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Fludrocortisone Type 4 RTA — ESENeph MCQ

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HardAcid-BaseFludrocortisone Type 4 RTAESENeph

A 45-year-old woman with type 4 RTA (hyporeninemic hypoaldosteronism) from diabetic nephropathy has persistent potassium of 5.8 mmol/L despite dietary restriction. She is on Ramipril which worsens the hyperkalaemia. She cannot tolerate an alternative RASi. What specific treatment targets the aldosterone deficiency?

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Correct answer: B — Fludrocortisone (mineralocorticoid replacement)

Type 4 RTA from hyporeninemic hypoaldosteronism (common in diabetic nephropathy) causes hyperkalaemia through aldosterone deficiency. Fludrocortisone (a synthetic mineralocorticoid) directly replaces the deficient aldosterone, promoting renal potassium excretion. However, it must be used cautiously as it causes sodium retention, hypertension, and fluid overload – problematic in patients with CKD who already have these tendencies. Low doses (50-100 mcg daily) are used. Potassium binders are an alternative approach.

Reference: Rodríguez-Soriano 2002 – RTA; KDIGO 2024 – CKD