Kidneys play a pivotal role in maintaining the acid-base balance of body along with lungs, and they do so by reabsorbing filtered bicarbonate and removing excess hydrogen ions. Renal disorders due to the removal of HCO3 or acid handling in the presence of relatively preserved GFR are collectively referred to as renal tubular acidosis. It is a non-anion gap hyperchloremic metabolic acidosis.
There are four subtypes of RTA. The three main subtypes of RTA correlate with three mechanisms that facilitate renal acid-base handling, i.e., proximal bicarbonate reabsorption mainly as a result of Na-H exchange (85% to 90%), distal hydrogen ion excretion-primarily a function of collecting tubules and generation of NH3, the principal urinary buffer .
The subtypes are as follows:
Type 1: Distal RTA
Type 2: Proximal RTA
Type 3: Mixed RTA
Type 4:Hyporeninemic hypoaldosteronism RTA
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