Updated: 12/13/2017

Renal Tubular Acidosis (RTA)

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  • A 36-year-old woman presents to the emergency department with left-sided back pain that radiates to her left groin. Medical history is significant for Sjogren syndrome. On physical exam there is left-sided costovertebral angle tenderness. Laboratory testing is notable for hyperchloremic and normal anion gap metabolic acidosis and hypokalemia. Non-contrast computerized tomography (CT) of the abdomen demonstrates urolithiasis. She is started on ibuprofen and intravenous fluids. Once the calculi passed it was found to be a calcium phosphate stone. (Type I renal tubular acidosis)
  • Clinical definition
    • renal tubular dysfunction that results in a hyperchloremic and normal anion gap metabolic acidosis
      • there is a relatively normal glomerular filtration rate
Renal Tubular Acidosis
Pathogenesis Treatment Comments
Type II (proximal) 
  • Fanconi syndrome
  • Carbonic anhydrase II deficiency
  • Medications
    • acetazolamide
    • ifosfamide
    • topiramate
    • expired tetracyclines
  • Heavy metals
    • e.g., mercury, cadmium, copper, and lead
  • Multiple myeloma
  • Wilson disease
  • ↓ bicarbonate reabsorption in the proximal tubule
  • Potassium citrate
  • Thiazide diuretics
  • Associated with hypokalemia
  • At risk of developing hypophosphatemic rickets
  • Urine pH is initially > 5.5 and then later becomes < 5.5
Type I (distal)
  • Sjogren syndrome
  • Rheumatoid arthritis
  • Anion exchanger gene mutations
  • Medications
    • lithium
    • ifosfamide
    • analgesics
    • amphotericin B
  • Defective hydrogen secretion
  • Sodium bicarbonate or sodium citrate
  • Associated with hypokalemia
  • At risk of developing calcium phosphate stones
  • Urine pH > 5.5
Type IV (hyporeninemic hypoaldosteronism)
  • Diabetic nephropathy
  • Mineralocorticoid deficiency
  • Sickle cell disease
  • Systemic lupus erythematosus
  • Medications
    • heparin
    • angiotensin converting enzyme (ACE) inhibitors
    • angiogensin receptor blockers (ARBs)
    • cyclosporine
    • TMP-SMX
    • potassium sparing diuretics
  • Hyperkalemia results in ↓ ammonia (NH3) synthesis
    • ↓ the capacity to carry acid
  • Treatment depends on the underlying cause
  • Associated with hyperkalemia
  • Urine pH < 5.5

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