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Distal RTA — RACP Paediatrics MCQ

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HardNephrologyDistal RTARACP Paediatrics

A 6-year-old boy presents with failure to thrive, polyuria, polydipsia, and a non-anion-gap metabolic acidosis (pH 7.28, bicarbonate 14 mmol/L). Urine pH is inappropriately alkaline (pH 7.0). Serum potassium is low. What is the diagnosis?

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Correct answer: A — Distal (type 1) renal tubular acidosis

Distal RTA (type 1): inability to acidify urine (urine pH >5.5 despite systemic acidosis), non-anion-gap metabolic acidosis, hypokalaemia, and failure to thrive. Complications include nephrocalcinosis and rickets. Treatment is oral alkali supplementation (sodium bicarbonate or potassium citrate).

Reference: RCH Melbourne – 2024 – Clinical Practice Guidelines: Renal Tubular Acidosis