Hypothalamo-pituitary-gonadal function in male central precocious puberty.

Eleven boys aged 1-10 years with central precocious puberty were studied. According to the pubertal development six were classified as P2, one as P3 and four as P5. In all cases plasma testosterone levels were definitely elevated (1.7-5.8 ng/ml) when compared with pre-pubertal controls. Peak values after HCG (3 X 1500 units) in four of the boys were in the high adult range. The binding capacity of serum testosterone oestradiol binding globuline (TeBG) ranged between 0.5 and 7.30 microgram/dl. Basal plasma levels of LH and FSH were respectively 2.06 +/- 0.64 and 1.2 +/- 0.25 miu/ml, and peak levels after LHRH (0.1 mg/m2) 13.9 +/- 3.7 and 2.6 +/- 0.43 miu/ml respectively. The data demonstrated a significant increase of plasma testosterone and post LHRH LH peak levels in boys with central precocious puberty when compared with pre-pubertal controls. The patients at stage P2 exhibited high levels of plasma testosterone contrasting with the degree of pubertal maturation, high values of TeBG and low response to LHRH which were in the pre-pubertal range. These findings suggest that the testicular sensitivity to LH increases early in boys with central precocious puberty, while the testosterone responsiveness, both at peripheral and hypothalamic levels, is delayed.