Electrolyte balance in gastrointestinal disease.

Even small losses of gastrointestinal secretions when combined with reduced intake of electrolytes may seriously disturb electrolyte balance. Knowledge of the ionic composition of secretions lost is essential in planning therapy. Loss of gastric contents usually results in excessive loss of chloride; in achlorhydria this is not the case. Loss of sodium and potassium may be large in either case and is often underestimated. Small bowel obstruction results in a more balanced loss of electrolyte which may not affect acidbase balance greatly. In diarrhea loss of base predominates, and may result in a large potassium deficit. Steatorrhea due to nontropical sprue results in large fecal losses of sodium, potassium and chloride, in addition to the large calcium and phosphorus loss. In chronic peptic ulcer excessive ingestion of milk and absorbable alkalies may result in hypercalcemia, azotemia and alkalosis, without hypercalciuria. Since renal function is usually adequate in the milder gastrointestinal disturbances, electrolyte and fluid replacement should be started early, and can be guided by generally available laboratory tests, the carbon dioxide combining power and serum chloride levels, provided the predominate ionic loss is known and potassium deficiency remedied. If this is done, development of serious fluid and electrolyte deficits can usually be prevented.