Type 4 RTA — RACP Paediatrics MCQ

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HardNephrologyType 4 RTARACP Paediatrics

A premature infant on spironolactone develops a normal anion gap metabolic acidosis with hyperkalaemia. Urine pH is acidic (<5.5). Aldosterone levels are elevated. What is the most likely type of RTA?

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Correct answer: A — Type 4 RTA

Type 4 RTA is characterised by hyperkalaemia with normal anion gap metabolic acidosis. The urine CAN acidify (pH <5.5), distinguishing it from distal RTA. It is caused by aldosterone deficiency or resistance. Common causes in children include drugs (spironolactone, ACE inhibitors), obstructive uropathy, and adrenal insufficiency.

Reference: RCH Melbourne – 2023 – RTA CPG; RACP Paediatric Curriculum – Nephrology