NutriStack
Methimazole and Vitamin B7, a caution.
Vitamin B7 can interfere with thyroid immunoassays used to monitor methimazole treatment. The pattern can mimic Graves' disease activity by making TSH look falsely low and T3 or T4 look falsely high on susceptible assay platforms. This can lead to unnecessary methimazole dose increases or delayed dose reduction.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Methimazole and Vitamin B7
- Pair type
- Caution
- Evidence (highest tier)
- Strong
- Source citations
- 3 sources
- Stack Score effect
- −5 to your Stack Score (per scored caution row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Caution · Strong evidence
Caution
What is happening. Vitamin B7 can interfere with thyroid immunoassays used to monitor methimazole treatment. The pattern can mimic Graves' disease activity by making TSH look falsely low and T3 or T4 look falsely high on susceptible assay platforms. This can lead to unnecessary methimazole dose increases or delayed dose reduction.
Mechanism. Biotin-streptavidin assay interference can produce false results in both sandwich and competitive immunoassays. In thyroid monitoring this can falsely suggest persistent hyperthyroidism even when methimazole is working.
Recommendation. Stop biotin for at least 48 to 72 hours before thyroid testing, and follow longer lab-specific instructions for high-dose biotin. Tell your prescriber and lab about all biotin-containing supplements before methimazole monitoring labs are interpreted.
Sources (3)
- Ylli D, Soldin SJ, Stolze B, Wei B, Nigussie G, Nguyen H, Mendu DR, Mete M, Wu D, Gomes-Lima CJ, Klubo-Gwiezdzinska J, Burman KD, Wartofsky L. Biotin Interference in Assays for Thyroid Hormones, Thyrotropin and Thyroglobulin. Thyroid. 2021;31(8):1160-1170. PMID 34042535
- Piketty ML, Prie D, Sedel F, Bernard D, Hercend C, Chanson P, Souberbielle JC. High-dose biotin therapy leading to false biochemical endocrine profiles: validation of a simple method to overcome biotin interference. Clin Chem Lab Med. 2017;55(6):817-825. PMID 28222020
- Odhaib SA, Mansour AA, Haddad NS. How Biotin Induces Misleading Results in Thyroid Bioassays: Case Series. Cureus. 2019;11(5):e4727. PMID 31363424
Stack Score
How this pair moves the number.
Effect on the composite score
If both Methimazole and Vitamin B7 are in the same stack, this pair applies −5 to your Stack Score (per scored caution row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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