A supplement, not the thyroid, explained one patient's results
The results were markedly abnormal and did not match how the patient looked. After biotin was stopped they normalised far faster than thyroxine's half-life allows.
What the study found
A biotin user's thyroid results mimicked Graves disease
The results were markedly abnormal and did not match how the patient looked. After biotin was stopped they normalised far faster than thyroxine's own half-life allows, which is what identified them as an artefact of the test rather than thyroid disease. Other results were off too.
The caveat · One case, biotin never measured
A single case, paired with a review of other single cases: this shows that something can happen, never how often. The interference was inferred from how fast the results normalised rather than by measuring biotin in the sample. Assay formulations from 2016 have since been revised for biotin tolerance, and this patient's own dose is not a market-typical exposure.