ESPE Abstracts

Background: Leptin has a major role in the metabolic gating of pubertal maturation. Kisspeptin is an essential gatekeeper of puberty. Neurokinin B (NK B) is not widely known in the precocious puberty (PP) but it is coexpressed with kisspeptin in the arcuate nucleus and synchronizes the pulsatile secretion of kisspeptin.

Objective and hypotheses: Leptin, kisspeptin, and NK B are influenced by energy balance and metabolic status has a clear impact on the timing of puberty. Therefore, we aimed to investigate the relationships of circulating leptin, kisspeptin, and NK B levels with PP in overweight/obese girls and to evaluate the usefulness of these serum markers in the initiation of puberty.

Method: One hundred forty PP girls aged 6–9 years and 38 age-matched normal control (NC) girls were enrolled. PP girls were classified according to their body mass index (BMI) as follows: normal weight (NW), 5 percentile ≦ BMI z-score < 85 percentile; overweight/obese (OW/OB), 85 percentile ≦ BMI z-score. All NC girls were normal weight. Chart reviews were done for anthropometric data and biochemical results. Serum leptin, kisspeptin, and NK B levels were measured by ELISA or EIA kits.

Results: Median serum leptin levels were 2.2 ng/ml in NC girls, 3.8 ng/ml in NW PP girls, and 4.8 ng/ml in OW/OB PP girls and those differences were significant (P<0.001). Serum leptin levels had positive correlation with BMI z-score regardless of pubertal status (r=0.383, P<0.001). Serum kisspeptin levels of NW PP girls (0.57 ng/ml) were lower than OW/OB PP girls (0.64 ng/ml, P=0.039) but those were not differ from NC girls (0.57 ng/ml). Serum NK B levels were not different among three groups. Serum leptin, kisspeptin, and neurokinin B levels were not related to basal LH/FSH/estradiol and peak LH/FSH levels. Considering as a diagnostic marker, serum leptin levels had no priority than serum IGF-1 level (AUC of leptin=0.725; AUC of IGF-1=0.928; P=0.001).

Conclusion: Serum leptin levels showed significant correlation with PP and obesity as they are known so far, but it is hard to use commercially compared to conventional indices. Meaningless results of serum kisspeptin and NK B levels may be because their serum levels do not reflect their tissue concentations proportionately.