Renal tubular acidosis
Summary
Renal tubular acidosis (RTA) is a normal anion gap metabolic acidosis caused by impaired renal acid secretion or bicarbonate reabsorption despite normal GFR. Four types exist with different mechanisms.
Detail
Type I (Distal) RTA results from impaired H+ secretion in the collecting duct; urine pH remains >5.5 despite acidosis. Type II (Proximal) RTA involves reduced bicarbonate reabsorption in the proximal tubule. Type IV (Hyperkalemic) RTA reflects aldosterone deficiency or resistance. Diagnosis requires excluding high anion gap causes and calculating urine anion gap. Long-term consequences include nephrolithiasis (Type I) and bone demineralization. Treatment: alkali therapy for Types I and II, K+ restriction for Type IV.
Sources
- First Aid for the USMLE Step 1
- Pathoma
- Harrison's Principles of Internal Medicine
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.