Lithium

Lithium toxicity may be either:

Epidemiology and Risk Factors

Pathophysiology

Aetiology

Clinical Features

Gastrointestinal:

  • Nausea
  • Vomiting
  • Diarrhoea
  • Abdominal pain

Neurological:

  • Mild
    Rare that acute overdose would progress further, provided adequate elimination.
    • Tremor
    • Hyperreflexia
    • Agitation
    • Weakness
    • Ataxia
  • Moderate
    • Stupor
    • Rigidity
    • Hypertonia
    • ↓ BP
  • Severe
    Very rare, other toxins should be considered if these features are present.
    • Coma
    • Seizure
    • Myoclonus

Diagnostic Approach and DDx

Investigations

Bedside:

  • ABG
    • Low-anion gap metabolic acidosis
  • ECG
  • BSL

Three drugs cause a low-anion gap metabolic acidosis:

  • Lithium
  • Bromide
  • Iodine

Laboratory:

  • Blood
    • Lithium level
      • On arrival for chronic toxicity, and then Q4-6 hourly
      • 6 hours post-ingestion for acute overdose, and then Q4-6 hourly
    • Paracetamol level
    • Thyroid

Imaging:

Other:

Management

Resuscitation:

  • C
    • Fluid resuscitation

Specific therapy:

Lithium behaves similarly to sodium in the kidney, and so is reabsorbed in hypovolaemic states and has ↓ clearance in renal failure.

  • Pharmacological
    • Fluid resuscitation
  • Procedural
    • Whole bowel irrigation
      Can be considered.
    • RRT
      • Severe toxicity
      • Acute: Serum lithium >7.5mmol/L
      • Chronic: Serum lithium >4mmol/L
  • Physical

Supportive care:

Disposition:

Preventative:

Marginal and Ineffective Therapies

  • Thiazide diuretics
    May precipitate acute toxicity.
  • Phenytoin
    Should not be used for seizure control.

Anaesthetic Considerations

Complications

Prognosis

Key Studies

References

  1. Bersten, A. D., & Handy, J. M. (2018). Oh’s Intensive Care Manual. Elsevier Gezondheidszorg.