What is the management of lithium overdose?

Management of Lithium Overdose

The management of lithium overdose requires immediate discontinuation of lithium, supportive care, and hemodialysis for severe cases with high lithium levels (>3.5 mEq/L) or significant clinical toxicity. 1

Types of Lithium Overdose

• Acute overdose: Single large ingestion in lithium-naïve patients
• Acute-on-chronic overdose: Acute ingestion in patients on maintenance therapy
• Chronic overdose: Gradual accumulation due to decreased clearance or medication interactions

Initial Assessment and Management

1. Assess severity:

   • Measure serum lithium level immediately
   • Toxic levels are close to therapeutic levels (therapeutic: 0.6-1.0 mM)
   • Mild toxicity: 1.5-2.5 mEq/L
   • Moderate toxicity: 2.5-3.5 mEq/L
   • Severe toxicity: >3.5 mEq/L 2

2. Immediate interventions:

   • Discontinue lithium administration
   • Perform gastric lavage for recent ingestions
   • Correct fluid and electrolyte imbalances
   • Monitor vital signs and neurological status 1

Indications for Hemodialysis

Hemodialysis is the most effective method for lithium removal in severe cases. Consider hemodialysis for:

• Lithium level >3.5 mEq/L
• Severe neurological symptoms regardless of level
• Significant renal impairment
• Hemodynamic instability
• Failure to respond to supportive measures 2

Monitoring

• Serial lithium levels: Monitor every 2-4 hours initially as levels may rise unexpectedly
• Watch for delayed reintoxication: Secondary elevation in lithium levels can occur 24-48 hours after initial treatment, particularly with extended-release formulations or anticholinergic co-ingestion 3
• Neurological assessment: Monitor for signs of neurotoxicity (confusion, tremor, hyperreflexia, seizures, coma)
• Renal function: Monitor creatinine, BUN, and urine output

Clinical Manifestations to Monitor

• Neurological: Tremor, confusion, lethargy, hyperreflexia, seizures, coma
• Gastrointestinal: Nausea, vomiting, diarrhea
• Cardiovascular: Bradycardia, hypotension, QT prolongation
• Renal: Polyuria, decreased concentrating ability, acute kidney injury 4

Special Considerations

• Cardiac complications: Though uncommon (5.7% of cases), bradycardia and conduction abnormalities may occur, particularly in chronic lithium toxicity 5
• Delayed neurotoxicity: Can develop even after lithium levels normalize; do not restart lithium immediately after levels normalize 6
• Renal replacement therapy: Continuous venovenous hemodialysis may be preferred for hemodynamically unstable patients 2

Post-Acute Management

1. Do not restart lithium immediately after an overdose, even if levels have normalized, due to risk of delayed neurotoxicity 6
2. Evaluate for persistent neurological sequelae
3. Reassess need for lithium therapy and consider alternative mood stabilizers if appropriate
4. Patient education on recognizing early symptoms of lithium toxicity and importance of regular monitoring 1

Prognosis

• Mortality is rare (0.8%) with appropriate management 5
• Most patients recover completely with prompt intervention
• Chronic lithium toxicity carries higher risk of permanent neurological sequelae than acute overdose

Remember that the toxic threshold for lithium is close to therapeutic levels, making careful monitoring essential for all patients on lithium therapy.