Mechanisms of thyroid hormone action. Implications for the clinical manifestation of thyrotoxicosis.

Serum thyroid hormone concentrations alone do not explain the variability and severity of the range of symptoms observed in thyrotoxic patients. Despite gaps in our understanding of the links between the clinical manifestations of thyrotoxicosis and the underlying mechanisms, much has been learned. A limited number of markers directly reflect T3 action. The future elucidation of T3 targets that mediate these effects should ultimately lead to additional clinical markers of tissue-specific T3 action. The availability of such tests should allow for more specific treatment of individual patients.