Visual, microscopic, and colorimetric examination of calcium and magnesium levels in parenteral nutrition solutions containing 6 percent amino acids, 25 percent dextrose, and 65 mMol of phosphorus/L

When compounding parenteral nutrition (PN) solutions, enhancing the solubility of calcium and phosphate in the solutions is a challenge of great clinical importance. It has been suggested that magnesium plays a role in the compatibility between calcium and phosphate. Three levels of magnesium were added to solutions containing 6% amino acids, 25% dextrose, 65 mMol of phosphorous/L, and varying levels of calcium. Visual inspection, microscopic examination, pH analysis, and colorimetric analysis were performed immediately alter compounding and alter heating the solutions, to determine the effects of magnesium on calcium-phosphate compatibility. Visual observation with the naked eye was found to be a reliable and practical means of detecting particles in PN solutions after 32 hours. It was confirmed, using both microscopic examination and colorimetric analysis, that increased amounts of magnesium (24 or 40 mEq magnesium/L) in PN solutions have a protective effect against calcium phosphate precipitation (p values = .001, .037).