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CDHB

Lithium

Acute lithium overdosage is more benign than chronic toxicity

• Well absorbed orally. Eliminated solely by the kidneys.
• Activated charcoal doesn't bind lithium.
• In acute overdosage with normal renal function <25 g is benign (even if on therapeutic lithium already, i.e., acute on chronic overdose).
• Coma is very unusual with acute lithium overdose.
• Nausea, vomiting, pain and diarrhoea may occur due to GI irritation.
• Correct dehydration. Ensure renal function is normal.
• Patients with no neurotoxicity, good urine output and serum lithium of <2.5 mmol/L do not require further medical care.

Chronic lithium toxicity

• Lithium neurotoxicity usually due to impaired lithium excretion.
• Much higher risk of serious toxicity and permanent neurological damage.
• Lithium excretion can be impaired by dehydration, NSAIDs, ACE inhibitors, or diuretics.
• Consider chronic toxicity in anyone on therapeutic lithium who presents with neurological symptoms or decreased consciousness.
• Hansen and Amidsen Grading:
  • Grade 1 Tremor, hyperreflexia, weakness, ataxia.
  • Grade 2 Stupor, rigidity, hypotonia, hypotension.
  • Grade 3 Coma, convulsions.
• Serum levels may not correlate with CSF levels or clinical toxicity.
• Management requires careful attention to correct water and sodium deficits.
• Haemodialysis may be useful if deteriorating with significant symptoms and level >2.5 mmol/L or if urine output inadequate.
• Significant toxicity will require ICU care.

Topic Code: 1599