Unbeknownst to many patients, the desire for thicker hair and stronger nails might be compromising the accuracy of their laboratory tests. Many immunoassay methods for a variety of different tests use a biotin-streptavidin interaction, and the assay package inserts include a warning about biotin ingestion affecting results.

However, the popularity of nutritional supplements containing hundreds of times more biotin than the recommended daily allowance and new therapeutic uses of biotin have made biotin interference a hot topic among clinical laboratorians, in vitro diagnostic manufacturers, and physicians. On Wednesday, a brown bag session, “Biotin-Related Interference with Immunoassay Methodologies,” took a detailed look at this growing concern. Randal Schneider, PhD, discussed the role of biotin in immunoassays, the effect of high concentrations of biotin on different immunoassay methods, and the lack of rigorous scientific studies that examine biotin interference.

After years of only sporadic mentions in the literature, commentary and case reports about this phenomenon have increased notably. Schneider attributed two factors to this increased interest. “One is more awareness of the issue by clinicians,” Schneider said. “The other is that people are consuming large doses of biotin.”

Advertisements for supplements promising healthy hair, skin, and nails are rampant. Yet most clinicians are not aware that biotin is a potential interferent in the tests they order. In addition, patients might not realize that the supplements they take contain biotin, much less high concentrations of this B-complex vitamin. Consequently, even when clinicians know about the potential for interference, they sometimes get incomplete information from patients.

Biotin is not just an over-the-counter supplement. Some clinicians prescribe high concentrations for conditions ranging from biotinidase deficiency to multiple sclerosis. However, if a different clinician orders laboratory testing without knowing about this prescribed high-dose biotin, the situation is ripe for misinterpreted results.

Most case reports have focused on commonly ordered thyroid hormone tests, but any analyte that relies on a biotin-streptavidin interaction might be affected. Results for tests like cardiac troponin or human chorionic gonadotropin could have serious consequences for patient care if a biotin interference goes undetected.

What should clinical laboratories do? In the morning session, all of the attendees who worked in a clinical setting said that had have encountered a case of biotin interfering with a patient’s result. Schneider recommended that each laboratory work with manufacturers of assays that might have biotin interference and ask for recommendations both on the amount of biotin that might cause an interference as well as the time that needs to elapse between biotin ingestion and clinical testing.

Laboratorians must understand how biotin could affect their assays as well as any associated clinical consequences. Assay format dictates the effect that biotin interference could have: Competitive assays show a false increase while non-competitive assays yield false decreases. For each analyte, laboratories should determine whether there is an interference and if so, whether it is clinically relevant.

One attendee, Raffick Bowen, shared that his institution was adding a comment to all immunoassay results that could be affected by biotin. The spirited discussion that followed indicated that there is not a single fix that will work in all situations.

Given the number of assays potentially affected and the range of possible effects, biotin interference presents an excellent chance for laboratorians to work with clinicians to ensure accurate patient results. “This is a really good opportunity for laboratory professionals to showcase how they can assist with patient care,” Schneider said.