What is the management approach for suspected lithium toxicity?

Management of Suspected Lithium Toxicity

In suspected lithium toxicity, immediate discontinuation of lithium, assessment of serum lithium levels, and supportive care are essential first steps, with hemodialysis indicated for severe toxicity (levels >3.5 mEq/L), neurological symptoms, or renal failure.

Initial Assessment and Stabilization

Clinical Evaluation

• Assess for symptoms of lithium toxicity:
  • Mild to moderate toxicity: Tremor, nausea, diarrhea, blurred vision, lethargy, muscle weakness
  • Severe toxicity: Confusion, seizures, coma, cardiac arrhythmias, hypotension

Laboratory Assessment

• Obtain immediate serum lithium level
  • Therapeutic range: 0.4-1.0 mEq/L
  • Toxic range: >1.5 mEq/L
  • Severe toxicity: >2.5 mEq/L
• Important pitfall: Ensure blood is NOT collected in lithium heparin tubes which can cause falsely elevated results 1
• Additional tests:
  • Complete blood count
  • Comprehensive metabolic panel (especially renal function)
  • Thyroid function tests (thyrotoxicosis can precipitate lithium toxicity) 2
  • ECG (assess for arrhythmias)

Management Algorithm

1. Mild Toxicity (Lithium level 1.5-2.5 mEq/L with minimal symptoms)

• Discontinue lithium immediately
• Ensure adequate hydration with IV fluids
• Monitor lithium levels every 4-6 hours until declining
• Monitor vital signs and neurological status

2. Moderate Toxicity (Lithium level 2.5-3.5 mEq/L or significant symptoms)

• Discontinue lithium immediately
• Aggressive IV fluid resuscitation with normal saline
• Consider gastric lavage if recent ingestion
• Correct electrolyte imbalances
• Monitor cardiac function continuously
• Consider nephrology consultation for possible dialysis

3. Severe Toxicity (Lithium level >3.5 mEq/L or severe neurological symptoms)

• Immediate hemodialysis is indicated 3
• Consider hemodialysis followed by continuous veno-venous hemodiafiltration (CVVHDF) to prevent rebound increases in lithium levels 4
• Lithium clearance with hemodialysis (173 ml/min) is significantly higher than with CVVHDF (61 ml/min), but the combination prevents rebound 4

Indications for Hemodialysis

Hemodialysis should be initiated when any of the following are present:

• Serum lithium level >3.5 mEq/L
• Severe neurological symptoms regardless of lithium level
• Significant renal impairment limiting lithium excretion
• Hemodynamic instability
• Deteriorating mental status despite supportive care

Special Considerations

Precipitating Factors to Address

• Dehydration (common trigger)
• Medication interactions:
  • NSAIDs should be avoided in patients taking lithium 5
  • Diuretics can increase lithium levels
• Thyroid dysfunction (can alter lithium excretion) 2
• Renal impairment

Monitoring During Recovery

• Continue monitoring lithium levels until stable in therapeutic range
• Assess neurological status regularly
• Monitor renal function
• Evaluate for permanent neurological sequelae

Follow-up Care

• Reassess need for lithium therapy
• If continuing lithium:
  • Adjust dosage based on renal function
  • Monitor lithium levels every 6 months or with any change in clinical status 5
  • Monitor GFR, electrolytes, and lithium levels more frequently if dose changes or patient becomes acutely ill 5
  • Maintain adequate hydration, especially during intercurrent illness

Conclusion

Lithium toxicity requires prompt recognition and intervention due to its narrow therapeutic window. The management approach should be based on severity of toxicity, with hemodialysis being the definitive treatment for severe cases. Careful monitoring and addressing precipitating factors are essential to prevent recurrence.