LEPTIN LEVELS ARE STRONGLY CORRELATED WITH THOSE OF GH-BINDING PROTEIN IN PREPUBERTAL CHILDREN

Objective: Nutritional status is an important determinant of growth, a nd previous studies have indicated that this is due, at least in part, to an increased target-tissue sensitivity to GI-I, An attractive cand idate for mediating this effect is leptin, a hormone secreted by the a dipose tissue. The aim of this study was to investigate if there was a connection between GH-binding protein (GHBP) and leptin. Design nod M ethods: We investigated the relationship between serum levels of lepti n and those of GHBP in 229 prepubertal children. These included 107 he althy children with normal GH secretion, 55 GH-deficient (GHD) childre n and 55 children born small for gestational age (SGA) sampled on one occasion for GHBP and leptin, and 12 healthy children followed longitu dinally at monthly intervals for 1 year. Results: In the healthy child ren and in those born SGA, the serum concentration of GHBP was positiv ely correlated with that of leptin (r = 0.65, P < 0.001; r = 0.74, P < 0.001 respectively), There was no correlation between GHBP and leptin in the group of children with GHD (r = 0.27, not significant), This m eans that leptin alone explained 42% of the variation of GHBP in the h ealthy group and 55% in the SGA group. The correlation remained after adjustment for body mass index and age in the healthy children (r = 0. 57, P < 0.0001, r(2) = 0.33) and for children born SGA Ir = 0.74, P < 0.0001, r(2) = 0.55). There was a positive correlation between the int ra-individual monthly changes in GHBP and changes in leptin respective ly in the 12 healthy children followed longitudinally, the mean of the correlation coefficients was 0.38 (median = 0.29; range 0.03 to 0.86; P < 0.05). Conclusions: There was a highly significant correlation be tween serum levels of leptin and those of GHBP, except in children wit h GHD. The possibility that leptin could mediate the effects of body f at mass on GH sensitivity therefore, merits further investigation.