[Insulin receptors in intrauterine growth retardation].

This report analyses erythrocyte insulin binding and specific erythrocyte insulin receptors in the neonatal period. Authors have studied thirty normal newborns who had an adequate weight for their gestational age and another fifteen who were asymmetric intrauterine retarded growth. Cord blood samples were collected and insulin binding, insulin receptors, blood glucose concentration, serum immunoreactive insulin, serum C-peptide concentration and molar ratio of C-peptide to insulin were determined. Insulin and C-peptide sera concentrations suggest that basal insulin secretion in small for data newborns is similar to term infants. Significantly minor affinity constant (p = 0.05) and significantly major dissociation constant (p = 0.05) in small for date infants versus newborns adequately weighted for their gestational age, justify the increased sensitivity to insulin as it happens in other states of chronic undernutrition. In small for date infants, number of sites per cell correlates negatively (r = -0.57, p less than 0.05) with birth weight. Up regulation mechanism that modulates receptors concentration could explain this phenomenon.