Serum Magnesium Levels in the Newborn

Two hundred and thirty-eight determinations of serum magnesium levels during the first 4 days of life were carried out on 78 infants. No statistically significant differences were found when these values were compared to those determined in 111 older children and adults. Differences in mean values between any of the first 5 days were not statistically significant nor were any significant differences found when the values of each day were compared with the mean value of older children and adults or the mean value of the cord bloods. The mean values on days 3, 4, and 5 were higher in breast-fed infants than in infants fed evaporated milk. Higher values in breast-fed infants and lower values in evaporated-milk-fed infants on days 3 and 4 when compared to day 1 in the same infant were found in a significant number of cases. The possibility that the observed differences in these two groups of infants may be related to the difference in phosphate to magnesium ratio in cow's milk as compared to human milk is discussed. Further investigation of this problem is needed before definite conclusions can be drawn.