For decades, home pregnancy tests have allowed the worried and the hopeful to find out – in private – whether a baby is on the way.
For years, people with diabetes have been able to monitor blood sugar levels, with increasingly sophisticated test kits, and adjust their insulin accordingly.
You can test yourself at home to see if you’ve ovulated, to learn if there’s hidden blood in your stool or urine, or to see if you have a urinary tract infection, high cholesterol or soaring blood pressure.
You can even, thanks to a recent decision by the US Food and Drug Administration, monitor how fast your blood clots – a potentially huge boon to the 1.5 million people who take blood-thinning drugs for heart rhythm disturbances and other problems.
Because of ever-improving technology and consumer demand, the home test industry is now a $ 1 billion a year business that’s growing at 12 to 13 percent a year, according to two market research firms, the Freedonia Group, Inc. in Cleveland and Frost & Sullivan in Mountain View, Calif.
The question is, is all this self-monitoring a good idea?
The answer, perhaps surprisingly, is a cautious yes – with some important caveats.
Used correctly, home testing can save endless trips to the doctor to monitor an ongoing problem. It can also save money – most kits range from a few dollars to $ 150 – and help you feel in better control of your own health. And you can often catch little problems, like a worrisome trend in clotting time or blood sugar levels, before they become big ones.
“If you are in a relationship with a health care provider and have a clear indication for how to use a test, this stuff can be superb,” says Dr. Gary Horowitz, director of clinical chemistry at Beth Israel Deaconess Medical Center.
On the other hand, virtually all tests have pitfalls, especially the kind that you interpret yourself. You may get “false negatives” that show you’re fine when you’re not, and “false positives,” showing the opposite.
And if you’re an amateur at the art of test interpretation, you may needlessly worried about a seemingly “bad” result – like low blood sugar upon awakening, which is normal – or falsely reassured when you should seek professional help.
That said, many home tests do vastly more good than harm.
Home monitoring “has revolutionized the care of people with diabetes, making it possible for people to be much more pro-active in taking care of themselves minute to minute,” says Dr. Edward Horton, vice president and director of clincal research at the Joslin Diabetes Center in Boston.
Taking frequent finger-stick tests to measure blood sugar levels and then eating or taking insulin to keep those levels within a safe range has enabled many diabetics to avoid complications such as damage to the retina, kidneys and nerves, according to a 10-year, multi-center study completed in 1993.
And noninvasive glucose tests are in the pipeline, including a yet-to-be-approved infrared device that eliminates the need to draw blood from a finger, according to the Health Industry Manufacturers Association.
Better technology has also made home blood pressure kits more reliable, says Dr. Michael Weber chairman of the department of medicine at Brookdale University Hospital in Brooklyn, N.Y.
Until a couple of years ago, he says, home blood pressure kits were often inaccurate. In fact, the American Heart Association still does not take a position on the kits for either blood pressure or cholesterol.
But some doctors feel the kits are helpful. “You can depend on those numbers,” says Weber, though he warns that those who monitor their own blood pressure should never alter their medication dosage without checking with a doctor.
Dr. Irene Gavras, a hypertension specialist at the Boston University School of Medicine, emphatically agrees, adding that you should not use the kits to diagnose yourself but only to monitor a problem already diagnosed by a doctor. And you should have a health care professional check your home blood pressure kit for accuracy before you use it.
Home cholesterol testing, on the other hand, may be not wise.
“I’m against checking it at home for many reasons,” says Gavras, noting that the kits use a tiny drop of blood from the finger and provide only one number: total cholesterol.
“This is essentially useless,” she says, because you need to know your levels of “good” and “bad” cholesterol and triglycerides, or fat molecules, as well.
If you find your cholesterol is higher than the desirable 200 milligrams per deciliter or less, you may panic, even if you have lots of good cholesterol. Or your home test may show your overall cholesterol is fine, even though you have too much bad cholesterol.
Being your own doctor can be risky also because you may miss a problem you’re not worried about.
“You may think your major risk is heart disease. So you measure your cholesterol and find it’s normal. But what you’ve got on your back is a melanoma that no one sees,” says Horowitz. “Or if you’re having trouble getting pregnant, you may spend months using an ovulation detection kit when the problem lies elsewhere.”
And testing for some diseases, like HIV, can be upsetting. In part because of this, the FDA has not allowed HIV home test kits on the market, although it has approved two kits that allow patients to draw blood, which they then send to established labs for testing.
(About 10 days ago, however, one of those kits, Confide HIV, made by Johnson & Johnson, was taken off the market because of the lack of demand.)
Even the straightforward pregnancy test is not always as simple as it seems, says Dr. Joseph Pinzone, a research fellow in medicine at Massachusetts General Hospital.
If it’s positive, you need to see a health care provider to get pre-natal care. But if it’s negative and you’ve missed some menstrual periods, you need to see a doctor anyway to find out why. On the other hand, many people like the convenience of finding out on their own and then making a doctor’s appointment.
Dr. Steven Gutman, director of the division of clinical laboratory devices at the FDA, says that all the kits now on the market had to pass two hurdles prior to approval: They were shown to work in the hands of the average consumer and the benefits of home testing outweigh the risks.
Sometimes, as with two new prothrombin tests that measure how fast blood clots in people on anti-clotting medication, the FDA approves a home test with a condition: Patients need a doctor’s prescription to get it.
This ensures that patients learn to use the test properly and that a doctor helps interpret the results, and it lessens the chances that a patient will change the dosage of medication, says Gutman. Taking too much of a blood-thinner like Coumadin can lead to serious bleeding; taking too little can lead to dangerous blood clots.
“No test is perfect,” says Gutman. “If you have a health problem that you’re worried about, it doesn’t matter if you test positive. If it’s bothering you, go see a doctor.”
Tips for using home test kits
- Read the label carefully. The FDA requires the makers of home test kits to write labels that anyone with an 8th grade education can understand. But well-written labels do no good if you don’t read them.
- Be precise. If the test involves careful timing, use a stopwatch or clock with a second hand.
- Keep accurate records of your results.
- If you have questions, don’t hesitate to call the “800” number listed on many home kits.
- Don’t use a home test result to change a medication or dosage unless your doctor has said it’s okay. (Many diabetics have been taught how to adjust their doses of insulin.)
- Don’t try to diagnose yourself with a home kit. The kits are useful for monitoring a condition you and your doctor know you have. But diagnosis is often trickier than monitoring, so call your doctor if you are worried about your health.
- If you buy a home blood pressure kit, take it to your doctor for an accuracy check. And before you buy a kit, make sure the store will give you a refund if it is not working properly. Make sure it’s calibrated right, something medical supply stores often do. And to avoid getting anxious about each tiny fluctuation, don’t use a kit more often than your doctor suggests. Inexpensive kits – about $ 30 – with which you listen through a stethoscope to the sound of your blood flowing, can often be just as good as more expensive electronic kits.
- Don’t use home cholesterol kits unless your doctor suggests it. It’s better to get a full “blood lipid profile” that includes measures of good and bad cholesterol and triglycerides from a health care provider. Once you have this, your doctor may want you to monitor total cholesterol at home.
- Remember that home test kits are a complement to an ongoing relationship with a doctor, not a substitute for it.
- And if a home test comes out negative but you still have symptoms? You guessed it – call the doctor.