Renal tubular acidosis in primary biliary cirrhosis.

The relationship between renal tubular acidosis (RTA) and copper metabolism has been investigated in a group of 18 patients with primary biliary cirrhosis. RTA, considered when urinary pH remained above 5.4 after an oral load of ammonium chloride of 0.1 g/kg body wt, was found in 6 patients (33%). Plasma copper concentration (PCu) and urinary copper excretion (UCuV) were significantly higher in patients with RTA (PCu = 182.2 micrograms/dl, UCuV = 536.8 micrograms/24 h) than in those without (PCu = 134.2; UCuV = 170.3). Plasma copper concentration and urinary copper excretion correlated with minimal urinary pH achieved after the ammonium chloride load. A higher degree of cholestasis was present in patients with RTA than in those without, and a linear correlation was observed between PCu and UCuV and serum bilirubin. It is concluded that the increased UCuV is related to the cholestasis in primary biliary cirrhosis and that the RTA might be caused by the deposition of copper in the distal renal tubule.