847 NEONATAL HYPOCALCEMIA ASSOCIATED WITH MATERNAL HYPERCALCEMIA

Abstract

An infant born to a mother with hypercalcemia secondary to metastatic breast cancer developed severe hypocalcemia during the first week of life. Maternal calcium and phosphorous levels ranged from 14-17 mg/dl and 2-2.5 mg/dl, respectively, prior to delivery, and the infant's calcium level was 15.0 mg/dl at birth. During the first 9 days of life the infant's serum Ca level decreased to 4.8 mg/dl and P rose to 8.4 mg/dl. The serum Mg decreased to 0.7 mg/dl. Administration of MgSO4 intramuscularly raised the serum Mg to normal levels, but hypophosphaturia and hypocalcemia persisted. Administration of PTH was followed by return of Ca to normal levels and an apparent increase in P excretion. When PTH was stopped, serum Ca and Mg again decreased, but the phosphaturia persisted. Ca and Mg levels returned to normal spontaneously by the fourth week of life. The hypocalcemia of this infant supports the hypothesis of transient neonatal hypoparathyroidism resulting from exposure to relatively high levels of maternal Ca in utero and contradicts the theory that it is related to Mg deficiency and end-organ unresponsiveness to PTH.