[Endocrine constellation in androgenetic alopecia in the female]

The mechanisms which induce androgenetic alopecia in females are only poorly understood at the molecular biological level. In predisposed, mainly centroparietal areas, androgenic stimulation of genetically predisposed hair follicles is considered to cause transformation from terminal to vellus hair follicles. However, reports on serum androgen levels in androgenetic alopecia in the female show broad variations. In the present study serum androgens, gonadotropins, oestradiol and sex hormone binding globulin were determined in the luteal phase of the menstrual cycle in 25 patients with female pattern androgenetic alopecia by radioimmunosorbent assay. In 16 of these patients skin slices from the alopecic areas were punch biopsied under local anaesthesia for determination of cytosol- and nuclear androgen receptor (AR). Mean values of all serum hormone levels were within the normal range. Cytoplasmatic AR was positive in 75% of cases, with a mean level of 22 fmol/mg protein. In 50% of cases nuclear AR was demonstrated, with a mean level of 119 fmol/mg DNA. No correlation was found between serum androgen levels and AR. Highly positive AR levels indicate a high androgen stimulability in female androgenetic alopecia. These findings support the concept of AR as regulators of genetically determined hair follicles in androgenetic alopecia.