Sodium supplementation in very low birth weight infants fed on their own mothers milk: II. Effects on protein and bone metabolism.

We determined serum calcium, inorganic phosphate, alkaline phosphatase, total protein and albumin levels in a group of 66 very low birth weight (VLBW) preterm infants seen at Kenyatta National Hospital. We used these parameters as markers to study the effect of sodium supplementation on protein and bone metabolism in VLBW infants fed on their mothers' milk. 41 of the infants were supplemented with 3 mMol/kg/day sodium chloride for a duration of six weeks of postnatal life. The remaining group were fed only on their mothers' milk. Results indicated significantly increased serum levels of calcium (P < 0.01) in the non-supplemented group while inorganic phosphate and total protein levels showed significant increase (P < 0.05) in the supplemented group. Both groups had increased levels of osteoblastic activity accompanied by high rate of protein synthesis in the supplemented group compared to the non-supplemented one. These findings together with a significant difference in growth rate (P < 0.01) observed between the two groups indicate that sodium supplementation may have a significant effect on the rate of bone mineralization and protein synthesis in VLBW infants.