The good and bad of at-home medical tests

Home medical tests have long been available to consumers, to some extent. Modern pregnancy tests hit shelves in the 1970s, and home glucose testing dates back to the 1950s. But in recent years, the variety of tests, as well as their popularity, has soared. Today, home medical testing is an $11 billion industry.

"It's hard to resist the lure of information," says primary care physician Daniel Chandler, M03, associate professor at Tufts University School of Medicine and associate chief medical information officer at Tufts Medical Center. "Some home tests are great, and they can expand access to knowledge about your health. But certain tests are well known to be more reliable than others."

For example, the pregnancy tests sold at the pharmacy are the same as what's used in Chandler's clinic. And home tests for influenza and COVID-19, which introduced and normalized the process of home medical testing for many people during the pandemic, are "very, very accurate," Chandler says.

However, these days, home tests exist for a wide array of ailments, from urinary tract infections and sexually transmitted diseases to inflammation and hormone levels.

But as the saying goes: just because you can, doesn't mean you should.

"I love that people want to figure out why they're not feeling well or want to stay healthy, and I want to encourage that aspect," says Harmony Allison, an assistant professor at Tufts University School of Medicine and gastroenterologist at Tufts Medical Center. "But some of these are expensive tests, and they can end up causing more anxiety than helping people understand what's going on with their health. The testing process should really be in partnership with a doctor."

Here are more things Chandler and Allison want patients to keep in mind about home medical tests.

Some results are more useful than others

Knowing that you're positive for influenza or COVID-19 can be valuable information in terms of containing the spread of illness. For example, it might help you decide to work from home or delay a visit to an elderly relative. You could call your doctor for medicine, but if you don't feel too sick, you may not need it. But not all home tests provide clear-cut results with actionable next steps.

"Hormone levels are something people often want to know about, but are probably the least beneficial to know about, because they tend to fluctuate day-to-day, and sometimes even minute-to-minute," Chandler says.

Many variables contribute to hormone test results. For example, usually, cortisol levels spike in the morning, go down as the day progresses, and are at their lowest levels at night in the middle of sleep. The timing of when the home test is taken, specifically how soon after waking up, will affect the results.

Some home hormone tests are sweat tests, which require the patient to wipe their skin to gather sweat. Chandler calls these tests highly unreliable, because it's hard to predict how much sweat someone will have on their skin at any moment.

Home hormone tests can also be falsely reassuring to women who want to answer the question of whether they're in menopause. If the hormone levels happen to come back as low, there's no context to indicate if they're low as part of normal fluctuation or low because someone is in menopause. Chandler encourages patients to see a doctor for help with their symptoms, rather than take the test without a physician's support.

Home test results aren't always helpful

When physicians order a test, they have a specific question they hope to answer. If a patient has a hacking cough and the doctor hears crackling while listening to their lungs, an X-ray can answer the question of whether they have pneumonia. Home tests work in a similar way, Allison says.

"Say someone is curious about whether they have any food sensitivities, so they pay up to a few hundred dollars for a home food sensitivity test. The test shows that they may have lactose sensitivity, but they normally drink milk every day without issue," she says. "So, what does that mean, and was this information helpful to the person taking the test?"

Allison relies on a more useful—and less expensive—process to diagnose lactose sensitivity: Drink a cup of milk every day for a week and take note of symptoms such as diarrhea or gassiness. Then stop the milk for a week and see if the symptoms go away. Then start the milk again, and if the symptoms come back, you have lactose sensitivity.

Some tests are just plain unreliable

Gut microbiome tests present challenges for doctors, Allison says. Patients have told her they've taken a microbiome test that showed they were at increased risk for different conditions, like Alzheimer's disease.

"It's hard, because the testing company sends the patient very official-looking communication that states they're at increased risk for X, Y, and Z, and the patient is concerned," Allison says. "As doctors, we have to explain that we don't know if the test was reliable, or if the lab was accurate, or what the results mean."

Chandler says that when patients hand him test results from an unknown lab, such as blood tests, he inevitably repeats the tests himself. He also says that sometimes, the least health-literate patients are the most likely to be taken advantage of.

Regulation exists, but there are loopholes

The U.S. Food and Drug Administration (FDA) is one of multiple organizations that regulate medical tests. While FDA regulation does not necessarily mean a test has perfect accuracy, it does guarantee a highly consistent result.

Clinical laboratories are often certified through CLIA, or the Clinical Laboratory Improvement Amendments of 1988. CLIA-certified labs are held to a certain standard around lack of variability in test results. Tests for things like electrolytes, kidney function, diabetes, and cholesterol require virtually 100% perfection and very low variability.

If a home medical test company chooses not to go through the process of getting regulatory approval, there are usually two reasons, Chandler says. One is that it's an expensive process, and they may not have the funds. But more commonly, it's because the company isn't sure the product will pass.

"I would love to see an improvement in the reliability of these at-home tests, because I think they can save the health care system money, time, and effort," says Chandler. "But I hope people use these tests in partnership with a primary care physician, as opposed to instead of. Your doctor is always going to be a better answer than most at-home tests."

Provided by Tufts University