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: 1. Type 1: Distal RTA. 2. Type 2: Proximal RTA. 3. Type 3: Mixed RTA. 4. Type 4:Hyporeninemic hypoaldosteronism RTA.
肾脏与肺脏一起在维持身体酸碱平衡方面发挥着关键作用，它们通过重吸收滤过的碳酸氢盐和去除多余的氢离子来实现这一点。在肾小球滤过率（GFR）相对保持正常的情况下，由于碳酸氢根离子（HCO3）的重吸收或酸处理功能异常而导致的肾脏疾病统称为肾小管酸中毒。这是一种非阴离子间隙性高氯性代谢性酸中毒。肾小管酸中毒有四种亚型。肾小管酸中毒的三种主要亚型与促进肾脏酸碱处理的三种机制相关，即近端碳酸氢盐重吸收主要是由于钠氢交换（85%至90%）、远端氢离子排泄——主要是集合管的功能以及氨（主要的尿液缓冲物质）的生成。这些亚型如下：1. 1型：远端肾小管酸中毒。2. 2型：近端肾小管酸中毒。3. 3型：混合型肾小管酸中毒。4. 4型：低肾素性低醛固酮血症性肾小管酸中毒。
