Case: High-Dose Biotin Leading to Pseudohyperthyroidism in Multiple Sclerosis

A 55-year-old woman with multiple sclerosis and no history of thyroid disease developed lab abnormalities suggestive of thyrotoxicosis on routine testing.
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A case of pseudohyperthyroidism after taking high-dose biotin was reported in a woman with multiple sclerosis (MS). The data were presented at the ACTRIMS Forum 2018 in San Diego, California.1

The 55-year-old woman had no prior history of thyroid disease, but after taking high-dose biotin, laboratory test results were not normal and were suggestive of thyrotoxicosis. Her thyroid stimulating hormone (TSH) level was 0.032 uIU/mL (reference 0.45-4.5 uIU/mL) and her thyroxine T4 free-direct level was >7.77ng/dL (reference 0.82-1.77ng/dL).  

The patient was taking dimethyl fumarate 240 mg twice daily, low-dose naltrexone 4.5 mg, baclofen 30 mg, escitalopram 10 mg, vitamin D-3 5000 IU, vitamin B-complex, and biotin 300 mg. At the time of workup, the patient denied any mood irritability, sleep difficulty, tachycardia, heat intolerance, diarrhea, or weight loss.

The disconnect between the patient’s symptoms and laboratory values guided clinicians to a possible diagnosis of pseudohyperthyroidism. After stopping biotin supplementation for 3 days, repeat testing showed that thyroid levels had normalized, with TSH 2.46 uIU/mL and T4-free 1.1 ng/dL. To confirm the suspected diagnosis, the patient was re-challenged with biotin, which resulted in low TSH levels and high T4-free levels; these values normalized again after withholding biotin.

Biotin, an essential coenzyme in energy metabolism and fatty acid synthesis, plays a potential role in remyelination. A randomized, double-blind, placebo-controlled study further demonstrated sustained reversal of MS-related disability in patients with progressive MS who took high-dose biotin.2 Since then, its use among patients with progressive forms of MS has grown.

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The use of biotin, however, has been linked to cases of apparent hyperthyroidism likely attributed to its interference with thyroid assays.

The study authors concluded, “MS specialists should be aware of this phenomenon and should know how to differentiate pseudohyperthyroidism from true endocrine disease to avoid unnecessary testing or treatment.”

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  1. Hu NN, Shin RK, Tornatore C. Pseudo-hyperthyroidism in a multiple sclerosis patient taking high-dose biotin. Presented at: ACTRIMS Forum 2018; February 1-3, 2018; San Diego, CA. Abstract P075.
  2. Tourbah A, Lebrun-Frenay C, Edan G, et al. MD1003 (high-dose biotin) for the treatment of progressive multiple sclerosis: a randomised, double-blind, placebo-controlled study. Mult Scler. 2016;22(13):1719-1731.