Elevated ghrelin levels in preterm born children during prepubertal ages and relationship with catch-up growth

Abstract

BACKGROUND: Ghrelin, the natural ligand of the GH secretagogue receptor, has potent orexigenic effect. Ghrelin levels are negatively associated with insulin secretion, increased in anorexia, and reduced in obesity. Increased ghrelin levels may be associated with early postnatal growth in preterm born children. OBJECTIVE: Aim of this study was to evaluate ghrelin and insulin levels at prepubertal ages in preterm born children born appropriate for gestational age (AGA) or small for gestational age (SGA) and relationships with catch-up growth (CUG) in a prospective cross-sectional study. METHODS: Eighty-four preterm born children grouped as preterm SGA (n=28) and preterm AGA (n=56) were evaluated at age 4.7+/-0.2 and 4.7+/-0.1 years with respect to their ghrelin and insulin levels. Their data were compared with that of body mass index matched term SGA (n=35) and term AGA (n=44) children of age 4.6+/-0.2 and 3.8+/-0.1 years. All children had height appropriate for their target height. CUG was defined as the difference between birth size and recent size and expressed as Delta height and Delta weight SDS. RESULTS: Preterm SGA and preterm AGA children had similar ghrelin levels (1717.0+/-166.9 and 1656.5+/-103.8 pg/ml), although Delta height and Delta weight SDS in preterm SGA were significantly higher than in preterm AGA children (P<0.001). Ghrelin levels in both preterm groups were higher than term SGA (469.2+/-132.5 pg/ml) and term AGA children (659.6+/-143.3 pg/ml; P<0.001 for all). Delta Height and Delta weight SDS of the term SGA children were similar to that of preterm SGA children. Ghrelin did not have correlation with CUG but had inverse correlation with recent anthropometric indices. Insulin was significantly higher in term SGA children than other groups (P<0.001). CONCLUSIONS: Preterm children have higher ghrelin levels at prepubertal ages regardless of the magnitude of their CUG. Term SGA children, on the other hand, behave differently and have lower ghrelin levels than preterm children at prepubertal ages, which may be related to elevated insulin levels in this group.