Premature thelarche: a possible adrenal disorder.

Endocrine studies in girls with precocious thelarche were compared with those of normal girls of similar ages. Girls with precocious thelarche showed breast development and oestrogenised vaginal smears as the only signs of precocious sexual development. A few of the girls were tall and some had advanced bone ages but these two findings were not consistently present in the same patient. Hormones--such as serum oestradiol, oestrone, delta 4-androstenedione, progesterone, dehydroepiandrosterone (DHEA), follicle-stimulating hormone, luteinising hormone, and prolactin, and urinary 17-ketosteroids--were measured. Only DHEA was different, being higher in girls with precocious thelarche. It is suggested that the high DHEA level may serve as a precursor for conversion to oestrogens in target tissues, breast, and vagina. This mechanism for oestrogenisation had been reported in other patients.