Central precocious puberty: clinical and laboratory features.

OBJECTIVE: To determine whether the initial presentation of patients with central precocious puberty (CPP) varies according to the aetiology, whether this permits the differentiation between idiopathic and organic forms, and whether the body mass index (BMI) and plasma leptin concentrations are linked to gonadotrophin secretion.

DESIGN: The clinical and laboratory features of 256 patients (26 boys and 230 girls) with CPP were studied separately in boys and girls. We compared patients with idiopathic CPP (seven boys and 186 girls) to those with organic CPP, whose pubertal development revealed a central nervous system (CNS) lesion (five boys and 11 girls), and to patients with organic CPP associated with a previously treated CNS lesion (14 boys and 33 girls).

RESULTS: Boys with organic CPP, having revealed or treated CNS lesions, started their puberty earlier (3.0 +/- 1.0 years and 6.7 +/- 0.5 years) than boys with idiopathic CPP (8.5 +/- 0.2 years, P < 0.01 and < 0.05). Boys with organic CPP associated with a treated CNS lesion had lower luteinizing hormone (LH)/follicle stimulating hormone (FSH) peaks ratio after stimulation with gonadotrophin releasing hormone (GnRH) (1.6 +/- 0.5) than did boys with idiopathic CPP (2.2 +/- 0.3, P < 0.05). Girls with organic CPP revealing a CNS lesion started their puberty earlier (3.6 +/- 0.9 years) than girls with idiopathic CPP (6.6 +/- 0.1 years, P < 0.0 l) and had higher LH (P < 0.01) and FSH peaks (< 0.05). Girls with organic CPP associated with a treated CNS lesion had higher BMI (1.8 +/- 0.2 z-score) than did girls with idiopathic CPP (1.3 +/- 0.1 zs, P < 0.05), higher leptin concentrations (11.7 +/- 1.8 microg/l vs. 7.7 +/- 0.5 microg/l, P < 0.0 l), LH peak (P < 0.01), FSH peak (P < 0.05) and LH/FSH peaks ratio (1 +/- 0.1 vs. 0.8 +/- 0.1, P < 0.05). Only 12.4% of the girls with idiopathic CPP had BMI-zs < 0, and their plasma leptins were positively correlated with BMI (P < 0.0001).

CONCLUSIONS: The features of central precocious puberty vary according to the aetiology, but it is impossible to exclude a central nervous system lesion in a given patient with central precocious puberty without performing central nervous system imaging. This imaging remains necessary in all cases of central precocious puberty. Most of the girls with idiopathic central precocious puberty had increased BMI, but we found no correlation between plasma leptin concentrations and gonadotrophin secretion.