Renal tubular acidosis

Hyperchloremic acidosis is a form of Metabolic acidosis associated with a normal anion gap, a decrease in bicarbonate, and in increase in chloride. more...

One of the most important causes of hyperchloremic acidosis is "renal tubular acidosis", or RTA.

RTA

Apart from the causes of increased acidity, there are four types of metabolic acidosis caused by the inability of the kidney to excrete acid. These conditions, termed renal tubular acidosis themselves have a number of potential (including hereditary) causes:

• Type 1 (distal) RTA: decreased acid secretion in the collecting ducts. The urine is relatively alkaline (pH>5.5)
• Type 2 (proximal) RTA: bicarbonate in pro-urine is poorly reabsorbed in the proximal tubules. It is usually mild, with bicarbonate levels between 14-20. It can be isolated, or part of a more generalized disorder with associated glycosuria, aminoaciduria and phosphaturia, termed as the Fanconi syndrome
• Type 3 RTA: occurs in children
• Type 4 RTA: this form occurs in deficiency of aldosterone, the principal mineralocorticoid. Aldosterone is required for the secretion of potassium and hydrogen in the distal tubules, as well as retention of sodium. In this type of RTA there is mild hyperkalemia and metabolic acidosis due to acid retention.

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