Diffuse Hair Loss And Clinical Endocrinology: New Insights

Diffuse hair loss was a common condition that posed diagnostic challenges. Over the past decade, significant progress was made in understanding the hormonal effects on hair follicles. Corticotropin-releasing hormone (CRH) was expressed in murine hair follicles, peaking during the anagen phase, and stress-induced CRH could lead to increased hair loss. Melatonin, also expressed in hair follicles, influenced hair cycle processes and androgen/estrogen signaling pathways, with topical application increasing anagen hairs. Leptin promoted hair growth and skin regeneration by activating STAT3, inducing the anagen phase in mice. A large Korean study found a positive association between androgenetic alopecia and metabolic syndrome in women, but not in men. Prolactin accelerated the transition to the catagen phase, reducing keratinocyte proliferation and increasing apoptosis, with hyperprolactinemia-induced hair loss linked to certain medications. The Vitamin-D receptor (VDR) was closely associated with hair growth, controlling the hair cycle independently of its ligands. Data on iron levels and hair loss were inconsistent, with a ferritin level of 40 μg/l potentially linked to increased hair loss, though the effect of iron supplementation on hair regrowth remained unclear. Various hormones influenced hair growth through endocrine, autocrine, or paracrine pathways, and new studies provided insights into the complex regulatory mechanisms and potential future therapies.