Plasma osmolality, sodium, and urea in healthy breast-fed and bottle-fed infants in Newcastle upon Tyne.

Dale, G., Goldfinch, M. E., Sibert, J. R., and Webb, J. K. G. (1975). Archives of Disease in childhood, 50, 731. Plasma osmolality, sodium, and urea in healthy breast-fed and bottle-fed infants in Newcastle upon Tyne. Plasma osmolality, sodium, and urea were measured on samples from 50 healthy infants, aged between 18 and 125 days, attending child health clinics in Newcastle upon Tyne. 3 infants had osmolalities greater than 300 mOsm/kg, a lower incidence of hyperosmolality than that previously reported. There was a difference (P less than 0-001) between the plasma urea levels of breast-fed and bottle-fed infants, but not between the osmolalities of these groups. The mean plasma urea of bottle-fed babies was 53 mg/100 ml (SD 12-47), 50-1 mg/100 ml (SD 10-9) if additional solids were being given, and 18-4 mg/100 ml (SD 7-81) for breast-fed babies. There was little difference between the plasma sodium levels of each group. The mean plasma sodium for all groups combined was 135-2 mmol/1 (SD 2-3); no plasma sodium exceeded 140 mmol/1.