Acylated/unacylated ghrelin ratio in cord blood: correlation with anthropometric and metabolic parameters and pediatric lifespan comparison

Context: Ghrelin is a peptide with multiple functions that circulates in acylated (AG) and unacylated (UAG) forms. However, the role of ghrelin in neonates (NN) remains to be clarified. Objective: The aim of this study was to determine ghrelin concentrations of the two forms in NN to clarify their biological roles. As such, ghrelin levels at birth were compared with those in later life. Setting and design: Tertiary Care Center. In this cross-sectional study, we evaluated AG, UAG, AG/UAG ratio, and insulin levels in venous cord blood from NN and in fasted normal weight (NW) and obese (OB) children, both prepubertal and pubertal. Subjects: We studied 82 NN, 82 NW, and 58 OB children. Results: AG levels were lower in NN than in NW and OB children (P<0.0001), more specifically the prepubertal NW and OB children (P<0.0001). UAG levels were higher in NN than in NW and OB children (P<0.0001). Therefore, the AG/UAG ratio was lower in NN than in NW and OB children (P<0.0001). NN showed insulin levels similar to NW and lower than OB children (P<0.0001). At birth UAG was positively correlated with AG (Pearson: 0.425; P<0.0001) and negatively with insulin (-0.253; P<0.02). In NW and OB, UAG and AG were positively correlated to each other and negatively correlated with insulin and body mass index (-0.566; P<0.0001). Conclusions: NN compared with children, showed higher UAG and lower AG levels. The AG/UAG ratio showed a very different profile in NN, being lower than in NW and OB children, thus suggesting a different metabolic function for the two forms in NN. Further studies are needed to clarify the exact role of the different ghrelin forms in NN.