A case of Fanconi syndrome with type 1 renal tubular acidosis.

A 32-year-old woman of Fanconi syndrome with disorders of amino acid, glucose, uric acid and phosphate reabsorption system in proximal tubule and of renal acid excretion mechanism in distal tubule was reported. By the ammonium chloride loading test, urinary pH could only be decreased by 5.9, and excretion rates of NH4+ and titratable acids were 18.9 and 31.1 mEq/min, respectively. In the bicarbonate loading test, net renal reabsorption of bicarbonate was 2.86 mEq/100 ml GFR when plasma bicarbonate concentration was 29 mEq/L, and threshold of bicarbonate excretion was 24-26 mEq/L. These results suggest that hydrogen ion excretion disorder in distal tubules exists, while bicarbonate reabsorption ability in proximal tubule is normal.