Lithium



Background

  • Primarily used for uni / bipolar depression
  • Narrow therapeutic range (0.4 - 1.0 mmol/). Toxicity at 2.0 mmol/l
  • Acute toxicity
    • Thirst, polyuria, tremor, dysarthria, ataxia, arrhythmia ± coma
  • Chronic toxicity
    • Acne, hypothyroidism, alopecia & psoriasis, diabetes insipidus

Toxicity

  • Readily absorbed in GI tract over 4 - 6 hours post overdose
  • Widely distributed
  • Not protein bound - circulates as simple cation
  • Renal excretion
  • Elimination t1/2 usually 24 hours but dependant upon renal function
  • Acute toxicity usually occurs on background of chronic with altered metabolism eg dehydration

Management

  • Admit all with symptoms of toxicity or levels > 2mmol/l
  • Supportive management - A, B, C with correction fluid / electrolyte imbalance
  • Avoid charcoal
  • GI Tract decontamination unhelpful
  • Whole bowel irrigation MAY be useful (no evidence either way) if sustained release preparation ingested
  • Avoid forced diuresis
  • Haemodialysis (repeated to treat rebound post treatment levels) very effective
  • Haemodialysis indications (severe / life threatening overdose)

Beware

  • Progressive clinical deterioration
  • Life threatening arrhythmias
  • Coma, seizures, respiratory failure
  • Rising serum lithium concentration
  • Impaired renal fxn
  • Serum Li conc > 4 mmol/l in acute on chronic toxicity
  • Serum Li conc > 8 mmol/l in acute toxicity


Content by - Dr Íomhar O' Sullivan. Last rev24/03/24e --> -->->--> -->.