DISORDERS OF POTASSIUM, PHOSPHORUS, AND MAGNESIUM IN CRITICAL ILLNESS

Potassium, phosphorus, and magnesium are important for normal metaboli c and cellular functions. Serum concentrations of these primarily intr acellular ions are normally maintained within a narrow range by strict homeostatic mechanisms. Critically ill animals are prone to total bod y depletion or retention of these substances. These disorders must be corrected cautiously, with frequent monitoring to avoid severe side ef fects. Hypokalemia often results from decreased intake, excessive loss es (e.g., from renal disease, diarrhea, or vomiting), or translocation of potassium into cells (e.g., from initiation of insulin therapy). H yperkalemia can result from hypoadrenocorticism, acute oliguric renal failure, urethral obstruction, or massive cellular destruction. Hypoph osphatemia often occurs early in the treatment of malnutrition or diab etes. Hyperphosphatemia often results from renal failure. The importan ce of hypomagnesemia in critically ill patients has recently been reco gnized.