Thyroid Hormone Action on Skin

The 2012 document reviews the role of thyroid hormone in skin physiology and its potential as a treatment for skin diseases. It discusses the historical skin symptoms associated with thyroid disorders, the presence of thyroid hormone receptors in skin cells, and the conversion of T4 to T3 in the skin. The review also examines the effects of thyroid hormone on skin cell proliferation, epidermal and dermal changes, hair and nail growth, and autoimmune skin manifestations related to thyroid dysfunction. While in vitro studies show thyroid hormone stimulates skin cell proliferation, the in vivo effects are still debated. The document also reports that topical thyroid hormone and analogs can promote skin and hair growth in animals, and that high doses of T3 can speed up wound healing in rodents, with a potential formulation for human wound healing including T4. However, the impact on human wound healing is unclear, with mixed study results. The conclusion suggests that thyroid hormone pathways are significant for skin health and could be targeted for treating skin diseases, but more research is needed to fully understand the effects.