[A case of hyperammonemia in chronic renal failure successfully treated with the infusion of NaHCO3]

The present report describes a rare of a 77-year-old woman who developed encephalopathy and metabolic acidosis associated with hyperammonemia, at the introduction of hemodialysis by chronic renal failure. With the intravenous infusion of HCO3-, levels of acidosis and hyperammonemia decreased rapidly. Concomitantly the disturbance of consciousness was improved. Results of plasma amino acid patterns of pre and post infusion of HCO3- showed improvement of the metabolism of the urea cycle, increased urea synthesis and decreased plasma ammonium levels. The role of the hepatic urea cycle has been considered to be exclusively the elimination of potentially toxic ammonia. In the conventional view, the acid base balance of the body obtains stabilized homeostasis by the function of the principal organs, lungs and kidneys. But, it has been recently shown that urea cycle is an important factor in the maintenance of pH homeostasis, due to regulated metabolism of HCO3-. Both HCO3- and NH4+ are converted to urea indicating the urea cycle's involvement in acid base homeostasis. 2HCO3- + 2NH4+-->urea+CO2+3H2O In this case, with the infusion of HCO3, the metabolism of the urea-cycle was improved and plasma ammonium levels were decreased. This indicates that HCO3- is an important factor for the metabolism of ammonia.