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Lithium toxicity — GPhC CRA MCQ

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HardCNS TherapeuticsLithium toxicityGPhC CRA

A 58-year-old woman taking lithium carbonate 400mg twice daily asks for advice after 2 days of vomiting and diarrhoea. She also started ibuprofen for back pain 4 days ago. She feels shaky and unsteady, and her last lithium level was 0.8mmol/L two months ago. What monitoring is required?

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Correct answer: A — Urgent lithium concentration, renal function and electrolytes

Vomiting, diarrhoea, tremor and ataxia in a patient taking lithium suggest possible lithium toxicity. NSAIDs and dehydration can raise lithium concentration, and renal function determines clearance. Urgent lithium level, renal function and electrolytes are needed with medical review. Annual metabolic tests or urine dipstick alone would miss the immediate safety risk.

Reference: BNF Lithium; NICE CKS Bipolar disorder