What are the causes of isolated proximal (type 2) renal tubular acidosis (RTA)?

Updated: Dec 08, 2020
  • Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Isolated proximal RTA occurs sporadically, although an inherited form has recently been described. Homozygous mutations in the apical Na+/3HCO3- cotransporter have been found in 2 kindred with proximal RTA, band keratopathy, glaucoma, and cataracts. A form of autosomal recessive osteopetrosis with mental retardation is associated with a mixed RTA with features of both proximal and distal disease (called type 3). The mixed defect is related to the deficiency of carbonic anhydrase (CA II isoform) normally found in the cytosol of the proximal tubular cells and the intercalated cells of the collecting duct. The most common cause of acquired proximal RTA in adults follows the use of carbonic anhydrase inhibitors.

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