S2581 Distal (Type I) Renal Tubular Acidosis Associated With Primary Sclerosing Cholangitis

Abstract

INTRODUCTION: Distal Renal Tubular Acidosis (dRTA) is associated with conditions such as Sjogren's syndrome, lupus, rheumatoid arthritis, primary biliary cholangitis, autoimmune hepatitis, Wilson disease and other conditions. We present a case of a 25-year-old man with primary sclerosing cholangitis (PSC) presenting with dRTA. CASE DESCRIPTION/METHODS: A 25-year-old man with a history of decompensated cirrhosis due to primary sclerosing cholangitis complicated by encephalopathy, esophageal varices presented to the hospital with worsened hepatic encephalopathy. His serum chemistries revealed hypokalemia and non-anion gap metabolic acidosis [serum sodium 140 mEq/L (normal: 136-145), serum potassium 3.3 mEq/L (normal: 3.5-5.1), serum chloride 116 mEq/L (normal: 98-107), serum bicarbonate 16 mEq/L (normal: 22-32), serum albumin 2.3 g/dl (normal: 3.4-5), bilirubin 37.4 mg/dl (normal < 1), alkaline phosphatase 151 U/L (normal: 45-117), aspartate aminotransferase 222 U/L (normal: 15-37), alanine aminotransferase 128 U/L (normal: 16-61)]. Work up was initiated to evaluate the cause of non-anion gap metabolic acidosis. In absence of fistula, ileal conduit, diarrhea, contributing medications, hyperparathyroidism or saline administration with urinary pH 6.0, urine osmolal gap 15, urinary sodium 84 mEq/L, normal urine uric acid and amino acid excretion, a diagnosis of dRTA in the setting of PSC was made. Acidosis was corrected by supplementation of bicarbonate. Encephalopathy responded to lactulose/rifaximin administration. Patient underwent liver transplantation for decompensated cirrhosis which was curative in resolving his dRTA. DISCUSSION: Distal type I renal tubular acidosis (dRTA) may be hereditary, associated with autoimmune diseases (Sjogren, lupus, rheumatoid arthritis and others), chemotherapy drugs or toluene intoxication. In GI realm, dRTA has traditionally been associated with primary biliary cholangitis, autoimmune hepatitis and Wilson disease. Putated mechanisms for its pathogenesis involve gene mutation in hereditary forms, antibodies against vacuolar H+-ATPase, carbonic anhydrase II enzymes in autoimmune forms, direct toxic effect of bilirubin on the renal tubules in cholestatic conditions. Correction of acidosis should be accomplished using potassium citrate – potassium bicarbonate tablets as they contain more mEq of bicarbonate per tablet than commonly used sodium bicarbonate. This abstract helps raise awareness amongst fellows and practicing gastroenterologists in recognizing PSC as a cause of dRTA.