Serum leptin levels in premature pubarche and prepubertal girls with and without obesity

Leptin can be regarded as a marker of the nutritional status of the body. This study was performed to determine the correlation of leptin levels with insulin (I) and androgens in girls with premature pubarche (PP) and prepubertal controls (C) with (OB) or without (nOB) obesity. We studied 25 girls with PP and 14 C; girls were dived into two subgroups according to body mass index (BMI): OB (18 PP and 8 C) and nOB (7 PP and 6 C). Obesity was defined as BMI >95th percentile for chronological age. Serum levels of leptin, I, glucose (G), DHEAS, testosterone, androstenedione (A), cortisol, SHBG, IGFBP-1 and lipid profile were measured. The fasting G to I ratio (FGIR) was calculated and FGIR <7 was considered as suggestive of I resistance (IR). Data were analyzed comparing PP vs C and OB vs nOB. Serum DHEAS (0.60 +/- 0.45 vs 0.18 +/- 0.22 microg/ml) and A (895.5 +/- 420.4 vs 457.0 +/- 352.1 pg/ml) levels were significantly higher in PP than C. Other hormonal and metabolic parameters were similar. Serum leptin (30.8 +/- 18.3 vs 8.1 +/- 5.9 ng/ml), A (841.8 +/- 471.1 vs 522.5 +/- 317.2 pg/ml), DHEAS (0.53 +/- 0.44 vs 0.31 +/- 0.39 microg/ml), G (88.4 +/- 8.8 vs 80.2 +/- 8.1 mg/dl), I (13.5 +/- 7.7 vs 5.1 +/- 3.7 microU/ml) and total cholesterol (TC) (180.5 +/- 30.9 vs 161.8 +/- 29.5 mg/dl) levels were greater in the OB than in the nOB group. IR was observed in 10 girls with OB and in one with nOB. Leptin was correlated with BMI (r = 0.83), SHBG (r = -0.44), IGFBP-1 (r = -0.47), I (r = 0.37), A (r = 0.48) and TC (r = 0.36), but in multiple regression analysis only with BMI (r2 = 0.72, p < 0.001). Girls with PP and prepubertal OB girls showed elevated leptin levels independent of I and androgen levels. Girls with OB had a greater degree of hyperandrogenism and IR. As obesity, IR and hyperandrogenism are common findings in polycystic ovary syndrome (PCOS), which is more prevalent in young women with a history of PP, a role of leptin in PCOS can be suggested. In addition, girls with PP could be considered a population at risk for plurimetabolic syndrome.