Approach to Renal Tubular Acidosis – A Review

Acid-base homeostasis is maintained by renal and respiratory systems. The inability of the renal tubules to excrete acids or retain bicarbonate in adequate amounts leads to renal tubular acidosis (RTA). These disorders are characterised by the presence of normal anion gap metabolic acidosis with hyperchloremia. Both distal RTA (type 1) and proximal RTA (type 2) can occur due to a primary/inherited defect in the renal tubule or may arise due to some secondary/acquired causes. Urinary acidification defect defines type 1 RTA, while type 2 RTA is characterised by defective bicarbonate handling in the proximal tubule. Type 3 RTA includes features of both type 1 and type 2 RTA, whereas type 4 RTA is characterised by the presence of hyperkalaemia with normal anion gap metabolic acidosis. In this review article, we describe the various types of RTA and its pathophysiology along with a systematic and practical approach to a suspected case of RTA and its management.