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Chronic lithium toxicity with acute kidney injury and marked neurological features — MRCEM SBA MCQ

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HardMental health and behavioural emergenciesChronic lithium toxicity with acute kidney injury and marked neurological featuresMRCEM SBA

A 63-year-old man with bipolar disorder has taken a stable dose of lithium for several years. After three days of vomiting and poor oral intake, he has become increasingly confused and unable to walk. He has also been taking ibuprofen for knee pain. His partner confirms that he has taken no extra lithium. He is drowsy but rousable, with a coarse tremor, dysarthria and marked truncal ataxia. His creatinine is 198 µmol/L, compared with 84 µmol/L at his last review, and his serum lithium concentration is 1.7 mmol/L. Which management and disposition plan is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — Stop lithium, give intravenous isotonic saline and admit medically with urgent dialysis assessment.

This is **chronic lithium accumulation with marked neurological toxicity**. Fluid loss, poor intake and ibuprofen use increase the risk of toxicity, while the acute kidney injury impairs lithium elimination. Dysarthria and severe truncal ataxia are cerebellar signs; the serum concentration of 1.7 mmol/L must not delay escalation. UK product information advises considering haemodialysis in patients with marked neurological features or severe symptoms regardless of the measured concentration, with advice from the local poisons service. Stop lithium, restore fluid and electrolyte balance, monitor renal function, ECG and serial lithium concentrations, and arrange urgent renal assessment while admitting him for medical care. ([medicines.org.uk](https://www.medicines.org.uk/emc/product/10828/smpc)) **A** includes essential supportive treatment but omits timely dialysis assessment. **B** applies an overdose decontamination approach to chronic accumulation; activated charcoal does not adsorb lithium. **D** makes a rising concentration the trigger, although the existing neurological findings already justify assessment. **E** recognises the need for escalation but substitutes furosemide for fluid replacement; diuretics should not be used to treat lithium poisoning. ([medicines.org.uk](https://www.medicines.org.uk/emc/product/10828/smpc))

Reference: Lithium Carbonate Essential Pharma 250 mg film-coated tablets: Summary of Product Characteristics (26 November 2024) — https://www.medicines.org.uk/emc/product/10828/smpc NHS Specialist Pharmacy Service: Lithium monitoring (6 December 2024) — https://sps.nhs.uk/monitorings/lithium-monitoring/