Renal Tubular Acidosis


The table below provides a useful summary of some of the key points in differentiating the types of renal tubular acidosis.

Comparison of Major Types of RTA


 Type 1

 Type 2

 Type 4

Hyperchloraemic acidosis




Minimum Urine pH


 <5.5 (but usually >5.5 before the acidosis becomes established)


Plasma potassium 




Renal stones





Reduced H+excretion in distal tubule

Impaired HCO3reabsorption in proximal tubule

Impaired cation exchange in distal tubule