Extrathyroidal effect of thyroid hormones

Hypothyroid patients receiving thyroxine (T4) monotherapy have a higher plasma T4/T3 ratio due to the lack of T3 secretion by the thyroid. Many studies have concluded that there is no benefit to combined T4/T3 therapy over T4 monotherapy. However, Schmidt and colleagues recently demonstrated that combination therapy is superior in several parameters; this study extends these finding to show that several peripheral tissues register different T3 availability during T4/T3 combination substitution in hypothyroid subjects. Both hepatic function and collagen production during bone formation seem to be stimulated. This study encourages the development of prolonged T3 formulations for further clinical study.

Read the full article in Schmidt and colleagues (2013) Endocrine Connections 2 55—60 DOI: 10.1530/EC-12-0064