Lithium and ECT flashcards
13 high-yield MRCP Part 1 cards from the Intellect Medicos Psychiatry course. Try to answer each question before you open it — then study them properly with spaced repetition, which brings each card back just before you would forget it.
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What serum lithium level should be targeted when starting lithium for bipolar disorder?
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0.6–0.8 mmol/L (specialists may aim for 0.8–1.0 mmol/L if the response is sub-optimal).
Why? Lithium has a narrow therapeutic index, so small rises above the range can cause toxicity.
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When should a blood sample for serum lithium be taken in relation to the last dose?
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12 hours after the last dose.
Why? Reference ranges are based on 12-hour post-dose levels; samples taken earlier will read falsely high.
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Name three drug classes that commonly raise serum lithium levels.
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Thiazide (and other) diuretics, ACE inhibitors / ARBs, and NSAIDs.
Why? All reduce renal lithium clearance. Dehydration and renal impairment do the same.
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A woman on long-term lithium was started on bendroflumethiazide 2 weeks ago. She now has vomiting, a coarse tremor, ataxia, slurred speech and brisk reflexes. What is the first-line investigation?
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An urgent serum lithium level (with U&Es and creatinine).
Why? These are features of lithium toxicity, here triggered by a thiazide reducing lithium clearance.
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What is the treatment of choice for severe lithium toxicity (e.g. neurological features or renal failure)?
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Haemodialysis.
Why? Lithium is a small, water-soluble, non-protein-bound ion, so dialysis removes it well. Mild–moderate toxicity is treated by stopping lithium and giving IV fluids.
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Long-term lithium can cause polyuria and thirst from ______; its commonest endocrine side effect, often with a goitre, is hypothyroidism.
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nephrogenic diabetes insipidus
Why? Lithium blocks the renal response to ADH and inhibits thyroid hormone release, which is why renal and thyroid function are monitored.
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Long-term lithium can cause polyuria and thirst from nephrogenic diabetes insipidus; its commonest endocrine side effect, often with a goitre, is ______.
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hypothyroidism
Why? Lithium blocks the renal response to ADH and inhibits thyroid hormone release, which is why renal and thyroid function are monitored.
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What is classically cited as the absolute contraindication to ECT?
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Raised intracranial pressure.
Why? ECT causes a transient rise in cerebral blood flow and intracranial pressure, which could precipitate herniation.
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Apart from the serum lithium level, which blood tests are checked before starting lithium and then at least every 6 months?
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Renal function (U&E, eGFR), thyroid function and calcium. Weight or BMI is also monitored.
Why? Lithium can cause renal impairment and nephrogenic diabetes insipidus, hypothyroidism, and hyperparathyroidism with hypercalcaemia.
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Which congenital heart defect is classically linked with lithium exposure in the first trimester?
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Ebstein's anomaly (downward displacement of the tricuspid valve).
Why? The BNF advises avoiding lithium if possible in the first trimester because of the risk of cardiac malformations. The absolute risk is lower than older data suggested, so decisions are made with a specialist.
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Which parathyroid and calcium disturbance can long-term lithium cause?
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Hyperparathyroidism with hypercalcaemia.
Why? Lithium raises the set-point at which calcium suppresses PTH. This is why calcium is checked at baseline and every 6 months.
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Why does sodium depletion (vomiting, a low-salt diet or dehydration) raise serum lithium?
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The kidney handles lithium like sodium; when sodium is low, the proximal tubule reabsorbs more sodium and lithium with it.
Why? Patients are told to keep up fluid intake and avoid sudden changes in salt intake, and to seek help if they become dehydrated.
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When does NICE recommend considering ECT for depression?
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Severe depression when a rapid response is needed (e.g. life-threatening because the person is not eating or drinking), when other treatments have failed, or when the person prefers it after past benefit.
Why? ECT works faster than drugs in severe depression. It is also used for severe or treatment-resistant mania and catatonia.