ACID PRODUCTION IN CHRONIC-HEMODIALYSIS PATIENTS

This study examines endogenous acid production in a group of stable ch ronic hemodialysis patients with no residual renal function who were a dmitted to the chronic hemodialysis unit of Mount Sinai Hospital. Net acid production was estimated by the change in body bicarbonate conten t, which occurs in the interdialytic period. The body bicarbonate cont ent at any time was measured by multiplying the concentration of blood bicarbonate by the apparent bicarbonate space at that time. The appar ent bicarbonate space was determined by the change in blood bicarbonat e concentration induced by the intravenous administration of a known a mount of sodium bicarbonate. Daily sulfuric acid production was also e stimated from the reduction in body sulfate content during dialysis. T he interdialytic net acid production was measured at approximately 28 mEq/d, a value much lower than that predicted from the protein catabol ic rate. This reduced acid production can be explained by reduced sulf uric acid and organic acid production. The mechanism of reduced sulfur ic acid production is unknown. Reduced organic acid production is expl ained partly by the absence of renal excretion of metabolizable organi c anions, leaving only the nonmetabolizable fraction as the main sourc e of acid in the interdialytic period.