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Lithium and Breastfeeding — MRCPsych Paper B MCQ

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HardPerinatal PsychiatryLithium and BreastfeedingMRCPsych Paper B

A woman with bipolar I disorder has remained well on lithium after several severe previous relapses. She gives birth at term to a healthy infant and wishes to breastfeed. Local services could provide infant biochemical monitoring if required. Which statement best reflects current UK guidance on lithium and breastfeeding?

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

Reveal the answer and explanation

Correct answer: C — Advise that breastfeeding is generally not recommended during lithium treatment; if chosen after specialist assessment, arrange close infant clinical and biochemical monitoring.

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

B is correct. NICE advises that women taking lithium should generally not be encouraged to breastfeed because lithium concentrations in breast milk may be high and can cause infant toxicity. The UK product information similarly recommends bottle-feeding. This is not a reason to stop an effective maternal treatment abruptly, particularly where relapse risk is high. If, after specialist perinatal risk–benefit assessment, the woman chooses to breastfeed, the infant requires close clinical observation and monitoring of lithium concentration, renal function and thyroid function; dehydration or intercurrent illness increases toxicity risk. A is unsafe because observation alone is insufficient. C is incorrect because changing formulation does not remove lithium exposure. D describes no recognised safe 48-hour threshold. E reverses the pharmacology: milk transfer can be substantial, while neonatal renal clearance is limited.

Reference: National Institute for Health and Care Excellence. Antenatal and postnatal mental health: clinical management and service guidance (CG192), recommendations 1.4.34 and 1.9.8. 2014, amended 2020. https://www.nice.org.uk/guidance/cg192/chapter/Recommendations