The acidosis of cholera. Contributions of hyperproteinemia, lactic acidemia, and hyperphosphatemia to an increased serum anion gap

To study the metabolic acidosis that occurs during the diarrhea of cholera, we examined the serum anion gap in 21 patients with hypovolemic shock due to Vibrio cholerae infection. Measurements of serum electrolytes, as well as divalent cations and the anionic contributions of serum proteins, lactate, phosphate, and serum creatinine, were made at the time of admission, after rehydration, and during convalescence. At the time of admission, the mean serum concentration of sodium was 134.8 mmol (meq) per liter, that of chloride was 103.2 mmol per liter, and that of bicarbonate was 11.4 mmol per liter; the mean anion gap was 20.2 mmol per liter. The mean serum creatinine concentration was 2.48 mg per deciliter. The low serum bicarbonate level and the high serum anion gap were corrected by rehydration. The increased serum anion gap was caused by hyperproteinemia, lactic acidemia, and hyperphosphatemia, with anionic contributions to the rise in anion gap estimated as protein, 5.5 meq per liter; lactate, 2.5 meq per liter; and phosphate, 2.5 meq per liter. The hyperproteinemia was attributed to dehydration, the lactic acidemia to shock, and the hyperphosphatemia to acidosis and transient renal failure. The mean concentrations of serum calcium and magnesium were slightly elevated but did not affect the increased anion gap. These results indicate that severe cholera causes acidosis with relatively little change in serum chloride but an increased serum anion gap. The acidosis is more profound than would be expected on the basis of stool losses of bicarbonate, because of superimposed lactic acidemia and renal failure.