Serum leptin levels in preterm, healthy and sick-term newborns

Leptin, a hormone that signals the brain about the status of body (fat) energy stores, has recently been shown to play a role in the regulation of several hypothalamic pituitary axes, including the growth hormone axis. To investigate a potential association of serum leptin concentrations and clinical condition in preterm, sick term and healthy term newborns, serum leptin concentrations were evaluated in 104 newborns. Twenty-eight of them were healthy term (18 males and 10 females; gestational age, 37-42 weeks), 21 were sick term (12 males and 9 females; gestational age, 37-42 weeks) and 55 were preterm neonates (35 males and 20 females; gestational age: 26-37 weeks). Leptin values correlate positively with birth weight, birth length, head circumference, waist circumference, hip circumference, body surface, weight/length ratio, and gestational age (r = 0.38, 0.42, 0.29, 0.21, 0.29, 0.40, 0.31 and 0.28), respectively. The concentrations of leptin are statistically significantly higher (p < 0.05) in term neonates (3.02 +/- 2.94 ng/ml) than preterm neonates (1.93 +/- 2.21 ng/ml). Female infants also have significantly higher (p < 0.05) serum leptin values than male infants in preterm and healthy term groups. We also found leptin present in venous blood after 26 weeks of gestation.