Nutrition-focused evaluation and management of dysnatremias.

Alterations in sodium and water balance are commonplace and often occur concurrently. Dysnatremias (hyponatremia and hypernatremia) merely reflect a relative excess or deficit of plasma water in relation to plasma sodium. There is no predictable relationship between plasma sodium concentration, extracellular fluid volume, and total body sodium content. Evaluation and management of dysnatremias rely on an understanding of key terminology, normal body fluid composition and distribution, and regulation of water and sodium balance, combined with a directed history and physical and appropriate laboratory tests. Enteral and parenteral nutrition regimens can be modified to help restore normal plasma sodium concentrations. Response to treatment requires close monitoring to avoid potential complications associated with rapid correction of hyponatremia and hypernatremia.