Clinically Significant Lab Errors due to Vitamin B7 (Biotin) Supplementation: A Case Report Following a Recent FDA Warning

Abstract

A 67-year-old female with a past medical history of multiple endocrine issues presented for follow-up subsequent to abnormal routine blood testing results. These included low thyroid stimulating hormone (TSH), low parathyroid hormone (PTH), and mildly elevated calcium levels. The presence of hypercalcemia and accompanying low PTH raised the concern for malignancy, while the depressed TSH indicated hyperthyroidism. Review of the patient’s medications revealed daily supplementation with 5 mg of vitamin B7 (biotin). The biotin was discontinued after suspecting the supplement was interfering with the patient's lab values. The labs were repeated one month later. The results showed normalized TSH, PTH, and calcium levels. The increasingly wide-spread use of biotin supplementation and the use of biotin as a component in many of the most common clinical assays has led to a trend of lab errors due to biotin interference. While some physicians are aware of the possibility of skewed results, steps need to be taken to prevent misdiagnosis. This includes ensuring that information about this issue is more widely disseminated, accurately accounting for a patient’s supplement use, reconciling proper clinical correlation with lab results, and promptly reporting when biotin is determined to be the cause of otherwise unexplained lab errors.

Biotin induced biochemical hyperthyroidism: a case report and review of the literature

“…The potential medical issue is that supra-physiologic biotin intakes can cause spurious results in streptavidin/biotin-based immunoassays used for routine clinical laboratory tests [ 4 ]. While the amount of biotin naturally received through dietary means is not enough to interfere with clinical tests, the levels found in these supplements can generate significant errors [ 2 ].…”

“…Biotin is small and thus able to bind to a wide variety of molecules without altering their chemical properties [ 2 ]. The streptavidin/biotin complex represents one of the most robust non-covalent interactions in nature.…”

“…The patients’ abnormal blood results would not be reflected in the patient, who is likely to be asymptomatic. Therefore, it is crucial to maintain a high index of suspicion and ask about biotin supplementation levels when an otherwise asymptomatic patient presents with abnormal results [ 2 ].…”

“…Biotin remains an under-recognized cause of abnormal lab results. These lab errors can cause emotional strain on the patient, lead to costly and unnecessary work-ups, and potentially harmful and unnecessary interventions [ 2 ]. It is worthwhile to rule out biotin supplementation before diagnosing abnormal thyroid function (especially before irreversible treatments such as radioactive iodine ablation).…”

“…If a patient insists on taking high dose biotin, they may do so without affecting thyroid function tests if they hold it long enough before doing the labs [ 6 ]. The biotin should be discontinued for at least 48–72 h before thyroid assaying by any commonly used biotin-streptavidin immunoassay [ 2 ].…”