TLDR Thyroid hormone (T3) may reverse gray hair by stimulating hair growth.
The study investigated the effects of thyroid hormone (T3) on hair follicles, particularly its potential to reverse graying. Two patients experienced darkening of gray hair after increased T3 levels due to medical conditions. Using a murine model, T3 was applied topically, resulting in all treated mice entering the anagen phase by day 5, compared to day 9 in controls. In vitro, follicular units treated with T3 showed significant growth. These findings suggested that T3 could stimulate hair follicles in the telogen phase to enter anagen and potentially reverse hair graying, with follicular melanocytes as the likely target cells.
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Thyroid problems can cause hair loss and change hair texture.
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