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Lithium and thiazide — GPhC CRA MCQ

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HardDrug InteractionsLithium and thiazideGPhC CRA

A 75-year-old woman taking lithium is newly prescribed bendroflumethiazide 2.5mg daily for hypertension. Her eGFR is 50mL/min/1.73m2 and lithium level was 0.8mmol/L last month. What monitoring is required?

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Correct answer: D — Lithium level and renal function review because thiazides can increase lithium levels

Thiazide diuretics can reduce lithium clearance and increase lithium concentrations. Older age and reduced renal function further increase toxicity risk. Lithium level and renal function should be checked according to prescriber or specialist advice, with patient counselling on toxicity symptoms. The interaction may require alternative antihypertensive therapy.

Reference: BNF