Background: In recent years, an increasing number of infants have been seen with fine hair in the genital area and no other signs of androgen excess, but the hormonal basis of this finding is unknown.
Aim: To compare steroid profiles in infants with genital hair with age-matched control infants, using liquid chromatography-tandem mass spectrometry (LC-TMS) to measure eight steroids (cortisol, 11-deoxycortisol, progesterone, 17-hydroxyprogesterone, testosterone, androstenedione, DHEA, and DHEA-S).
Patients: Samples were obtained between 1/04 and 12/05 from infants with genital hair, and for comparison, a group of 5-9 year-olds with premature adrenarche, as well as control children of similar ages being seen for thyroid problems or short stature.
Results: Steroid profiles in infants with genital hair were similar to those in control infants, except that DHEA-S levels were somewhat higher (17.5 vs. 7.6 microg/dl [476 vs. 207 nmol/l]; p = 0.067), and six of 12 had levels >15 microg/dl (408 nmol/l) vs. one of 12 controls. Testosterone levels were low (<10 ng/dl [<350 pmol/l) in nearly all infants with pubic hair; the main exception was a girl whose father used topical testosterone (31 ng/dl [1076 pmol/l]). Genital hair disappeared in two patients over time but persisted for 6 months to 2 years in most.
Conclusions: No pathological increase in steroid levels was found in infants with genital hair vs controls, though a mild elevation of DHEA-S was seen in about half. This suggests that pubic hair in infancy may represent a mild and early onset variant of premature adrenarche, with a benign clinical course.