Plasma leptin levels of large for gestational age and small for gestational age infants

The hormone leptin produced in the adipose tissue is involved in the regula tion of body weight. This study investigates whether plasma leptin levels a re related to an infant's birthweight, and whether the levels change with f eeding. We measured plasma leptin levels from infants who were large for ge stational age (n = 21), small for gestational age (n = 21), and appropriate for gestational age (n = 20). Two blood samples were collected before and after breastfeeding from each infant and plasma leptin concentrations were determined by radioimmunoassay. Leptin concentration was found to be increa sed in large for gestational age infants and to be decreased in small for g estational age infants compared with the level in appropriate for gestation al age infants. There was a positive correlation between plasma leptin leve ls and both the infants' birthweights and the body mass indexes. Plasma lep tin concentrations were found to be decreased during fasting and to be incr eased after feeding (p < 0.01). It is concluded that the plasma leptin leve ls correlate with the size of adipose tissue mass and are related to the nu tritional status.