Biotin supplement interference with immunoassays for parathyroid hormone and 25-hydroxyvitamin D in a patient with metabolic bone disease on maintenance hemodialysis.

Biotin (vitamin B7) is a dietary supplement that can lead to falsely abnormal endocrine function tests. The impact of biotin on both 25-hydroxyvitamin D [25(OH)D] and intact parathyroid hormone (iPTH) have not been previously described in end-stage renal disease (ESRD). A woman with ESRD on hemodialysis taking biotin 10 mg daily had a 25(OH)D spike from 25 to >100 ng/mL and an iPTH decrease from 966 to 63 pg/mL. After discontinuation of biotin, her 25(OH)D and iPTH returned to baseline. Biotin can cause erroneous 25(OH)D and iPTH results in ESRD that could adversely affect patient care.