2 DIFFERENT PATHOGENETIC MECHANISMS MAY PLAY A ROLE IN ACNE AND IN HIRSUTISM

OBJECTIVE Acne is one of the most common skin disorders. Androgens are known to play an important and possibly central role. Androgens secre ted from ovaries and adrenal glands (androstenedione, dehydroepiandros terone and its sulphate, testosterone) and target tissue-produced andr ogens (testosterone and its 5alpha-reduced metabolite, dihydrotestoste rone) have been implicated. Although the sebaceous gland and the hair follicle form a single morphological entity, the pilosebaceous unit, a cne and hirsutism do not always appear concomitantly, thus leading to the supposition that these two structures may have different degrees o f sensitivity to similar androgenic stimulation. DESIGN AND PATIENTs T o determine whether acne and hirsutism are the clinical expression of a different androgen metabolism at target tissue levels we studied 90 randomly selected patients who came to our Out-patient Department for diagnosis and treatment during the last 2 years with isolated acne of mild to severe degree and 52 patients with idiopathic hirsutism withou t acne or history of acne. Twenty-four women without acne or hirsutism and without a history of endocrine disease were studied as controls. MEASUREMENTS in both groups of patients, plasma levels of sex hormone binding globulin, of dihydrotestosterone, and of 3alpha-androstanediol and of its glucuronide were evaluated. In all patients the percentage of free testosterone and the testosterone/sex hormone binding globuli n ratio were also calculated. RESULTS Patients with acne and those wit h isolated hirsutism showed significantly decreased sex hormone bindin g globulin plasma levels. The values of the percentage free testostero ne and those of the testosterone/sex hormone binding globulin ratio we re, on the contrary, higher with respect to the controls, although the re were no statistically significant differences between the two group s. Significantly increased plasma levels of dihydrotestosterone with r espect to the controls were observed in patients with acne or in those with hirsutism. However, while all patients with hirsutism showed inc reased plasma values of 3alpha-androstanediol and its glucuronide, all patients with acne showed plasma levels within the normal range, inde pendently of the precursor plasma levels. CONCLUSIONS Our results demo nstrate that dihydrotestosterone is further reduced to 3alpha-androsta nediol and its glucuronide only in hirsute patients but not in acne pa tients. These results suggest that dihydrotestosterone may undergo dif ferent metabolic pathways at skin levels and support the hypothesis th at the two clinical manifestations may be the expression of the differ ent metabolic fate of dihydrotesterone itself. Moreover, our results d emonstrate that 3alpha-androstanediol and its glucuronide cannot be us ed as plasma markers of target-tissue produced androgens in all hypera ndrogenic conditions.