Body composition and serum leptin level in Egyptian growth hormone deficient short children

ABSTRACT

Aim: This work was designed to evaluate the effect of growth hormone [GH]- deficiency on body composition and serum leptin level in Egyptian GH-deficient [GHD] short children. In addition, the relationship between serum leptin level, gender and anthropometric variables was also determined. Subjects and This study was conducted on 28 GHD children [19 boys and 9 girts] and 12 healthy controls [6 boys and 6 girls]. All children were prepubertal. Except for GH deficiency, the children were otherwise healthy with no evidence of organic diseases, chromosomal abnormalities, skeletal dysplasia or any other endocrinological disturbances. In all studied subjects, anthropometric parameters [weight, height, body mass index [BMI], waist/hip ratio [WHR] and subcutaneous skinfold thickness] were measured. To determine body composition, body fat percent [BF%] was calculated from subcutaneous skinfold thickness by specific equations from which the amount of total body fat mass [FM] and fat free mass [FFM] were calculated. Serum GH levels were estimated, using IRMA, under basal conditions and after applying two provocation tests [after exercise and after clonidine stimulation]. GH peak and GH area under the curve [GH AUC] were determined following clonidine stimulation. Baseline values of insulin-like growth factor-l [IGF-I] and leptin were also estimated in serum samples by ELISA. FFM was significantly lower in GHD children than controls. GHD children had a significantly higher BF% as compared to controls. Although FM showed a tendency to be higher in the GHD than the control group, the difference was statistically insignificant. Serum leptin level and leptin values, expressed per unit fat mass [ng/ml/kg], were significantly higher in GHD cases compared with controls. Significant positive correlations were detected between serum leptin and indices of adiposity [BMI, WHR, BF% and FM] in cases and controls. Multiple linear regression analysis with serum leptin considered as the dependent variable revealed that 52.6% of the variability of serum leptin level in GHD cases was significantly attributed to BF%,GH peak, GH AUC and IGF-I level [F= 8.480*, P= 0.000]. Healthy and GHD girls had a significantly higher BF%, FM and serum leptin levels than the boys of the corresponding group. However, leptin levels adjusted for fat mass did not differ significantly between boys and girls in each group. Conclusions: GH deficiency resulted in a significant increase of BF%. Serum leptin and leptin per unit fat mass were significantly higher in GHD cases. These findings suggest that GH could have an additional direct effect on leptin production from adipose tissue independent of its influence on body composition. Gender difference in serum leptin level is not obvious before puberty when the total body fat mass is taken into consideration