Total parenteral nutrition-associated metabolic acidosis.

To prevent acid-base disturbances, a patient receiving intravenous nutritional solutions must excrete the daily metabolic production of acid. These hydrogen ions are generated from external (infused) sources and internal metabolic processes. Patients with normal respiratory and renal organ function are capable of excreting these volatile and nonvolatile acids, respectively, and maintaining acid-base balance. However, increased renal or gastrointestinal loss of bicarbonate, diminished renal excretion of acid, or increased acid production may all result in a metabolic acidosis. This article reviews the mechanisms of hydrogen ion production associated with total parenteral nutrition and the variety of disease states leading to development of a metabolic acidosis.