Americans buy about $3 billion worth of home health kits every year. They're medical tests for the do-it-yourselfer.

There are more than 500 home health testing kits on the market today. Blood sugar testers have been around for years, but now you can also check your cholesterol or find out if you have any allergies.

But should you skip going to the doctor and take a home health test instead?

The skeptics at the Good Housekeeping Research Institute decided to take a closer look at the the growing trend.

Toni Hope, the institute's health editor, says in a recent survey, half of the people said they would try out a test instead of calling the doctor.

"There are all kinds of tests out there now, everything from allergies, to thyroid, to menopause," she said.

Home menopause kits claim a simple urine test can help determine whether a woman's period changes are caused by menopause. Dr. Michele Warren with the Columbia University Medical Center says it doesn't always work that way.

"The problem with these tests is that the levels of FSH, which are measures (that) vary tremendously in a normal cycle," she said. "So if you don't measure them exactly at the right time, it may give you an answer which suggests that you're in menopause when you're not."

Dr. Clifford Bassett, vice chair of the American Academy of Allergy, Asthma and Immunology, says a home allergy may be able to tell you what you're allergic to. But if you need a more thorough test, you should see a doctor.

"Sometimes these home allergy tests kits may test for a variety of common allergens -- cow's milk, egg and wheat. That's all they test for.

"In the office we want to focus on the most important allergens that affect an individual -- the type of pollen, the type of food that may be causing an allergic reaction," he said.

Good Housekeeping had volunteers test their cholesterol using home kits, then compared results from a professional lab.

"We found that the scores from Cholestrak came closest to the ones from the professional lab, but that test just gives you total cholesterol, not the breakdown of other kinds that you would need to really assess your risk for heart disease," Hope said.

If you do decide to play doctor at home, Good Housekeeping recommends discussing the test results with your physician.

Here's something else to keep in mind. It might seem cheaper to buy a home cholesterol test kit, but that's not always the case.

If you have health insurance, the test done by your doctor might cost you as little as your co-pay. And the report will be a lot more detailed than what you get with the home test kit.

Be advised: there is only one product currently approved by FDA and legally sold in the United States as a home testing system for HIV. This product is a kit marketed as either "The Home Access HIV-1 Test System" or "The Home Access Express HIV-1 Test System."

The kit is a home collection-test system that requires users to collect a blood specimen, and then mail it to a laboratory for professional testing. No test kits allow consumers to interpret the results at home.

More Information:

Vital Facts About HIV Home Test Kits