The relationship between decreased iron stores, serum iron and neonatal hypoglycemia in large-for-date newborn infants

We assessed the relationship between neonatal hypoglycemia and newborn iron status in 15 hypoglycemic, large-for-date newborn infants, 12 of whom were infants of diabetic mothers. These infants had significantly lower mean serum iron concentrations, ferritin concentrations, percent iron-binding saturation and calculated iron stores, and significantly higher mean transferrin concentrations, total iron-binding capacity concentrations and mid-arm circumference:head circumference ratios when compared with either 15 euglycemic large-for-date or 15 euglycemic appropriate-for-date control infants (p less than 0.001 for all comparisons). All hypoglycemic infants had ferritin concentrations below the 5th percentile as compared to 3% of controls (p less than 0.001), and 67% had transferrin concentrations above the 95th percentile (controls: 0%; p less than 0.001). Only the hypoglycemic infants demonstrated a significant negative linear correlation between ferritin and transferrin concentrations (r = -0.83; p less than 0.001). Decreased serum iron concentrations were associated with size at birth (r = -0.60; p = 0.01) and with increased red cell iron (r = -0.60; p = 0.01), implying a redistribution of iron dependent on the degree of fetal hyperglycemia and hyperinsulinemia. Infants with increased red cell iron had more profound neonatal hypoglycemia. These results show a significant association between decreased iron stores and neonatal hypoglycemia in macrosomic newborn infants associated with a significant shift of iron into red blood cells.