Isosexual precocity: the clinical and etiologic profile.

Eighty children (58 girls and 22 boys) with isosexual precocity seen in the past eight years were evaluated clinically and investigated to identify the underlying cause. Of these, 50% (29 girls and 11 boys) had centrally mediated true precocious puberty (TPP). The girls could be classified into five major groups (I) Central precocious puberty 29-subclassified into idiopathic (ITPP, 15) and organic or neurogenic (NTTP, 14), (II) Premature thelarche (PT, 20), (III) Premature menarche (PM, 2), (IV) Premature adrenarche (PA, 5), and, (V) Others: hypothyroid (n = 1), and McCune Albright Syndrome (n = 1). ITPP as a cause of precocity in girls was seen less often (52%) and NTPP more often (48%) compared to most Western series, with tubercular meningitis as the cause in 31% and hypothalamic hamartomas in 10%. Though the LH and estradiol levels were significantly higher (p < 0.05) in TPP, compared to PT, these were not helpful in differentiating because of considerable overlap. LH-predominant-response (LH/FSH ratio > 1) to LHRH testing was seen in TPP. Amongst the 22 boys, 11 (50%) had TPP, ITPP in 27% and NTPP in 73%. Hamartomas (n = 4) and TBM (n = 3) contributed equally to NTPP; pineal tumor was seen in one. The adrenal (n = 7) and testicular (n = 2) causes together involved 41% of the boys with precocity, congenital adrenal hyperplasia (CAH) CAH, 11-beta hydroxylase being the commonest cause. Of the 6 boys witdeficiency was found in four and nonsalt losing form of 21-hydroxylase deficiency in 2. Testicular and adrenal tumors and testotoxicosis were noted in one case each. The etiologic factors were more varied in boys.