special supplement to the January/February issue of Clinical Laboratory News illustrates how easy it is for a megadose of biotin to trick clinicians into believing that a patient has Graves’ disease.

Taken at appropriate levels, biotin won’t interfere with lab test results, Julie Kirkwood writes. “However, biotin supplements are sold in doses that far exceed this amount, from 1 mg to 100 mg, and people sometimes take the pills multiple times a day,” she explains. Studies have indicated that the supplement in very high doses might be useful in treating multiple sclerosis. However, the downside is these high doses are unintentionally skewing lab results among some patients.

Biotin interference has drawn attention from health experts and regulators alike. CLN in December 2016 addressed this important topic in a Bench Matters article. “At least three papers have looked at this phenomenon, and my endocrinology colleagues and I are seeing more instances of it. However, I do not think the medical community at large is at all aware of this issue. Laboratorians have an important role in consulting with physicians who see immunoassay results that do not match their patients’ clinical presentation,” observed the author, Giuseppe Barbesino, MD, an assistant professor of medicine at Harvard Medical School.

A year later, the U.S. Food and Drug Administration (FDA) issued a warning about biotin’s potential interference with lab tests. “Biotin in blood or other samples taken from patients who are ingesting high levels of biotin in dietary supplements can cause clinically significant incorrect lab test results. The FDA has seen an increase in the number of reported adverse events, including one death, related to biotin interference with lab tests,” FDA’s notice stated.

Biotin interference affects a number of tests critical to internal medicine, Earle W. Holmes, PhD, DABCC, director of the Loyola University Medical Center special chemistry, immunoserology, and endocrinology laboratories in Hines, Illinois, tells CLN. In a literature review, Holmes and his colleagues found 17 reported cases of biotin interference with thyroid assays that had taken place in recent years.

The cases involved children who’d been incorrectly diagnosed with Graves’ disease and had started biotin therapy to treat familial metabolic diseases. Several of them were 2 years old or younger and had already started anti-thyroid therapy. “I think that there are other perfect storms out there, in which biotin interference with several different tests could provide compelling lab evidence for a diagnosis that might not be correct,” Holmes tells CLN.

The unpredictability of biotin interference makes it a difficult problem to solve. In one study, 10 mg biotin supplements ended up interfering with the results of several tests that could have led to a series of misdiagnoses involving congestive heart failure and thyrotoxicity. “Yet several biotin-based assays that were predicted to experience interference did not,” Kirkwood writes.

Laboratorians differ in their opinions on how to address biotin interference, provoking concerns that this could become a legal issue. As Kirkwood explains, manufacturers of biotin might have to reconfigure formulas and issue warning labels on products.

Holmes’ lab responded by conducting studies to estimate the thresholds for biotin interference in several tests at high risk for interference and estimating how long patients should hold off on taking biotin before a blood test. Kirkwood describes how his lab started attaching biotin warnings not just for test results but also at the point of entry at Loyola’s electronic medical record system.

Pick up the January/February issue of CLN to learn more about how labs and clinicians have been working together to detect biotin interference and prevent misdiagnoses.