CLASSICAL (DISTAL) RENAL TUBULAR ACIDOSIS: ENDOGENOUS ACID PRODUCTION

Abstract

It has been shown by McSherry et al (Clin Res 21:229, 1973), that children with classical (distal) renal tubular acidosis (cRTA) can achieve normal growth with sustained correction of acidemia by aggressive alkali therapy of up to 6-10 mEq/kg/day. To test the hypothesis that such patients have a marked increase in endogenous production of non-volatile, non-carbonic acid, incident to “catch-up” growth, three children aged 3-10 years with cRTA were each studied for three weeks by the methods of Relman et al (JCI 40:1621, 1961) regarding the rate of endogenous acid production. Mean values of patients and the twelve controls (in brackets) are presented in mEq/kg/day: sulfuric acid production, 2.5 ± 0.2 (1.3 ± 0.3); hydrogen ion production incident to incomplete oxidation of organic acid, 0.9 ± 0.2 (1.0 ± 0.4) and total net acid production, 3.4 ± 0.2 (2.3 ± 0.1). Stepwise increments of the bicarbonate therapy from 2 to 6 mEq/kg/day corrected the acidemia but did not alter the rate of endogenous acid production. The data indicate that the rate of endogenous acid production in these children with cRTA is 30% higher than comparable, healthy children and the increased sulfuric acid production accounts, in large part, for this elevation. It is concluded that the metabolism of sulfur-containing amino acids is accelerated, the exact mechanism of which requires further study.