP is the measurement of MEHP and other breakdown chemicals in your urine or blood. This test only provides a measure of recent exposure, since DEHP is rapidly broken down into other substances and excreted from your body. You also could be tested for another breakdown product (phthalic acid), but this test would not be specific for DEHP. One or 2 days after exposure, your feces could be tested for the presence of DEHP metabolites. These tests are not routinely available through health care providers. More information on medical tests for DEHP is found in Chapters 3 and 7. 

The health effects of the different barium compounds depend on how well the specific barium compound dissolves in water. For example, barium sulfate does not dissolve well in water and has few adverse health effects. Doctors sometimes give barium sulfate orally or by placing it directly in the rectum of patients for purposes of making x-rays of the stomach or intestines. The use of this particular barium compound in this type of medical test is not harmful to people. Barium compounds such as barium acetate, barium carbonate, barium chloride, barium hydroxide, barium nitrate, and barium sulfide that dissolve in water can cause adverse health effects. Most of what we know comes from studies in which a small number of individuals were exposed to fairly large amounts of barium for short periods. Eating or drinking very large amounts of barium compounds that dissolve in water may cause paralysis or death in a few... 

Tests for food allergy, like other medical tests, are neither 100% sensitive nor 100% specific. 

During World War I and World War II, most workers who routinely handled tetryl powder and pellets in munitions factories developed a distinct yellow staining of the skin. Many workers also developed skin rashes. These workers were exposed to high concentrations of tetryl dust in the air and by direct contact with the explosives. There are no medical tests to show if you have been specifically exposed to tetryl. However, if the breakdown products of tetryl found in the urine of animals exposed to tetryl were also present in the urine of exposed humans, these breakdown products could be used to indicate exposure to tetryl or similar substances. The symptoms caused by exposure to tetryl can also occur for many other reasons therefore, they cannot be used as proof of tetryl exposure. Refer to Chapters 2 and 6 for more information. 

Lumbar puncture (also called LP)—medical test in which a very narrow needle is inserted into a specific space between the vertebrae of the lower back in order to draw off and examine a sample of CSF. 

Symptoms can occur within hours of drug administration or after more than 15 years of using a drug. Most classes of medications have been reported to cause vascuhtis. There are no specific diagnostic tests for drug-induced vascuhtis. Antineutrophil cytoplasmic autoantihodies have been identified in many cases of drug-induced vasculitis. Eosinophiha, leukocytosis, and elevated ESR also may occur. 

Specific laboratory tests to investigate the possible presence of von Willebrand disease include measurement of von Willebrand factor antigen (vWF Ag) level, factor VIII assay, determination of ristocetin cofactor activity, and von Willebrand factor multimer analysis. Plasma concentrations of von Willebrand factor increase with cigarette smoking, exercise, pregnancy, and infection, as well as with the use of certain medications, such as corticosteroids, birth control pills, and desmopressin. Repeated test measurements may be... 

In addition to the specific comments, the panelists discussed the availability and implications of medical tests to characterize PCB levels in blood, body fat, and breast milk. Though the profile clearly states that routine clinical tests are not available, some panelists suggested that ATSDR include more detailed information on this topic, such as whether tests will be commercially available, how people can get tested by physicians and specialists, and how medical professionals should interpret the significance of measured PCB levels. During this discussion, several panelists indicated that the profile does not acknowledge that no treatments are currently available to reduce body burdens of PCBs. One panelist noted that PCB tests are currently available to physicians, but some testing methods have relatively high detection limits and inadequate quality assurance measures. 

Accounting for its purpose, every significance test has to be designed individually A medical test should always warn the patient in case of a severe disease on the other hand, establishing a result by means of statistics, a test should preferably reject false positive results. These antithetic demands are represented by the terms of sensitivity and specificity ... 

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