The use of a popular vitamin supplement can interfere with medical tests and lead to a potential misdiagnosis, a recent report out of British Columbia is warning.

The report, released in the March edition of the British Columbia Medical Journal, indicates that a high level of biotin, also known as vitamin B7 or vitamin H, in the blood stream can impact the results of various medical tests, including those used to monitor cardiac disease, hormone disorders, blood diseases and certain infections.

The study indicates vitamin B7 can lead to falsely high or low test results, which can lead to a misdiagnosis.

“If the doctor doesn’t know someone has done this, the doctor could misinterpret the tests and think they had a condition that they don’t have,” Dr. Marshall Dahl, a clinical professor in the division of endocrinology at the University of British Columbia and one of the authors of the report, said in a phone interview with

“Doctors just have to be aware and patients need to be aware that if they’re taking high doses of the biotin, it might fool their lab tests.”

The report outlines the case of a 54-year-old woman who came to doctors with a suspected overactive thyroid. Tests identified what the woman suspected, but further questioning revealed she was taking high-dose biotin for her multiple sclerosis.

The woman was told to stop taking the supplement for a week before another test, which would later reveal the woman had a normal thyroid.

“If someone thought they had an overactive thyroid gland, they would’ve received medicine that they didn’t need,” Dahl said. “Because they didn’t really have a high thyroid, they would’ve gotten a really low thyroid, because (the treatment) would’ve brought them down.”

Biotin is a water-soluble vitamin required for a variety of bodily functions and is found naturally in eggs, pork, whole cereals, avocados and leafy greens. Researchers say biotin has seen a surge in popularity in the past decade as marketers of some products claim the vitamin can boost hair, nail and skin growth, despite limited scientific backing.

Biotin is currently the top-selling vitamin on An estimated 49.6 million units of the product were sold in the U.S. between July 2016 and July 2017.

Dahl stressed that taking biotin does not have an adverse effect on the human body, but it can impact some health tests.

He is advising physicians to always ask patients about their supplement-taking history before conducting a medical test. Patients should refrain from biotin products for at least a day before a blood test, or up to a week if taking high doses of biotin.