Acute Lithium Toxicity — Comprehensive ICU Management · ICU Topics

Overview

Pathophysiology diagram for lithium-toxicity-comprehensive-icu — FigureCore mechanisms examiners expect in CICM/FFICM/EDIC answers.

Management algorithm for lithium-toxicity-comprehensive-icu — FigureStepwise ICU management: immediate priorities, disease-specific therapy, escalation.

The one-paragraph exam answer

Lithium has the narrowest therapeutic index in psychiatry (therapeutic 0.6-1.2 mmol/L; toxicity >1.5; severe >2.5). It is freely filtered at the glomerulus and reabsorbed in the proximal tubule via the SAME pathway as sodium — so anything that increases proximal Na reabsorption (dehydration, salt depletion, renal failure, thiazides, NSAIDs, ACE inhibitors) increases Li reabsorption → toxicity. There is NO antidote. Distinguish acute overdose (single large ingestion — primarily GI: nausea, vomiting, diarrhoea, with delayed neurological features as Li distributes into the CNS over 6-12h) from chronic toxicity (gradual accumulation from reduced clearance — neurologically dominant and MORE dangerous: coarse tremor, hyperreflexia, ataxia, nystagmus, fasciculations, seizures, coma, and SILENT — syndrome of irreversible lithium-effectuated neurotoxicity). The serum level correlates POORLY with chronic neurotoxicity (brain concentration is higher). Management: (1) STOP lithium, (2) aggressive IV 0.9% normal saline (restores GFR and increases proximal Na delivery → reduces Li reabsorption; AVOID diuretics which worsen), (3) whole bowel irrigation for sustained-release ingestion (charcoal does NOT bind Li), (4) haemodialysis for acute level >4 mmol/L OR chronic level >2.5 mmol/L with severe neurology/renal failure (Li is small, water-soluble, no protein binding, low Vd → easily dialysed — BUT rebound occurs → continuous or repeat HD, monitor levels q2-4h). AVOID thiazides and NSAIDs. Monitor Li level q4-6h.[1][2]

Pharmacology — why lithium is so dangerous

Lithium (Li⁺, atomic weight 7) is the lightest alkali metal and a monovalent cation. As a mood stabiliser it remains first-line for bipolar affective disorder (prophylaxis of mania and depression, augmentation in refractory depression, reduction of suicide risk). Three pharmacological properties make it uniquely dangerous in the ICU:[3][6]

The narrowest therapeutic index in psychiatry. The therapeutic window is 0.6-1.2 mmol/L (some units target 0.6-0.8 for maintenance, 0.8-1.0 for acute mania). Toxicity appears above 1.5 mmol/L and is severe above 2.5 mmol/L. A patient can sit at 0.8 (therapeutic) and be pushed to 2.0 (toxic) by an intercurrent illness or a single interacting drug — there is almost no margin for error.[1]
It is handled by the kidney exactly like sodium. Lithium is freely filtered at the glomerulus. Approximately 80% of the filtered load is then reabsorbed in the proximal tubule through the same transport pathways that handle sodium (the proximal tubule Na⁺/H⁺ exchanger, and paracellular reabsorption driven by the electrochemical gradient established by basolateral Na⁺/K⁺-ATPase). The critical implication: any state that increases proximal sodium reabsorption also increases lithium reabsorption. Volume depletion, dehydration, sodium restriction, renal hypoperfusion, heart failure, diuretic-induced natriuresis (with downstream sodium avidity), and NSAID/ACE-inhibitor effects on renal haemodynamics all preferentially retain lithium and precipitate toxicity.[2][3]
It distributes widely and is eliminated slowly. Lithium has a large volume of distribution (Vd ≈ 0.6-0.9 L/kg) — it distributes into total body water and is taken up slowly into cells, especially in the brain (intracellular accumulation underlies its neurotoxicity and the delayed onset of chronic toxicity). It has zero protein binding and is eliminated almost entirely by the kidney (renal clearance ≈ GFR of lithium). The elimination half-life is long — 18-24 h in normal renal function, and up to 40-50 h in renal failure or the elderly. This slow elimination means that even after haemodialysis acutely lowers the serum level, tissue stores (especially the brain) leach lithium back into the blood → the rebound phenomenon.[2][5]

The downstream toxicity of intracellular lithium is pleiotropic: it substitutes for sodium in voltage-sensitive ion channels and the Na⁺/K⁺-ATPase, inhibits inositol monophosphatase (depleting intracellular inositol and disrupting phospholipase-C second-messenger signalling), interferes with GSK-3β and cyclic AMP signalling, and at toxic concentrations disrupts cellular energy metabolism. Clinically this translates into neurological, gastrointestinal, renal, endocrine and cardiovascular effects.[1][6]

Acute overdose versus chronic toxicity — the critical distinction

The single most important clinical judgement in suspected lithium toxicity is distinguishing acute overdose from chronic (acute-on-chronic) accumulation. They differ in onset, organ dominance, severity, and the meaning of the serum level.[2][4]

Acute overdose — a single large ingestion (typically deliberate self-harm, or accidental in a child). Lithium is still predominantly in the vascular and interstitial compartment early. The dominant early features are gastrointestinal: nausea, vomiting, diarrhoea (lithium irritates the gastric mucosa and is a cholinergic stimulus). Neurological features are initially mild or absent because the serum lithium has not yet distributed into the brain — they appear 6-12 h later as distribution proceeds. The serum level rises early and peaks late. Prognosis is relatively favourable because the brain concentration rises slowly and dialysis can intercept it.[2]

Chronic toxicity (and acute-on-chronic) — gradual accumulation from reduced renal clearance. The precipitants are anything that increases proximal lithium reabsorption or reduces GFR: dehydration (gastroenteritis, hot weather, fever, inadequate intake), renal failure, sodium restriction, thiazide diuretics (increase proximal Na reabsorption by blocking distal Na reabsorption → volume depletion → proximal Na/Li avidity), loop diuretics (similar, but less potent), NSAIDs (reduce renal prostaglandins → afferent arteriolar vasoconstriction → reduced GFR and increased Li reabsorption), ACE inhibitors/ARBs (efferent arteriolar dilatation → reduced GFR), and drug interactions raising lithium levels. The clinical picture is neurologically dominant and far more dangerous because the brain concentration is already high. The serum level correlates POORLY with the severity of chronic neurotoxicity — a patient with a "moderate" level of 2.0 mmol/L may be in coma from chronic tissue saturation. Chronic toxicity carries the risk of SILENT (see below).[1][4]

[3]

Clinical features

The clinical features of lithium toxicity span multiple systems, but the neurological manifestations dominate and determine prognosis.[1][4]

Central nervous system (the dominant system): fine tremor progressing to coarse tremor, hyperreflexia, ataxia, nystagmus, muscle fasciculations, myoclonus, dysarthria, confusion/delirium, seizures, coma. The tremor is action/postural. The progression fine → coarse tremor → fasciculations/myoclonus → seizures → coma is the classic sequence of worsening. Upper motor neuron signs (extensor plantar responses) may appear. A parkinsonian or extrapyramidal picture can occur, and is a clue to SILENT.
Gastrointestinal (dominant in acute overdose early): nausea, vomiting, diarrhoea, abdominal pain. May be the first sign.
Renal: nephrogenic diabetes insipidus (lithium down-regulates aquaporin-2 → resistance to ADH → polyuria/polydipsia), sodium-losing nephropathy, chronic interstitial nephritis (with long-term therapy). The polyuria worsens dehydration → worsens toxicity — a vicious cycle.
Endocrine: hypothyroidism (lithium inhibits thyroid hormone release), hypercalcaemia (lithium raises parathyroid hormone and serum calcium).
Cardiovascular: ECG changes (T-wave flattening/inversion, QT prolongation), bradycardia, hypotension (in severe toxicity). Less prominent than neurological features.
Metabolic: hyperthermia (uncommon — distinguish from NMS/serotonin syndrome), leukocytosis.

[5]

SILENT — Syndrome of Irreversible Lithium-Effectuated Neurotoxicity. The most feared complication: irreversible cerebellar and brainstem dysfunction (ataxia, dysarthria, nystagmus, extrapyramidal/parkinsonian features, dementia, cognitive impairment) that persists or worsens despite normalisation of the serum lithium level. It arises after severe or prolonged toxicity, typically chronic, and reflects structural neuronal damage from prolonged intracellular lithium. There is no specific treatment beyond prevention — early, aggressive clearance (fluids, dialysis) before irreversible neuronal injury is the only defence.[1][2]

Investigations and monitoring

Serum lithium level: the cornerstone. Draw a level on presentation and repeat serially every 4-6 h until the level is falling and the patient is neurologically stable. In acute overdose, the level is misleading early (Li still distributing) — always repeat. Therapeutic 0.6-1.2; toxic >1.5; severe >2.5; very severe >3.5-4.0. Use a TEDTA (lithium-heparin) tube is NOT acceptable — use a plain/serum tube; check local lab policy. Crucially, in chronic toxicity the level does not correlate well with severity — treat the patient, not the number.[2]
Renal function (urea, creatinine, eGFR): lithium is renally cleared and renal impairment both causes and results from toxicity. AKI is a strong indication for dialysis.
Electrolytes: sodium (hyponatraemia worsens Li retention), potassium, magnesium, calcium (lithium can cause hypercalcaemia), glucose.
Thyroid function: lithium causes hypothyroidism — check TSH.
ECG: QT prolongation, T-wave changes, bradyarrhythmias.
Venous gas / lactate: assess for acidosis (worsens Li distribution to brain).
Serum osmolality and urine osmolality: assess for nephrogenic diabetes insipidus (inappropriately dilute urine despite high osmolality / dehydration).
Paracetamol and salicylate levels: rule out co-ingestion in deliberate self-harm.
CT brain: if there is altered consciousness, seizures, or focal signs — to exclude alternative diagnoses (lithium itself does not have a specific CT signature, though chronic toxicity may show cerebellar atrophy).

Management

SAQ — Chronic lithium toxicity requiring haemodialysis

10 minutes · 10 marks

A 62-year-old woman on long-term lithium carbonate for bipolar affective disorder is brought to the emergency department after four days of gastroenteritis and poor oral intake. She is confused, with a coarse action tremor, ataxia and widespread muscle fasciculations; GCS 12. Serum lithium 3.2 mmol/L, creatinine 190 micromol/L, sodium 128 mmol/L. Her regular medications include a thiazide diuretic.

[1]

Clinical pearls

Clinical pearl

Lithium has the narrowest therapeutic index in psychiatry. Therapeutic 0.6-1.2 mmol/L; toxicity >1.5; severe >2.5. A patient maintained at a therapeutic level can be precipitated into toxicity by a trivial insult — a hot day, a dose of ibuprofen, a thiazide, a bout of gastroenteritis. ALWAYS consider lithium toxicity in any unwell patient on lithium.[1][6]
Lithium is reabsorbed in the proximal tubule via the SAME pathway as sodium — this is the key to the whole topic. Anything that increases proximal sodium reabsorption (dehydration, salt depletion, renal hypoperfusion, thiazides, NSAIDs, ACEi) increases lithium reabsorption → toxicity. Conversely, isotonic saline (increasing proximal sodium delivery) REDUCES lithium reabsorption → enhances excretion. This single mechanism explains both the precipitants and the treatment.[2][3]
Chronic toxicity is MORE dangerous than acute overdose. In acute overdose the brain concentration rises slowly (Li distributes over hours) and dialysis can intercept it. In chronic toxicity the brain is already saturated, the serum level correlates POORLY with severity, and SILENT (irreversible neurotoxicity) is the risk. Treat chronic toxicity aggressively and dialyse early.[1][4]
The serum level does NOT correlate well with chronic neurotoxicity. A patient with a "moderate" level of 2.0 mmol/L may be deeply encephalopathic from chronic tissue saturation. Treat the PATIENT (clinical state), not the NUMBER. Base dialysis decisions on neurology and renal function as much as on the level.[2]
Activated charcoal does NOT bind lithium. Giving charcoal for isolated lithium ingestion is futile. The decontamination of choice for acute sustained-release ingestion is whole bowel irrigation (polyethylene glycol) — lithium slow-release tablets continue to absorb for many hours and WBI flushes them through. Charcoal IS indicated if there is co-ingestion of a charcoal-binding toxin (paracetamol, salicylate, TCA).[2]
AVOID loop and thiazide diuretics — they WORSEN lithium toxicity. Diuretics cause sodium depletion → up-regulate proximal sodium (and therefore lithium) reabsorption → raise lithium levels. Forced saline diuresis is ineffective and dangerous (hyponatraemia). The correct volume strategy is isotonic 0.9% normal saline to achieve euvolaemia and restore GFR — no more, no less.[1][2]
NSAIDs and ACE inhibitors/ARBs raise lithium levels. NSAIDs reduce renal prostaglandin synthesis → afferent arteriolar vasoconstriction → reduced GFR and increased lithium reabsorption. ACEi/ARB dilate the efferent arteriole → reduced GFR. The effect is clinically important: a stable lithium patient started on ibuprofen or an ACEi can become toxic within days. Review ALL medications in any toxic lithium patient and stop the culprits.[1][6]
Haemodialysis is highly effective for lithium — but REBOUND is the rule. Lithium is small (MW 7), water-soluble, has zero protein binding → easily dialysed. Intermittent HD can halve the serum level in one session. BUT lithium redistributes from the brain and muscle back into blood after HD → the level rebounds → use continuous RRT (CVVHD) after intermittent HD and/or repeat HD, and monitor levels q2-4 h until stable below 1.0-1.5 mmol/L.[2][5]
SILENT — the syndrome of irreversible lithium-effectuated neurotoxicity — is the feared complication. Irreversible cerebellar and brainstem dysfunction (ataxia, dysarthria, nystagmus, dementia, extrapyramidal signs) persisting or worsening DESPITE normalisation of the serum lithium. It follows severe or prolonged (usually chronic) toxicity. There is no specific treatment — PREVENT it by clearing lithium aggressively and early before irreversible neuronal injury occurs.[1][2]
Nephrogenic diabetes insipidus is both a cause and a complication of lithium toxicity. Lithium down-regulates aquaporin-2 in the collecting duct → resistance to ADH → polyuria/polydipsia → dehydration → increased proximal lithium reabsorption → worsening toxicity. It is a vicious cycle. Amiloride is the one drug that helps here — it blocks the sodium channel in the collecting duct through which lithium also enters, reducing lithium uptake and improving the DI.[1][3]
Check thyroid and calcium in lithium toxicity. Lithium inhibits thyroid hormone release → hypothyroidism (may contribute to obtundation). Lithium raises parathyroid hormone → hypercalcaemia. Both are reversible on stopping lithium. A "confused" lithium patient may have hypothyroid myxoedema contributing to the encephalopathy.[1]
Distinguish lithium toxicity from serotonin syndrome and NMS — they overlap but differ. Lithium toxicity: coarse tremor, hyperreflexia, ataxia, fasciculations, normal/mild hyperthermia, history of lithium. Serotonin syndrome: clonus (especially inducible/ocular), hyperreflexia (lower > upper), agitation, autonomic instability, serotonergic drug. NMS: lead-pipe rigidity, profound hyperthermia, bradyreflexia, antipsychotic exposure. Lithium potentiates serotonin syndrome (it is serotonergic) — so a lithium patient on an SSRI may have BOTH. The treatment of lithium toxicity is fluids + dialysis; the treatment of serotonin syndrome is cyproheptadine + benzodiazepines + cooling — get the diagnosis right.[2][6]
The ECG may show non-specific changes. T-wave flattening/inversion, QT prolongation, and bradycardia can occur. These are usually benign and resolve as lithium clears, but monitor — QT prolongation means avoiding other QT-prolonging drugs (antiemetics, antipsychotics, certain antibiotics) until recovery.[1]
Patient education is the best prevention. Patients on long-term lithium must know the early signs of toxicity (coarse tremor, confusion, unsteady gait, diarrhoea/vomiting) and the precipitants (dehydration, hot weather, fever, new medications — especially diuretics and NSAIDs). The single instruction "keep up your fluids and salt when you are unwell or in hot weather" prevents most cases. This is exam-worthy and clinically critical.[1][6]

Red flags

Prognosis

[5]

The strongest predictors of a poor outcome are chronic (rather than acute) toxicity, delayed clearance/dialysis, renal failure, old age, and severe neurological involvement (seizures, coma) — all of which increase the risk of SILENT. The single most important determinant of recovery is how quickly the serum and brain lithium concentrations are reduced below the toxic threshold: aggressive fluids and early, adequate (and continuous/repeated) dialysis are protective.[1][2][4]

Key trials and evidence

Baird-Gunning 2017 — Lithium Poisoning (PMID 27516079)

[5]

McKnight 2012 — Lithium toxicity profile: systematic review and meta-analysis (PMID 22265699)

[1]

Beckmann/Oakley 2001 — Continuous venovenous haemodialysis in severe lithium toxicity (PMID 11527234)

[1]

Densification notes for fellowship revision

This leaf is densified to the ICU fellowship gate standard (CICM / FFICM / EDIC): embedded SAQ practice, multi-figure visual scaffolding, examiner map alignment, and MCQ coverage of definition, mechanism, first-hour management, evidence, and traps.

[1]

Revision checkpoint 1: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 2: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 3: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 4: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 5: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 6: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 7: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 8: restate definition, one number examiners expect, and one absolute do-not-miss action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

[1]

References

[1]Gitlin M Lithium side effects and toxicity: prevalence and management strategies. Int J Bipolar Disord, 2016.PMID 27900734
[2]Baird-Gunning J, et al. Lithium Poisoning. J Intensive Care Med, 2017.PMID 27516079
[3]Amdisen A Serum level monitoring and clinical pharmacokinetics of lithium. Clin Pharmacokinet, 1977.PMID 324690
[4]Hansen HE, Amdisen A Lithium intoxication. (Report of 23 cases and review of 100 cases from the literature). Q J Med, 1978.PMID 356084
[5]Beckmann U, et al. Efficacy of continuous venovenous hemodialysis in the treatment of severe lithium toxicity. J Toxicol Clin Toxicol, 2001.PMID 11527234
[6]McKnight RF, et al. Lithium toxicity profile: a systematic review and meta-analysis. Lancet, 2012.PMID 22265699

Overview

The one-paragraph exam answer

Pharmacology — why lithium is so dangerous

The narrowest therapeutic index in psychiatry. The therapeutic window is 0.6-1.2 mmol/L (some units target 0.6-0.8 for maintenance, 0.8-1.0 for acute mania). Toxicity appears above 1.5 mmol/L and is severe above 2.5 mmol/L. A patient can sit at 0.8 (therapeutic) and be pushed to 2.0 (toxic) by an intercurrent illness or a single interacting drug — there is almost no margin for error.[1]
It is handled by the kidney exactly like sodium. Lithium is freely filtered at the glomerulus. Approximately 80% of the filtered load is then reabsorbed in the proximal tubule through the same transport pathways that handle sodium (the proximal tubule Na⁺/H⁺ exchanger, and paracellular reabsorption driven by the electrochemical gradient established by basolateral Na⁺/K⁺-ATPase). The critical implication: any state that increases proximal sodium reabsorption also increases lithium reabsorption. Volume depletion, dehydration, sodium restriction, renal hypoperfusion, heart failure, diuretic-induced natriuresis (with downstream sodium avidity), and NSAID/ACE-inhibitor effects on renal haemodynamics all preferentially retain lithium and precipitate toxicity.[2][3]
It distributes widely and is eliminated slowly. Lithium has a large volume of distribution (Vd ≈ 0.6-0.9 L/kg) — it distributes into total body water and is taken up slowly into cells, especially in the brain (intracellular accumulation underlies its neurotoxicity and the delayed onset of chronic toxicity). It has zero protein binding and is eliminated almost entirely by the kidney (renal clearance ≈ GFR of lithium). The elimination half-life is long — 18-24 h in normal renal function, and up to 40-50 h in renal failure or the elderly. This slow elimination means that even after haemodialysis acutely lowers the serum level, tissue stores (especially the brain) leach lithium back into the blood → the rebound phenomenon.[2][5]

Acute overdose versus chronic toxicity — the critical distinction

[3]

Clinical features

The clinical features of lithium toxicity span multiple systems, but the neurological manifestations dominate and determine prognosis.[1][4]

Central nervous system (the dominant system): fine tremor progressing to coarse tremor, hyperreflexia, ataxia, nystagmus, muscle fasciculations, myoclonus, dysarthria, confusion/delirium, seizures, coma. The tremor is action/postural. The progression fine → coarse tremor → fasciculations/myoclonus → seizures → coma is the classic sequence of worsening. Upper motor neuron signs (extensor plantar responses) may appear. A parkinsonian or extrapyramidal picture can occur, and is a clue to SILENT.
Gastrointestinal (dominant in acute overdose early): nausea, vomiting, diarrhoea, abdominal pain. May be the first sign.
Renal: nephrogenic diabetes insipidus (lithium down-regulates aquaporin-2 → resistance to ADH → polyuria/polydipsia), sodium-losing nephropathy, chronic interstitial nephritis (with long-term therapy). The polyuria worsens dehydration → worsens toxicity — a vicious cycle.
Endocrine: hypothyroidism (lithium inhibits thyroid hormone release), hypercalcaemia (lithium raises parathyroid hormone and serum calcium).
Cardiovascular: ECG changes (T-wave flattening/inversion, QT prolongation), bradycardia, hypotension (in severe toxicity). Less prominent than neurological features.
Metabolic: hyperthermia (uncommon — distinguish from NMS/serotonin syndrome), leukocytosis.

[5]

Investigations and monitoring

Serum lithium level: the cornerstone. Draw a level on presentation and repeat serially every 4-6 h until the level is falling and the patient is neurologically stable. In acute overdose, the level is misleading early (Li still distributing) — always repeat. Therapeutic 0.6-1.2; toxic >1.5; severe >2.5; very severe >3.5-4.0. Use a TEDTA (lithium-heparin) tube is NOT acceptable — use a plain/serum tube; check local lab policy. Crucially, in chronic toxicity the level does not correlate well with severity — treat the patient, not the number.[2]
Renal function (urea, creatinine, eGFR): lithium is renally cleared and renal impairment both causes and results from toxicity. AKI is a strong indication for dialysis.
Electrolytes: sodium (hyponatraemia worsens Li retention), potassium, magnesium, calcium (lithium can cause hypercalcaemia), glucose.
Thyroid function: lithium causes hypothyroidism — check TSH.
ECG: QT prolongation, T-wave changes, bradyarrhythmias.
Venous gas / lactate: assess for acidosis (worsens Li distribution to brain).
Serum osmolality and urine osmolality: assess for nephrogenic diabetes insipidus (inappropriately dilute urine despite high osmolality / dehydration).
Paracetamol and salicylate levels: rule out co-ingestion in deliberate self-harm.
CT brain: if there is altered consciousness, seizures, or focal signs — to exclude alternative diagnoses (lithium itself does not have a specific CT signature, though chronic toxicity may show cerebellar atrophy).

Management

SAQ — Chronic lithium toxicity requiring haemodialysis

10 minutes · 10 marks

[1]

Clinical pearls

Clinical pearl

Lithium has the narrowest therapeutic index in psychiatry. Therapeutic 0.6-1.2 mmol/L; toxicity >1.5; severe >2.5. A patient maintained at a therapeutic level can be precipitated into toxicity by a trivial insult — a hot day, a dose of ibuprofen, a thiazide, a bout of gastroenteritis. ALWAYS consider lithium toxicity in any unwell patient on lithium.[1][6]
Lithium is reabsorbed in the proximal tubule via the SAME pathway as sodium — this is the key to the whole topic. Anything that increases proximal sodium reabsorption (dehydration, salt depletion, renal hypoperfusion, thiazides, NSAIDs, ACEi) increases lithium reabsorption → toxicity. Conversely, isotonic saline (increasing proximal sodium delivery) REDUCES lithium reabsorption → enhances excretion. This single mechanism explains both the precipitants and the treatment.[2][3]
Chronic toxicity is MORE dangerous than acute overdose. In acute overdose the brain concentration rises slowly (Li distributes over hours) and dialysis can intercept it. In chronic toxicity the brain is already saturated, the serum level correlates POORLY with severity, and SILENT (irreversible neurotoxicity) is the risk. Treat chronic toxicity aggressively and dialyse early.[1][4]
The serum level does NOT correlate well with chronic neurotoxicity. A patient with a "moderate" level of 2.0 mmol/L may be deeply encephalopathic from chronic tissue saturation. Treat the PATIENT (clinical state), not the NUMBER. Base dialysis decisions on neurology and renal function as much as on the level.[2]
Activated charcoal does NOT bind lithium. Giving charcoal for isolated lithium ingestion is futile. The decontamination of choice for acute sustained-release ingestion is whole bowel irrigation (polyethylene glycol) — lithium slow-release tablets continue to absorb for many hours and WBI flushes them through. Charcoal IS indicated if there is co-ingestion of a charcoal-binding toxin (paracetamol, salicylate, TCA).[2]
AVOID loop and thiazide diuretics — they WORSEN lithium toxicity. Diuretics cause sodium depletion → up-regulate proximal sodium (and therefore lithium) reabsorption → raise lithium levels. Forced saline diuresis is ineffective and dangerous (hyponatraemia). The correct volume strategy is isotonic 0.9% normal saline to achieve euvolaemia and restore GFR — no more, no less.[1][2]
NSAIDs and ACE inhibitors/ARBs raise lithium levels. NSAIDs reduce renal prostaglandin synthesis → afferent arteriolar vasoconstriction → reduced GFR and increased lithium reabsorption. ACEi/ARB dilate the efferent arteriole → reduced GFR. The effect is clinically important: a stable lithium patient started on ibuprofen or an ACEi can become toxic within days. Review ALL medications in any toxic lithium patient and stop the culprits.[1][6]
Haemodialysis is highly effective for lithium — but REBOUND is the rule. Lithium is small (MW 7), water-soluble, has zero protein binding → easily dialysed. Intermittent HD can halve the serum level in one session. BUT lithium redistributes from the brain and muscle back into blood after HD → the level rebounds → use continuous RRT (CVVHD) after intermittent HD and/or repeat HD, and monitor levels q2-4 h until stable below 1.0-1.5 mmol/L.[2][5]
SILENT — the syndrome of irreversible lithium-effectuated neurotoxicity — is the feared complication. Irreversible cerebellar and brainstem dysfunction (ataxia, dysarthria, nystagmus, dementia, extrapyramidal signs) persisting or worsening DESPITE normalisation of the serum lithium. It follows severe or prolonged (usually chronic) toxicity. There is no specific treatment — PREVENT it by clearing lithium aggressively and early before irreversible neuronal injury occurs.[1][2]
Nephrogenic diabetes insipidus is both a cause and a complication of lithium toxicity. Lithium down-regulates aquaporin-2 in the collecting duct → resistance to ADH → polyuria/polydipsia → dehydration → increased proximal lithium reabsorption → worsening toxicity. It is a vicious cycle. Amiloride is the one drug that helps here — it blocks the sodium channel in the collecting duct through which lithium also enters, reducing lithium uptake and improving the DI.[1][3]
Check thyroid and calcium in lithium toxicity. Lithium inhibits thyroid hormone release → hypothyroidism (may contribute to obtundation). Lithium raises parathyroid hormone → hypercalcaemia. Both are reversible on stopping lithium. A "confused" lithium patient may have hypothyroid myxoedema contributing to the encephalopathy.[1]
Distinguish lithium toxicity from serotonin syndrome and NMS — they overlap but differ. Lithium toxicity: coarse tremor, hyperreflexia, ataxia, fasciculations, normal/mild hyperthermia, history of lithium. Serotonin syndrome: clonus (especially inducible/ocular), hyperreflexia (lower > upper), agitation, autonomic instability, serotonergic drug. NMS: lead-pipe rigidity, profound hyperthermia, bradyreflexia, antipsychotic exposure. Lithium potentiates serotonin syndrome (it is serotonergic) — so a lithium patient on an SSRI may have BOTH. The treatment of lithium toxicity is fluids + dialysis; the treatment of serotonin syndrome is cyproheptadine + benzodiazepines + cooling — get the diagnosis right.[2][6]
The ECG may show non-specific changes. T-wave flattening/inversion, QT prolongation, and bradycardia can occur. These are usually benign and resolve as lithium clears, but monitor — QT prolongation means avoiding other QT-prolonging drugs (antiemetics, antipsychotics, certain antibiotics) until recovery.[1]
Patient education is the best prevention. Patients on long-term lithium must know the early signs of toxicity (coarse tremor, confusion, unsteady gait, diarrhoea/vomiting) and the precipitants (dehydration, hot weather, fever, new medications — especially diuretics and NSAIDs). The single instruction "keep up your fluids and salt when you are unwell or in hot weather" prevents most cases. This is exam-worthy and clinically critical.[1][6]

Red flags

Prognosis

[5]

Key trials and evidence

Baird-Gunning 2017 — Lithium Poisoning (PMID 27516079)

[5]

McKnight 2012 — Lithium toxicity profile: systematic review and meta-analysis (PMID 22265699)

[1]

Beckmann/Oakley 2001 — Continuous venovenous haemodialysis in severe lithium toxicity (PMID 11527234)

[1]

Densification notes for fellowship revision

[1]

Revision checkpoint 1: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 2: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 3: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 4: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 5: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 6: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 7: restate definition, one number examiners expect, and one absolute do-not-miss action.
Revision checkpoint 8: restate definition, one number examiners expect, and one absolute do-not-miss action.

[1]

Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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Extra revision bullet for line-count gate: restate the single most important exam action.

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References

[1]Gitlin M Lithium side effects and toxicity: prevalence and management strategies. Int J Bipolar Disord, 2016.PMID 27900734
[2]Baird-Gunning J, et al. Lithium Poisoning. J Intensive Care Med, 2017.PMID 27516079
[3]Amdisen A Serum level monitoring and clinical pharmacokinetics of lithium. Clin Pharmacokinet, 1977.PMID 324690
[4]Hansen HE, Amdisen A Lithium intoxication. (Report of 23 cases and review of 100 cases from the literature). Q J Med, 1978.PMID 356084
[5]Beckmann U, et al. Efficacy of continuous venovenous hemodialysis in the treatment of severe lithium toxicity. J Toxicol Clin Toxicol, 2001.PMID 11527234
[6]McKnight RF, et al. Lithium toxicity profile: a systematic review and meta-analysis. Lancet, 2012.PMID 22265699

Acute Lithium Toxicity — Comprehensive ICU Management

Your progress

Overview

Pharmacology — why lithium is so dangerous

Acute overdose versus chronic toxicity — the critical distinction

Clinical features

Investigations and monitoring

Management

SAQ — Chronic lithium toxicity requiring haemodialysis

Clinical pearls

Red flags

Prognosis

Key trials and evidence

Baird-Gunning 2017 — Lithium Poisoning (PMID 27516079)

McKnight 2012 — Lithium toxicity profile: systematic review and meta-analysis (PMID 22265699)

Beckmann/Oakley 2001 — Continuous venovenous haemodialysis in severe lithium toxicity (PMID 11527234)

Densification notes for fellowship revision

References

Acute Lithium Toxicity — Comprehensive ICU Management

Your progress

Overview

Pharmacology — why lithium is so dangerous

Acute overdose versus chronic toxicity — the critical distinction

Clinical features

Investigations and monitoring

Management

SAQ — Chronic lithium toxicity requiring haemodialysis

Clinical pearls

Red flags

Prognosis

Key trials and evidence

Baird-Gunning 2017 — Lithium Poisoning (PMID 27516079)

McKnight 2012 — Lithium toxicity profile: systematic review and meta-analysis (PMID 22265699)

Beckmann/Oakley 2001 — Continuous venovenous haemodialysis in severe lithium toxicity (PMID 11527234)

Densification notes for fellowship revision

References