Biotin Interactions

High-dose biotin (vitamin B7) interferes with biotin-streptavidin-based immunoassays used to measure cardiac troponin, producing falsely low results that can mask an evolving heart attack. The FDA has received reports of patient harm, including one death linked to a missed myocardial infarction diagnosis caused by biotin-altered troponin readings.

High-dose biotin interferes with biotin-streptavidin-based immunoassays used to measure TSH, free T3, free T4, and thyroglobulin, producing a falsely low TSH and falsely elevated free thyroid hormones, a pattern that mimics Graves' disease. Patients have been incorrectly diagnosed with hyperthyroidism and started on antithyroid drugs because of biotin interference.

Carbamazepine reduces biotin status by inhibiting sodium-dependent biotin uptake in the intestine, decreasing renal reabsorption, and accelerating biotin catabolism through enzyme induction; long-term users often have measurably lower plasma biotin and elevated organic-acid markers of biotin insufficiency.

High-dose biotin (B7) does not directly interact with levothyroxine pharmacologically, but it interferes with biotin-streptavidin immunoassays used for TSH, free T4, free T3, and thyroglobulin. This can produce falsely low TSH and falsely high T4/T3, mimicking hyperthyroidism and leading to inappropriate dose reductions.

Valproate appears to reduce biotinidase activity and impair mitochondrial biotin handling, leading to subnormal biotin status that has been linked to the drug's signature alopecia (hair loss) and brittle nails; biotin supplementation has reversed hair loss in case reports.