Biotin Interference

Biotin is a water-soluble B-complex vitamin that plays an important role in cell growth and food metabolism. This vital nutrient is found in high-protein foods, including meat, soybeans, nuts and lentils. Biotin is also in prenatal vitamins and multivitamins. Recently, biotin has gotten much attention for its purported hair-, nail- and skin-enhancing properties, making it a popular standalone supplement marketed specifically for these purposes. While clinical evidence supporting this claim is limited, it hasn’t stopped increasing numbers of people from buying off-the-shelf products containing biotin in search of promised results.

Although biotin is included in multivitamins, most people don’t need supplementation in order to meet their biotin needs. The daily adequate intake (AI) for biotin for adults over 19 years old is 30 µg,¹ as established by the Food and Nutrition Board. The AI for pregnant women is 35 µg.¹ 

Over-the-counter biotin supplements contain as much as 10,000 µg, greater than 300 times the daily recommended intake. Biotin is sold under various names: vitamin H, coenzyme R or vitamin B7. Pharmacokinetic studies have shown that serum concentrations of biotin can reach up to 300 ng/mL when taking supplements containing 20 mg biotin² or 1,160 ng/mL for patients taking doses of biotin up to 300 mg.³ Note that these studies were performed in healthy individuals: clearance of biotin could be different in individuals with renal impairment, with resulting prolonged concentrations of biotin or higher peak concentrations. 

Biotin is used together with streptavidin in the design of many diagnostic assays. These assays leverage the high stability and specificity of the biotin-streptavidin interaction as a means of increasing analytic sensitivity. Examples of assays that may use biotin-streptavidin chemistry include those that measure cardiac biomarkers and hormones.

All assays that use biotin-streptavidin chemistry are theoretically susceptible to biotin interference, but biotin levels associated with normal dietary intake are not high enough to affect results, whereas the high serum levels associated with dietary supplements may. Certain types of biotin-streptavidin assays are more susceptible than others, with the most vulnerable being those in which the biotinylated reagent is bound to the solid phase in the presence of the patient sample. In sandwich assays, excess biotin can displace biotinylated antibodies, yielding erroneously decreased assay results. In competitive assays, excess biotin competes with the biotinylated analog for streptavidin binding sites, yielding erroneously increased results.

The FDA has outlined recommendations for consumers, clinicians, healthcare providers and laboratories on this subject.⁴ 

For consumers, the recommendation is that those using biotin supplements or adding biotin to their diets inform their doctors.

For clinicians and healthcare providers, recommendations include asking patients whether they are taking biotin and instructing them to refrain from biotin before testing. For most patients, the half-life of biotin is very short—under two hours. Within four to five half-lives, biotin is 99% cleared from the body.

Laboratories are encouraged to ask patients about biotin use at the time of sample collection and to work with diagnostics manufacturers to understand the extent to which biotin affects assays. Fully understanding the degree of interference that may result from excess biotin in a sample is complex, as interference depends on dose, renal clearance, and assay design. 

We continue to test assay performance to gain greater insight into the effects of biotin on specific diagnostic tests and their results. See Tech Docs section for information on biotin-remediated products.