All issues > Volume 28(10); 1985

Original Article

J Korean Pediatr Soc. 1985;28(10):967-976. Published online October 31, 1985.

A Study on Calcium Metabolism in Newborn Infants.

Jin Heon Kim, Chang Soo Ra

¹Department of Pediatrics,College of Medicine, Chosun University

Abstract

A thorough understanding of calcium homeostasis and metabolism in newborn infants is necessary in the evaluation of any newborn infant with hypocalcemia. Author studied the levels of urinary calcium and phosphorus during the 48 hours after birth, and also studied before and after feeding during the 24 hours after birth in 19 normal term infants. And serum calcium, phosphorus, parathormone, and calcitonin were serially studied in 8 low birth weight infants during the first 4 days after birth. The serum and urinary calcium level was measured by 0-CPC colorimetric method, and serum and urinary phosphorus, by-Fiske and Subbarow method. The serum parathormone level was measured by the method of radioimmunoassay(INC® C-terminal hPTH kit) and serum calcitonin level was measured by the method of radioimmunoassay (INC® Calcitonin fl kit). The following results were obtained; 1) The mean level of urinary calcium excretion for the first day after birth in normal term infants was 0.33±0.23 mg and that of urinary calcium excretion for the second day was 0.19±0.18 mg. Urinary calcium excretion was found to be significantly higher in the first day than the second day after birth. The difference of urinary calcium excretion level between the first day and the second day was statistically significant (p<0.05). The mean level of urinary phosphorus excretion for the first day after birth in normal term infants was 0.18±0.19 mg and that of urinary phosphorus excretion for the second day was 2.47±5.09 mg. Urinary phosphorus excretion was found to be significantly higher in the second day than the first day after birth. The difference of urinary phosphorus excretion level between the first day and the second day was statistically not significant (P〉0.05). 2)The mean level of urinary calcium before the first feeding in normal term infants was 1. 34±1.53 mg/dl and that of urinary calcium after feeding was 0.30±0.26 mg/dl. Urinary calcium level was found to be significantly lower after feeding than before the first feeding. The difference of urinary calcium level between before the first feeding and after feeding was statistically significant(p<0,01). The mean level of urinary phosphorus before the first feeding in normal term infants was 0.30±0.29 mg/dl and that of urinary phosphorus after feedin was 4.47±7.72 mg/dl. Urinary phosphorus level was found to be significantly higher after feeding than before the first feeding. The difference of urinary phosphorus level between before the first feeding and after feeding was statistically not significant (p>0.05). 3)The mean variation range during the first 4 days after birth in low birth weight in fants of serum calcium was the lowest level with 7.47±1.67 mg/dl on the 48 hours after birth. The mean variation range during the first 4 days after birth in low birth weight infants of serum phosphorus was the highest level with 7.3±3.9 mg/dl and of serum parathormone was the highest level with 0.84土0.55 ng/ml and of serum calcitonin was the highest level with 568.3±275.2 pg/ml on the 48 hours after birth. 4)The mean level of serum calcium in low birth weight infants was the lowest level on the 48 hours during the first 4 days after birth and of serum phosphorus was the highest level on the 48 hours during the first 4 days after birth. The mean level of urinary calcium excretion in low birth weight infants during the first 4 days after birth was increasing and that of urinary phosphorus excretion was increasing. But urinary phosphorus excretion in low birth weight infants was significantly lower than normal term infants. 5)In conclusion, above results suggest that early neonatal hypocalcemia may occur during the 48 hours after birth, and low birth weight infants are to be susceptable to the development of hypocalcemia and are slower than the normal term infants in regulating this calcium homeostasis.

Keywords :Newborn infants; Calcium metabolism; Neonatal hypocalcemia