Calcium and phosphorus in neonatal parenteral nutrition solutions

Due to calcium and phosphorus solubility problems in parenteral nutrition solutions, it is difficult to provide the premature infant with enough of these two minerals for adequate bone mineralization. In order to determine the maximum amounts of both Ca and P soluble in neonatal parenteral nutrition solutions, we employed the following procedure: (1) using concentrations of dextrose 10 to 25% and amino acid 0.5 to 4.0% with standard electrolyte and vitamin concentrations, Ca and P additions were sequentially made to determine the critical concentrations at which precipitates formed; (2) the pH of each test solution was determined; (3) all test solutions were incubated for 30 hr at room temperature; (4) following incubation, all tests were visually observed for calcium-phosphate crystals; (5) the solutions not obviously precipitated were filtered using black Millipore filters to determine the presence of any microprecipitates. Multiple graphs of Ca and P solubility in various dextrose/amino acid solutions were prepared from data generated by the study. The Ca and P interaction is primarily pH sensitive. Factors affecting the solution pH include both dextrose and amino acid concentrations. Our study showed that increases in amino acid concentrations enabled us to increase both Ca and P in the solutions.