Idiopathic hirsutism

Hirsutism, the presence of terminal (coarse) hairs in females in a male-lik e pattern, affects between 5% and 10% of women. Of the sex steroids, androg ens are the most important in determining the type and distribution of hair s over the human body. Under the influence of androgens hair follicles that are producing vellus-type hairs can be stimulated to begin producing termi nal hairs (i.e., terminalized). The activity of local 5 alpha-reductase (5 alpha-RA) determines to a great extent the production of dihydrotestosteron e (DHT), and consequently the effect of androgens on hair follicles. While there are two distinct 5 alpha-RA isoenzymes, type 1 and type 2, the activi ty of these in the facial or abdominal skin of hirsute women remains to be determined. Although the definition of idiopathic hirsutism (IH) has been a n evolving process, the diagnosis of IH should be applied only to hirsute p atients with normal ovulatory function and circulating androgen levels. A h istory of regular menses is not sufficient to exclude ovulatory dysfunction , since up to 40% of eumenorrheic hirsute women are anovulatory. The diagno sis of IH, when strictly defined, will include less than 20% of all hirsute women. The pathophysiology of IH is presumed to be a primary increase in s kin 5 alpha-RA activity, probably of both isoenzyme types, and possibly an alteration in androgen receptor function. Therapeutically these patients re spond to antiandrogen or 5 alpha-RA inhibitor therapy. Pharmacological supp ression of ovarian or adrenal androgen secretion may be of additional, albe it limited, benefit. New therapeutic strategies such as laser epilation or the use of new biological response modifiers may play an important role in offering a more effective means of treatment to remove unwanted hair. Furth er investigations into the genetic, molecular, and metabolic aspects of thi s disorder, including only well defined patients, are needed.