July 1976 The Journal o f P E D I A T R I C S

115

Hypomagnesemia in infants of diabetic mothers." Perinatal studies Fifty-six diabetic mothers and their infants were studied prospectively from birth. Twenty-one of 56 I D M had serum Mg 130/90 mm Hg, edema, and proteinuria), diuretic usage during pregnancy, m o d e of delivery, duration of labor, one minute A p g a r score, sex, race, birth weight, respiratory distress, acidosis, or administration of sodium bicarbonate for acidosis. Mothers of H M infants were younger (t test, p < 0.01), and of lower gravidity (p < 0.005) than mothers of N M infants (Table II). H M infants were of lower gestational age (p < 0.05). "Jitteriness" was not related to HM, or H M associated with hypocalcemia (defined as serum concentration of Ca < 7 m g / d l or, serum ionized Ca < 3 mg/dl. Serum Ca, ionized Ca, phosphate, and blood pH and

Hypomagnesemia in infants o f diabetic mothers

Volume 89 Number 1

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glucose. Serum concentrations of Ca in H M infants were significantly lower than values in N M infants at 24 and 72 hours of age, respectively (t test, p < 0.05, Fig. 1). Serum concentration of Ca at 72 hours correlated with simultaneously obtained serum Mg (r = 0.582, p < 0 . 0 1 ) . Seventy-two percent of H M infants had simultaneous serum concentrations of Ca < 8 mg/dl; 64% had serum Ca < 7 mg/dl. Ionized Ca was lower in H M infants at 24 to 48 hours of age. Serum ionized Ca at 72 hours correlated with serum Mg at 24 hours (r = 0.424, p < 0.05). All ten H M infants who had simultaneous determinations of serum ionized Ca had levels < 3 mg/dl, including four of 10 with levels < 2 mg/dl. At 48 or 72 hours of age, higher serum concentrations of P were related to lower simultaneous levels of serum Mg (r = 0.382 and r = -0.351, respectively, p < 0.05). Blood pH (Fig. 1) and lowest blood glucose values (Table 1I) in H M infants were not different from those in N M infants. Maternal serum concentrations of Mg. Serum concentrations of Mg at birth in IDM and at all postnatal ages studied were significantly related to maternal serum concentrations of Mg (r = 0.434 to 0.751, p < 0.01). Maternal serum levels of Mg did not correlate with the severity of diabetes. Renal excretion of Mg, Ca, P, dietary P. The daily 24 hour urinary excretion of Mg, Ca, P, and dietary P intake for the first three days of life were not different between HM and normomagnesemic IDM. For the first 24 hours,

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