Sequential Nephron Blockade Monitoring — ESENeph MCQ

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EasyElectrolyte DisordersSequential Nephron Blockade MonitoringESENeph

A 28-year-old woman with nephrotic syndrome from focal segmental glomerulosclerosis has persistent oedema despite Furosemide 80 mg BD. Adding Metolazone is planned. What monitoring is essential when combining loop and thiazide diuretics?

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Correct answer: E — Monitor weight, electrolytes and renal function

The combination of loop and thiazide diuretics produces potent synergistic diuresis (sequential nephron blockade). This carries significant risk of severe hypokalaemia, hyponatraemia, hypomagnesaemia, metabolic alkalosis, and prerenal AKI. Monitoring should include daily weight, strict fluid balance, and electrolytes within 24-48 hours of starting the combination. Metolazone is typically used intermittently (not daily) due to its potency. IV electrolyte replacement may be needed. The competing options do not fit the renal phenotype, temporal relationship, treatment threshold or safety constraint described. Management still requires confirmation of current medicines, renal trajectory and relevant contraindications, followed by timely biochemical and clinical reassessment. Escalate urgently if life-threatening electrolyte disturbance, respiratory compromise, shock, neurological deterioration or a dialysis indication develops.

Reference: NICE CG108 – Heart Failure; KDIGO 2024 – CKD: https://kdigo.org/guidelines/gd/