In-home tests make health care easier.
Another device, the home meter for testing blood glucose (sugar) levels con -- within seconds -- electronically analyze a blood drop from a finger prick, so a person with diabetes knows whether to adjust medicine, exercise or diet.
"By creating the potential for tight control of diabetes, the blood glucose meter has revolutionized this area of medical practice," says the Food and Drug Administration's Steven Gutman, M.D. "It's a cornerstone of modern diabetic therapy."
Generally, in-home tests provide easy access to medical knowledge about one's health. In some cases, such as monitoring high blood _pressure, home testing reduces the number of times a patient must visit a doctor's office or laboratory, thereby reducing medical costs. People also may feel an increased sense of control over their health.
An over-the-counter (OTC) test performs at least one of three functions:
* doctor-recommended monitoring (e.g., blood pressure, for hypertension; blood glucose, for diabetes control; ovulation, for infertility)
* detecting markers for possible health conditions when there are no physical signs or symptoms (blood cholesterol level, for high cholesterol; hidden [occult] blood in stool, for colon or rectal cancer)
* detecting markers for specific conditions when there are physical signs or symptoms (a specific female hormone in urine after a missed period, for pregnancy).
* Not all tests on the OTC market are equally useful, however, says Philip Phillips, deputy director of the F.D.A.s Office of Device Evaluation.
* "Some OTC tests that have been marketed for many years," he says, "may not be as useful or acceptable as some consumers believe."
Eye charts, Phillips notes for example, have been sold for decades and are still around in some drugstores, "but you shouldn't rely on them if you think you need eyeglasses or have not had a recent examination." People having eye problems should be examined by a licensed eye-care professional, he says.
The more recently approved in-home tests are as reliable as professional tests. Still, all tests can generate false positives (indicating someone has a condition when in fact the person does not) or false negatives (a result that does not identify a condition that is in fact present) -- particularly if the user doesn't follow directions.
Instead of signifying colon or rectal cancer, a positive result on a test for hidden blood in stool could reflect such factors as bleeding gums or last night's T-bone steak. Or an untrained person may perform the test incorrectly, causing hidden blood in the stool to go undetected.
A false negative can occur with a pregnancy test. When a urine sample has a certain level of human chorionic gonadotropin hormone, the test device indicates a probable pregnancy. But pregnant women don't always produce the hormone at the same rate, so a woman could be pregnant but not yet producing enough hormone to prompt the signal from that particular test. Also, levels needed to trigger the signal vary among the different brands of the device. Thus, a test might indicate no pregnancy in a woman who, in fact, is pregnant. If the woman continued certain practices potentially harmful to the fetus, such as smoking, drinking excessively, or taking certain medicines, she might risk her baby's health.
After a negative pregnancy test, therefore, a woman should wait the number of days suggested in the instructions and test again -- making sure she's following the instructions properly. If the second test is negative and she's still not menstruating, she should promptly consult her doctor.
In other words, it can be risky for consumers to consider test results as a definite diagnosis. Professional follow-up is needed.
A doctor's diagnosis involves evaluation of the patient's medical history and physical examination, often other tests, and sometimes consultation with other medical experts. Further, unlike home testing, professional laboratories must meet quality standards which provide additional reliability an uniformity to test results.
A number of tests unavailable over the counter at pharmacies can be bought from medical supply firms without a prescription.
"Consumers should be wary about buying these tests on their own," Gutman says. "Many such products, though non-prescription, are intended for use by trained professionals, or for home use only with medical guidance."
However, interpreting results of the newer OTC tests on pharmacy shelves should not be a problem for consumers. Before FDA will approve OTC sales today, test sponsors must prove that consumers can accurately interpret results.
OTC tests also must be labeled with appropriate warnings. For instance, if a test is not for use by people with diabetes, a large-type warning must state so.
To use in-home tests as safely and effectively as possible, consumers should carefully read the instructions, which FDA makes sure are user-friendly. As Gutman puts it: "Instructions tell how a test works, when it works, when it doesn't, and what to do when it doesn't."
RELATED ARTICLE: Using Tests Wisely
To use an in-home test as safely and effectively as possible, take -- these precautions:
* Check the expiration date. If the date is past, don't buy the product. Chemicals in an outdated test may no longer work properly, so the results may not be valid. Don't use a previously purchased test with an expired date.
* Don't leave a temperature-sensitive product in the car trunk or by a sunny car window in hot weather on the trip home from the store. Don't leave it in the car if you go elsewhere.
* Follow the package directions on where to store the product at home.
* Don't guess if something is unclear. Consult a pharmacist or other health professional, or check the instructions for an "800" number.
* Note special precautions, such as avoiding physical activity or certain foods and drugs before testing.
* Follow instructions exactly, including any specimen collection process. Sequence is important. Don't skip a step. If a step to check the test or calibrate an instrument is included, do it.
* When collecting a urine specimen with a container not from a kit, wash the container thoroughly, and rinse out all soap traces -- preferably with distilled water, which generally is purer than other bottled or tap water.
* When a step is timed, be precise. Use a stopwatch or a watch that counts seconds.
* Note what to do if the results are positive, negative or unclear.
* Keep tests containing chemicals, which may be poisonous, or sharp instruments out of the reach of children. Promptly discard used materials as directed.
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|Title Annotation:||includes related information on how to use home diagnostic tests|
|Publication:||Nutrition Health Review|
|Date:||Sep 22, 1995|
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