Consumers will soon be able to bypass their doctors by going online to order cholesterol readings, thyroid tests and other bloodwork from the biggest diagnostics company in the U.S.

Laboratory Corp. of America Holdings will let customers go online to pay for tests, visit a service center to get blood drawn, then view the results on the Web. The company has already been doing back-office lab work for a number of Internet firms that let people order up tests without a doctor.

Rapid and at-home diagnostics are a growing corner of the health-care market, with businesses like WellnessFX Inc. and Direct Laboratory Services LLC tapping into demand from patients who want to get sensitive results in private or seek to monitor their health outside of the traditional doctor’s office. Companies like LabCorp are tapping into demand from consumers who want to measure their bodies to monitor the effects of exercise and healthy living and to learn about their potential risks of disease.

“We need to retake that territory for ourselves,” LabCorp Chief Executive Officer David King said in a telephone interview. “It’s a growth opportunity for us. It’s something consumers increasingly want to have access to, and it’s something we’re doing already and our capabilities are being utilized without us getting the benefit from a branding perspective.”

LabCorp is also facing competition as options emerge for consumers to get tests without visiting a service center at all. Startup Theranos Inc., founded in 2003, has developed a diagnostic kit available in some Walgreens locations that it says can provide a range of results, from lipid panels to the presence of HIV, with mere drops of blood.

Drugstore Partnership?

LabCorp’s direct-to-consumer business will initially be run online. The company is exploring a partnership with a drugstore chain as well -- an idea that rival Quest Diagnostics Inc. tried and scrapped. The company didn’t say precisely which tests it will offer or how much it will charge. In some states, the law will still require consumers to get a doctor to order tests.

The consumer appetite for health information is growing as devices like the FitBit and the Apple Watch offer more sophisticated ways to monitor the body, and as companies like 23andme Inc. clash with regulators over the interpretations they provide for genetic information.

“We have entered an era where there’s a lot more patient involvement in their health care,” said Steven Lamm, medical director of the Tisch Center for Men’s Health at New York University’s Langone Medical Center. “The concern is when you want to take control of your health without being properly informed about what you’re actually testing.”