Pubic hair in boys due to adrenarche rather than true puberty

Abstract

Pubic hair sometimes develops in boys before testicular enlargement. We have tested the possibility that this situation can be due to adrenarche rather than true puberty. Eight cases between 5.5 and 12.8 years of age were observed to have stage III pubic hair and prepubertal-size testes. All were healthy; 5 were obese. Plasma dehydroepiandrosterone sulphate (DHAS) levels were 94-228 μg/dl, above the 95% limits for age. Plasma testosterone at 0800-1300 hr was 11-28 ng/dl. Bone age was normal or only slightly advanced. Diurnal blood sampling and ACTH testing were carried out in an 8.6 year old case. Daytime and nighttime testosterone were similar (16-30 ng/dl), ruling out early true sexual precocity. His baseline pattern and response of steroid intermediaries to ACTH was typical of premature adrenarche, ruling out adrenogenital syndrome. In two other cases the pattern of plasma steroid intermediates was normal and DHAS was shown to be normally dexamethasone-suppressible. These studies show that isolated onset of pubic hair in boys without testicular enlargement does not necessarily indicate true puberty or virilization, but is often due to adrenarche as a variation of normal. Furthermore, these results suggest an association between premature adrenarche and obesity.