Dietary origin of retained H+ in infants with acquired monosaccharide intolerance

Net external acid balance was studied in 12 malnourished infants with chronic diarrhea (some of whom had acquired monosaccharide intolerance). When the infants achieved an adequate energy intake from a formula that contained either glucose or glucose polymers, seven developed metabolic acidosis and five remained free of acidosis. During the study, the acidotic infants produced a significant excess of acid (3.7 +/- 2 vs. 0.5 +/- 2 mEq/kg/day, p less than 0.005). The amount they excreted in urine (2.9 +/- 2 mEq/kg/day), however, was similar to that excreted by nonacidotic infants (2.7 +/- 2 mEq/kg/day) and indicated renal inability to reduce the excess acid load. The net effect was hydrogen ion (H+) retention (+0.8 +/- 0.8 vs. -2.2 +/- 0.8 mEq/kg/day, p less than 0.001). Good correlation existed between the net acid balance and the acid-base measurement in the blood. We speculate that (a) the increased acid load was a consequence of colonic bacterial production of volatile fatty acids from carbohydrate malabsorbed from the small bowel and (b) the renal incapacity to excrete H+ probably was secondary to potassium and phosphate depletion.