Proximal renal tubular acidosis.

The proximal tubule reabsorbs approximately 80% of the filtered load of bicarbonate. Defects in the process of bicarbonate reabsorption result in loss of bicarbonate and proximal renal tubular acidosis. Global proximal tubule dysfunction is known as the Fanconi's syndrome. Both isolated proximal renal tubular acidosis and the Fanconi's syndrome can result from inherited defects or can be acquired. This review will discuss the mechanisms that cause defects in proximal tubule bicarbonate transport as well as the common causes of isolated proximal renal tubular acidosis and the Fanconi syndrome.