Although the physiologic role of thyroid hormone in skin is not well understood, mounting evidence suggests that triiodothyronine (T₃) plays an important role in epidermal proliferation. The goal of this project was to evaluate whether the topical application of supra-physiologic doses of T₃ could accelerate wound healing.

We evaluated mice treated with topical T₃ vs. the same mice receiving vehicle alone (Novasome A). Ten mm diameter (79 mm²) dorsal skin wounds were established in all animals and wounds were re-measured 4 days following injury. All animals were evaluated twice: once with the T₃ treatment and once with the vehicle alone. Daily topical application of 150 ng T₃ resulted in 58% greater wound closure relative to wounds on the same animals receiving vehicle alone (P < 0.001). Further, we determined that wound healing associated keratin 6 protein expression in hair follicle keratinocytes increased in a dose dependent manner in vivo during topical T₃ treatment.

The data support our previous hypothesis that T₃ is necessary for optimal wound healing. Now, we further suggest that topical thyroid hormone may be an inexpensive agent to hasten healing of certain wounds.