Metabolic bone disease in low birth weight babies between 1500 and 2000 g on exclusive breast feeding

Abstract

Background: Metabolic bone disease of prematurity due to reduced bone mineralization is mostly described in infants of less than 1500 g. Although various guidelines recommend calcium and phosphate supplementation for low birth weight (LBW) newborns less than 1500 g and on exclusive breast feeding but there are no guidelines for those weighing above 1500 g and on exclusive breast feeding. Moreover, there is insufficient data on incidence of rickets and serum biochemical status in these babies of birth weight more than 1500g and on unsupplemented breast feeding and among term growth retarded babies. Objectives: To determine the incidence of rickets and changes in biochemical profile including serum calcium, phosphate, and alkaline phosphatase in preterm appropriate for gestational age (PTAGA) and term small for date (TSFD) babies with birth weight between 1500 and 2000 g and on unsupplemented breast feeding. Materials and Methods: It is an observational cohort study done at a tertiary care centre in northern India over a period of one year, including LBW babies between 1500 and 2000 g and on unsupplemented breast feeds. In group I, 116 PTAGA babies with birth weight 1500-2000g and on unsupplemented breast feeds were enrolled and 100 PTAGA babies completed follow up till 6 months. In group II 124 TSFD babies with birth weight 1500-2000 g and on unsupplemented breast feeds were enrolled and 100 TSFD babies completed follow up till 6 months. Biochemical parameters were done at baseline (before discharge) and were followed-up for a period of 6 months. Radiological assessment was done if clinical features of rickets appeared or serum biochemistry was suggestive of rickets. Results: Both groups, of babies, developed progressive decrease in serum calcium and phosphate levels, which was statistically significant as shown by time trend. Serum alkaline phosphatase showed significant increase from baseline in both the groups. Fourteen out of 200 (7%) babies developed radiological rickets at end of 3 months, which increased to 34/200 (17%) at end of 6 months. Serum alkaline phosphatase showed most consistent correlation with occurrence of rickets. Conclusion: LBW babies 1500-2000 g and on exclusive breast feeding are at significant risk of developing metabolic bone disease including rickets and need extra supplementation with calcium and phosphate besides Vitamin D.