A patient with type 1 RTA (distal RTA) has which characteristic set of findings?
- A Hyperchloraemic metabolic acidosis, urine pH < 5.5, hypokalemia, nephrolithiasis
- B Hyperchloraemic metabolic acidosis, urine pH > 5.5, hypokalemia, nephrocalcinosis ✓
- C Anion gap metabolic acidosis, urine pH > 5.5, hyperkalemia
- D Hyperchloraemic metabolic acidosis, urine pH < 5.5, hyperkalemia, low serum aldosterone
Correct answer: B. Hyperchloraemic metabolic acidosis, urine pH > 5.5, hypokalemia, nephrocalcinosis
Explanation
Type 1 (distal) RTA is characterised by failure to acidify urine distally, resulting in: hyperchloraemic non-anion-gap metabolic acidosis, urine pH persistently >5.5 even during systemic acidosis, hypokalaemia (due to increased H⁺/K⁺ exchange), nephrocalcinosis, and nephrolithiasis (calcium phosphate stones). Type 4 RTA (hypoaldosteronism) causes HYPERKALEMIA and urine pH < 5.5. Type 2 (proximal) RTA has urine pH < 5.5 with Fanconi syndrome.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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