The doctor is in -- the mailbox, that is.

You can now do self-administered tests for everything from thyroid function to HIV in the privacy of your own home -- and that list continues to grow, as the Food and Drug Administration recently approved the first at-home cervical cancer test.

While the tests can make it easier for people to access health care and can be helpful for those who have extreme anxiety about sensitive or invasive medical exams, experts warn that most of the tests cannot replace an actual in-person visit.

Here's what doctors say you can test for at home, and when you should make the trek to your physician's office.

There are two kinds at "at-home tests."

In one type, the patient collects the sample and sends it off to a lab; the new cervical cancer test is like this.

The other gives an instant result -- think COVID-19 and pregnancy tests.

HIV home-testing kits can improve rates of diagnosing sexually transmitted infections in rural communities and help people who are nervous about going to the doctor to seek a sensitive test, said Dr. Joseph Cherabie, an infectious diseases specialist in St. Louis.

"You really want to get people to care as quickly as possible, but some people could be very anxious about that results as well," Cherabie said. "And they have very negative reactions."

Labs are required to report a positive HIV test, instead of putting the onus on the patient who took the test, Cherabie said, and and, often, the patient is matched up with HIV support services.

"If you are part of a sexual and gender minority community, going to a doctor's office can be full of a lot of historical trauma, and you may prefer to just do testing at home without anyone judging you or asking you invasive questions about your sex life," Cherabie said.

The new cervical cancer test -- which tests for strains of human papillomavirus, or HPV -- involves a testing swab that's like a tampon, said Dr. Susan Modesitt, a gynecologic oncologist at Emory University in Atlanta.

It is not, Modesitt said, a replacement for a Pap smear, the exam in which a metal speculum is inserted in the vagina to scrape cervix cells. A doctor's visit also involves a pelvic exam, a chance to talk about abnormal bleeding -- a sign of endometrial cancer -- and other symptoms and issues, like menopause or STIs.

"There are so many other reasons to see your doctor and get an exam outside of a cervical cancer screening," she said.

Some at-home tests can replace a trip to the doctor's office. That's especially true in rural areas, where it can be difficult to get a colonoscopy.

"The colonoscopy requires a pre-op, and you have to drive maybe 70 miles for it," said Dr. Steven Furr, board chair of the American Academy of Family Physicians who practices in rural Alabama. "You get anesthesia. It's actually almost like a surgical procedure in many ways.

"So, for a lot of people, that's pretty arduous. That's where an at-home test can come in handy."

But, Furr said, if your test reveals issues, you need to go to your doctor. Plus, patients should always discuss test results with their physician instead of interpreting them on their own, he said.

If you have symptoms of what you're testing for, go to the doctor.

At-home colon cancer tests aren't the right option for people with a history of colon cancer or high-risk conditions, such as inflammatory bowel disease, said Dr. Zachariah Foda, a gastroenterologist at Johns Hopkins. He added that they're also not recommended for people who are having GI symptoms.

While there are tests for many things -- running anywhere from $15 to $400, depending on what is being evaluated -- Furr said it's essential to make sure that your test is FDA-approved so you can better trust the results.

"Anytime we get people involved in their own health care and help them understand what's going on, I think that's a good thing and it gives us a chance to talk," he said. "Any kind of screening is better than no screening."

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