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Lithium and CKD Stage 3 — MRCPsych Paper B MCQ

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HardMood DisordersLithium and CKD Stage 3MRCPsych Paper B

A 55-year-old man with bipolar disorder has remained well for several years on lithium 800 mg daily. His plasma lithium level is 0.7 mmol/L and he has no symptoms of toxicity. His eGFR measurements over the past 12 months have fallen from 58 to 51 and then 45 mL/min/1.73 m². Which management approach best accords with NICE CG185?

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Correct answer: E — Increase lithium-level and renal-function monitoring, assess the rate of renal deterioration, and review continuation with renal and bipolar specialist advice if needed

Explanation lettering: D = shown as B · E = shown as D · B = shown as E

B is correct. The serial eGFR decline over three measurements activates NICE CG185 recommendation 1.10.22: lithium levels and renal function should be monitored more frequently and the rate of deterioration assessed. Whether lithium should continue requires an individualised benefit–risk review considering its effectiveness, the degree of renal impairment, and other renal and cardiovascular risk factors; renal and bipolar specialist advice should be sought if needed. CKD G3a is not, by itself, an instruction to stop lithium or substitute valproate, so A and D are inappropriate. C ignores the progressive renal decline despite a therapeutic lithium level. E is incorrect because 0.7 mmol/L is within the usual maintenance target, and increasing exposure may increase toxicity risk.

Reference: National Institute for Health and Care Excellence. Bipolar disorder: assessment and management (CG185), recommendations 1.10.22–1.10.23. Published 2014; updated 2025. https://www.nice.org.uk/guidance/cg185/chapter/Recommendations