The Effect of Parathyroid Hormones on Hair Follicle Physiology: Implications for Treatment of Chemotherapy-Induced Alopecia

The 2015 document reviews the potential of parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) as therapeutic targets for chemotherapy-induced alopecia (CIA). It explains that PTH and PTHrP are involved in hair follicle cell proliferation and differentiation, with their receptor signaling being crucial for the hair cycle. Studies on mice have shown that overexpression or blockade of PTHrP can impair or increase hair growth, respectively. Furthermore, PTHrP may also inhibit angiogenesis, which is important for hair cycling. Antagonists of the PTH/PTHrP receptor have been found to stimulate hair follicle cell proliferation and hair growth, and topical application of these antagonists has promoted hair growth in hairless mice and mice treated with chemotherapy. Despite these findings, clinical trials using topically administered PTH(7–34) in CIA were unsuccessful. The document concludes that while PTH/PTHrP and their receptors are important in hair biology, their practical application in treating hair loss disorders is still uncertain.