Biotin May Alter Thyroid Test Results

In a recent case report from Mass General Hospital, a male patient was erroneously diagnosed with Graves’ Disease. The diagnosis was made after blood tests revealed a suppressed TSH, and elevated T3 and T4. However, the patient had no clinical evidence of thyroid problems. Ultrasound of the neck showed a normal-sized thyroid with no nodules. The patient was questioned again about his medication list. He admitted to recently starting on high dose biotin. The patient was asked to stop the biotin and labs were repeated 2 weeks later with completely normal results.

Biotin, or Vitamin H, has long been reputed for its benefits in treating hair and nails. While many people take 5,000-10,000 mcg daily for their hair loss (that’s 5-10mg), the daily requirement is just 30-100 mcg (.03-.1mg). In many labs, thyroid testing is performed using the streptavidin-biotin immobilizing system. Streptavidin, a protein produced by Streptomyces avidinii, binds biotin with more affinity than other haptens. In a complex interplay, large biotin excess can result in reduced binding of the immune complexes to the solid phase, and thereby a falsely low TSH level. Based on this data, it is helpful to stop biotin for two full days prior thyroid testing.

Citation:
Barbesino, G. Misdiagnosis of Graves’ Disease with apparent severe hyperthyroidism in a patient taking biotin megadoses. Thyroid. 2016: 26;352:i1541.