Vitamin marketed for hair, nail growth can ‘fool’ medical tests, researchers warn

by NCN Health And Science Team Last updated on March 29th, 2019,

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.

“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 Amazon.ca. 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.

Biotin, also known as vitamin B7 or vitamin H, has seen a surge in popularity in recent years based on limited evidence that it enhances hair, skin, and nail growth. Due to its water-soluble properties, biotin is excreted through the urinary system and is considered nontoxic even at large doses. However, a high concentration of biotin in blood can interfere with laboratory tests that use technology dependent on biotin-streptavidin interactions. These tests include immunoassays used to investigate or monitor cardiac disease, endocrine disorders, malignancies, anemias, and infectious diseases. Increasingly, cases of erroneous laboratory results due to biotin use have been reported in the medical literature. The results can be falsely low or falsely high, and in either case can lead to patient misdiagnosis and mismanagement. Mitigation is possible when biotin interference is identified. Patients can be advised to discontinue the supplement before follow-up testing or physicians can order an alternative testing method. While laboratory professionals have been aware of biotin interference for many years, greater awareness among health care providers in general is needed to ensure that biotin supplementation is identified and mitigation strategies are considered.

High biotin concentrations in blood samples for immunoassays that employ biotin-streptavidin interactions can interfere with investigations for cardiac disease, endocrine disorders, malignancies, anemias, and infectious diseases and lead to falsely low or falsely high results.

Clinical and commercial use of biotin

Biotin, also known as vitamin B7 or vitamin H, is a water-soluble vitamin that serves as a cofactor for a number of carboxylase reactions, making it essential to the functioning of various metabolic pathways. It is involved in fatty acid synthesis, catabolism of branched-chain amino acids, gluconeogenesis, islet cell gene expression, insulin secretion, and the Krebs cycle.

The recommended dietary reference intake for biotin is 30 µg/day. The vitamin is found in various foods, including egg yolk, pork, liver, whole cereals, soybeans, avocado, cauliflower, and leafy greens. Because of its abundance in a typical North American diet, biotin deficiency is uncommon, and supplementation is rarely indicated.

Clinically, biotin may be prescribed in patients with malabsorptive disorders or in those on total parenteral nutrition. It may also be useful in relieving muscle cramps in hemodialysis patients. High doses of biotin (5 to 30 mg/day) are recommended in certain inborn errors of metabolism, such as in biotinidase deficiency, propionic acidemia, or in holocarboxylase synthetase disorders.More recently, mega-doses of biotin (up to 300 mg/day) have shown promise in secondary progressive multiple sclerosis.

In the past decade, biotin supplementation in doses up to 20 mg a day has been marketed to promote hair, skin, and nail growth. Although there is limited evidence to support this claim, marketing led to biotin sales of up to 49.6 million units in the US alone between July 2016 and July 2017. Biotin is currently the top-selling multivitamin supplement on Amazon.ca. Locally, a survey of 660 patients visiting the Diamond Health Care Centre Outpatient Laboratory at Vancouver General Hospital found that 50 respondents (7.6%) were taking biotin. The majority of users were female (92%) and biotin users tended to be younger than non-users: age 49 (19 to 85) years versus age 54 (19 to 98) years. The prevalence of biotin supplementation in the study survey population was similar to that reported by the Mayo Clinic, which found 7.7% of outpatients to be ingesting biotin.

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