A frequent trouble in total parenteral nutrition is the occurrence of a negative calcium balance, due to reduction of calcium tubular reabsorption in acidosis. This condition could depend on acid metabolites raise, coming from degradation of nutritional amino acid mixtures. Authors have evaluated the effect of acetates addition to amino acid solutions on calcium balance. In fact the bicarbonate excess could reduce calcium urinary excretion. Thirty surgical patients have been treated. They were randomized according to acetates presence or absence in the administered solutions. In the acetate-treated group authors noted a raise in plasma bicarbonate and pH and a reduction in urinary calcium excretion. Adding acetates to amino acidic mixtures could reduce in total parenteral nutrition the risk of hypercalciuria and its related complications.