Serum adiponectin in newborns and in one and two years old infants: relationship with body weight, leptin and insulin

ABSTRACT

Adiponectin is the only adipose-specific hormone that, despite its exclusive production by adipose tissue, is reduced in obesity and is inversely correlated with leptin levels in adults. It plays a critical role in the control of energy balance in adult life. However, its functions and relations to other hormones are not yet fully understood in infants. The aim of this study is to assess adiponectin levels in newborns at birth, one and two years of life and to define its association with weight, serum leptin and insulin. Serum adiponectin, leptin and insulin levels were investigated in 48 newborns [24 small for gestational age [SGA] and 24 appropriate for gestational age [A GA]]. Infants aged one year [n=20] and two years [n=20] were also included in this study. The levels of serum adiponectin were significantly decreasing while serum leptin and insulin were significantly increasing at one and two years. Serum adiponectin was correlated positively with weight [r=0.509, p<0.001] and leptin [r=0.355, p<0.05] but not correlated with serum insulin in all newborns. At one and two years adiponectin was correlated positively with insulin [r=0.444, p<0.05 and r0.448, p<0.05 respectively]. The correlation between adiponectin and weight at one year [r=-0.056, p=0.816] and between it and leptin at two years [r=-0.171, p=0.471] changed into negative but did not reach a statistically significant level. Serum leptin was correlated positively with weight in all newborns [r=0.935, p<0.001]. At two years it was positively correlated with weight [r=0. 721, p<0.001] and insulin [r=0.641, p<0.01]. Serum adiponectin and leptin levels were significantly lower in SGA than AGA infants [30.08 +/- 9.54 micro/ml and 4.33 +/- 3.20 microg/L, p<0.001 respectively] but there was no difference in serum insulin. In conclusion, adiponectin is higher in newborns than at one and two years. The change in correlation of adiponectin with weight and leptin from positive in newborns to negative in adults might occur at the first 2 years of life