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Renal tubular acidosis


  • Type I (distal H+ secretion defect): low serum K+, urine pH >5.5, associated with autoimmune disease, hypercalcemia
  • Type II (proximal HCO3- reabosrbtion defect): low serum K+, urine pH < 5.5, associated with multiple myeloma, drugs (eg, sulfa)
  • Type III (rare): normal serum K+, urine pH < 5.5, associated with renal insufficiency
  • Type IV (hyporeninemic hypoaldosteronism): high serum K+, urine pH < 5.5, associated with diabetes mellitus, drugs (eg, NSAIDs)


Other causes of normal gap metabolic acidosis

  • Gastrointestinal loss of HCO3-, eg, diarrhea, pancreatic ileostomy or ileal loop bladder
  • Renal tubular acidosis
  • Recovery from diabetic ketoacidosis
  • Dilutional acidosis from rapid administration of 0.9% NaCl
  • Carbonic anhydrase inhibitors
  • Chloride retention or administration of HCl equivalent or NH4Cl

See related DDx

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Last updated: December 1, 2014


Zeiger, Roni F.. "Renal Tubular Acidosis." Diagnosaurus, 4th ed., McGraw-Hill Education, 2014. Emergency Central, emergency.unboundmedicine.com/emergency/view/Diagnosaurus/114288/all/Renal_tubular_acidosis.
Zeiger RF. Renal tubular acidosis. Diagnosaurus. 4th ed. McGraw-Hill Education; 2014. https://emergency.unboundmedicine.com/emergency/view/Diagnosaurus/114288/all/Renal_tubular_acidosis. Accessed April 25, 2019.
Zeiger, R. F. (2014). Renal tubular acidosis. In Diagnosaurus. Available from https://emergency.unboundmedicine.com/emergency/view/Diagnosaurus/114288/all/Renal_tubular_acidosis
Zeiger RF. Renal Tubular Acidosis [Internet]. In: Diagnosaurus. McGraw-Hill Education; 2014. [cited 2019 April 25]. Available from: https://emergency.unboundmedicine.com/emergency/view/Diagnosaurus/114288/all/Renal_tubular_acidosis.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Renal tubular acidosis ID - 114288 A1 - Zeiger,Roni F, Y1 - 2014/12/01/ BT - Diagnosaurus UR - https://emergency.unboundmedicine.com/emergency/view/Diagnosaurus/114288/all/Renal_tubular_acidosis PB - McGraw-Hill Education ET - 4 DB - Emergency Central DP - Unbound Medicine ER -