All issues > Volume 38(2); 1995

Original Article

J Korean Pediatr Soc. 1995;38(2):159-169. Published online February 15, 1995.

Clinical Studies of Metabolic Bone Disease of Prematurity

Seung-Yeon SY Suh¹, Eun-Kyung EK Lee¹, Ran R Namgung¹, Hae-Jung HJ Joo¹, Min-Soo MS Park¹, Kook-In KI Park¹, Chul C Lee¹, Dong-Gwan DG Han¹, Meung-Jun MJ Kim², Jin-Suk JS Suh²

¹Department of Pediatrics, College of Medicine, Yonsei University, Seoul, Korea
²Department of Radiology, College of Medicine, Yonsei University, Seoul, Korea

Abstract

Purpose
: Preterm formula used in Korea, theoretically does not supply the recommended mineral intake for optimal bone metabolism in very low birth weight infants(Formula 500-700 mg Ca/L, 300~370mg P/L, and 440IU of vitamin D/L). The purpose of this study is to identify th e possible etiologic factors and clinical course of rickets in these infants.
Methods
: We recently identified radiographic rickets or osteopenia in 16 VLBW infants over a 30-month period from January 1990, to July 1992. We performed a retrospective case analysis to evaluate the clinical features, nutritional status, biochemical and radiological findings o f metabolic disease in preterm infants.
Results
: Mean gestational age and birth weight were 29¡¾2.1wks, and 1172¡¾245gm. All infants received parenteral nutrition and 11 infants needed assisted ventilation. Enteral feeding w as started at a mean age of 9.4¡¾11.0d and mean total calorie intakes were 62¡¾16.2kcal/kg/d in the first 2wks and 111¡¾26.9kcal/kg/d at 2-4 wks of age. Oral Ca/P intakes were severely restricted during the first month of life, and they were about 20% of recommended intakes of Ca/P for VLBW infants. At diagnosis of active rickets, serum Ca was high in 19% and serum P wa s low in 69% of infants. Serum alkaline phosphatase was increased in 56% and serum 25-hydroxyvitamin D was low in 67%. Active rickets was diagnosed at mean age of 38¡¾14.7 d; 12 infants had overt rickets(grade 2), including 3 infants with fractures(grade 3). Healing rickets was diagnosed on follow-up at mean age of 67.3¡¾22.0 days. Thus, metabolic bone disease of VLB W infants was associated with low mineral intakes compared to recommended intakes, and signs of P deficiency occurred at about 2 wks of age and persisted to 8 wks of age; hypercalcemia occurred initially, and these biochemical abnormalities precede the radiological abnormalities about 2 or 3 weeks.
Conclusion
: Many factors are related to the development of metabolic hone disease of prematurity; one of the most important factor in our study was nutritional deficiency, especially m ineral(phosphorus) and vitamin D. In preterm VLBW infants whose adequate enteral feeding is restricted, mineral(calcium and phosphorus) and vitamin D supplementation would be needed t o reduce the development of metabolic bone disease in preterm infants.

Keywords :Metabolic bone disease, Preterm infants