OBJECTIVESTo study the roles of leptin in the development during puberty in girls and the its relationship with insulin (INS), growth hormone (GH), estradiol (E(2)) and testosterone (T).

METHODSOne hundred and fifty girls with simple obese aged 7 to 17 years, and 150 normal healthy girls and 150 girls with malnutrition matched for age (+/- 3 months) and height (+/- 2 cm) were selected. Serum levels of leptin, INS, GH, E(2) and T were measured for them.

RESULTSTheir serum level of leptin positively correlated with body mass index (BMI) and age. Serum level of leptin in girls increased steadily from Tanner stage B(1) to stage B(5). At Tanner stage B(2), serum level of leptin in the normal groups (7.72 microg/L) was not significantly different from that in those with malnutrition (7.36 microg/L), but significantly lower than that in the obese groups (12.85 microg/L). At other Tanner stages, there was significant difference in serum level of leptin among obese, normal and malnutrition groups. Serum level of leptin correlated negatively with serum GH and positively with serum INS, but not correlated with E(2) and T.

CONCLUSIONSLeptin may play a role in triggering development during puberty in girls. Serum level of leptin at Tanner stage B(2) may be the threshold dose to trigger the onset of puberty in girls. Quickly increasing level of leptin at Tanner stage B(5) may inhibit the increase of GH, which ushered the end of puberty in girls.