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Study finds biotin interference

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Study finds biotin interference

A study published Sept. 26 in JAMA found that biotin ingestion was associated with potentially clinically important assay interference in some but not all of the biotinylated assays studied.

The study assessed the association of seven days of 10 mg daily biotin ingestion with the performance of 37 assays that measure 11 hormone and non-hormone analytes: TSH, T4, T3, free T4, free T3, intact PTH, prolactin, NT-proBNP, and 25-hydroxyvitamin D in six healthy adults (two women, four men), and ferritin and PSA in the four men, using four assay systems.

“Biotin interference outcomes were significantly different between biotinylated assays (9 of 23 [39%]) and nonbiotinylated assays (none) (Fisher exact test, P=.007),” Danni Li, PhD, and colleagues write (318[12]:1150–1160). The study was conducted at the University of Minnesota, Boston Medical Center, Children’s Mercy Hospitals in Kansas City, Mo., and Johns Hopkins Medical Institutions.

“Among the 23 biotinylated assays studied,” the authors write, “biotin interference was of greatest clinical significance in the OCD

Vitros TSH assay, where falsely decreased TSH concentrations (to

The smaller changes seen in other assays (OCD Vitros PTH; Roche Cobas e602 TSH, total and free T3, free T4, and 25-OHD; and Siemens Vista free T3) primarily produced false results within the reference range. But the authors note that those results could lead to falsely normal or abnormal interpretations for individuals who start from baseline levels closer to the reference range limits.

Biotin interference with clinical laboratory test accuracy is a complex issue, says Dr. Li, assistant professor and director of clinical chemistry, University of Minnesota Medical Center Fairview. “It depends on biotin dose, the clinical test, last dose of biotin, and renal function of a patient as biotin is cleared by kidney. Furthermore,” she tells CAP TODAY, “some diagnostic companies’ assays are more affected than others. And the million-dollar question remains: What is the oral biotin use prevalence in the United States?”

The FDA is reluctant to tackle this issue, she says, because the prevalence data are not available and it’s unclear to the FDA what specific questions it should address. “Should FDA’s role only be to make sure whether package inserts state that biotin is one of the interfering substances, or should FDA play a more active role in making sure companies provide clear instructions on what to do with patients who take large doses of biotin?”

The job of the clinical laboratory community, in Dr. Li’s view, is “to come up with clear and easy-to-follow recommendations for clinicians regarding what they should do.”