Determination of thyroid hormones in dietary supplements using liquid chromatography-tandem mass spectrometry.
Level 5 - mechanism / opinion, no new human data
Analytical laboratory assay of commercial products (bench research with no clinical trial or human subject data)
PubMed 33855795 · doi:10.1002/dta.3046
What was done
Researchers developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay to quantify five thyroid hormones and metabolites: thyroxine (T4), 3,3',5-triiodo-l-thyronine (T3), reverse T3 (rT3), 3,5-diiodothyronine (3,5-T2), and 3,3'-diiodothyronine (3,3'-T2). Extraction used methanol sonication for nonglandular products and a combined methanol sonication plus protease enzymatic digestion for tissue-bound hormones in glandular products. The method was applied to analyze 58 dietary supplements with thyroid management claims purchased online between 2017 and 2018.
What was found
The extraction method demonstrated recovery rates between 78% and 116%. Out of 19 glandular products tested, 11 contained quantifiable amounts of thyroid hormones. Based on maximum recommended daily servings on product labels, glandular products contained up to 210 µg/day of T4, 32 µg/day of T3, and 7.6 µg/day of rT3. In nonglandular products, 3,5-T2 was detected at levels up to 740 µg/day, and 3,3'-T2 was detected at levels up to 2700 µg/day.
Why it matters
Over-the-counter supplements marketed for thyroid support can deliver physiologically potent doses of active thyroid hormones that exceed typical therapeutic replacement doses, creating a serious risk of supplement-induced thyrotoxicosis or drug interactions.
Limits
The study evaluated a sample of 58 products purchased online from 2017 to 2018, which may not represent all retail brands or current formulations. The abstract reports no longitudinal data, batch-to-batch variation assessments, or direct clinical measurements of patient exposure or adverse events.
Cited by
- supports Natural desiccated thyroid formulations contain a blend of T4, T3, and T2.