Therapeutic Potential of two Over-The-Counter Thyroid Hormone Preparations

Abstract

Various brands of over-the counter (OTC) exogenous thyroid hormones are available in health food stores and retail pharmacies. Two commercially available OTC thyroid products were analyzed for total thyroxine (T₄) and triiodothyronine (T₃) content. The strength of a liquid thyroid gland extract was unlabeled and that of the solid oral preparation was 45 mg per tablet. The T₄ concentration of the liquid preparation was <10 μg/dL; that of T₃ was below the analytical sensitivity of our assay (<15 ng/dL). Tablet content of T₄ and of T₃ was up to 0.5 μg and up to 50 ng, respectively. Preliminary data on these OTC thyroid gland extracts cannot be extrapolated to all OTC thyroid products, but they suggest that such products generally contain concentrations of T₄ and T₃ below clinical effectiveness. Further analytical study is warranted.