Occasionally after a diagnostic evaluation for hirsutism, there is no explanation for the cause of the disorder. By exclusion, this condition is often called constitutional hir-sutism. Data support the hypothesis that women with con-stitutional hirsutism have greater activity of 5α-reductase than do unaffected women.
Treatment of constitutional hirsutism is primarily androgen blockade and mechanical removal of the excess hair. Spironolactone 100 mg/day is the most commonly used androgen blocker. Spironolactone also inhibits testos-terone production by the ovary and reduces 5α-reductase activity. Other androgen blockers include flutamide and cyproterone acetate. The activity of 5α-reductase can also be inhibited directly through the use of drugs such as finas-teride (5 mg orally daily). Eflornithine hydrochloride 13.9% is an irreversible inhibitor of L-ornithine decarboxy-lase, which slows and shrinks hair. This cream has been approved for facial use with satisfactory local effects. Patients taking an androgen receptor or 5α-reductase blocker should be placed on concomitant oral contracep-tives because of the teratogenic and demasculinizing effects on a fetus should pregnancy occur. Oral contraceptives may also improve the efficacy of these treatments through the decreased androgen and increased SHBG production effects associated with their use.