What are the symptoms and treatment of lithium toxicity?

Symptoms and Treatment of Lithium Toxicity

Lithium toxicity is a serious medical condition with symptoms that primarily affect the central nervous system, and treatment should focus on drug discontinuation, supportive care, and hemodialysis for severe cases with high serum lithium levels or significant neurological symptoms.

Symptoms of Lithium Toxicity

Lithium toxicity presents with a spectrum of symptoms that vary based on whether the toxicity is acute, acute-on-chronic, or chronic:

Neurological Symptoms (Most Common)

• Early symptoms:

  • Tremor
  • Lethargy
  • Confusion
  • Ataxia (impaired coordination)
  • Muscle weakness
  • Slurred speech

• Severe symptoms:

  • Altered mental status/delirium
  • Seizures
  • Coma
  • Persistent cerebellar deficits 1

Gastrointestinal Symptoms

• Nausea
• Vomiting
• Diarrhea

Cardiovascular Symptoms

• Dysrhythmias
• ECG changes
• Hypotension (in severe cases)
• Rarely: cardiomyopathy and myocardial infarction 2

Renal Symptoms

• Polyuria-polydipsia (excessive thirst and urination)
• Nephrogenic diabetes insipidus 1

Types of Lithium Toxicity

• Acute toxicity: Usually from intentional or accidental overdose; often has milder symptoms despite high serum levels 3
• Chronic toxicity: Most common form; usually unintentional and occurs when lithium intake exceeds elimination, often due to impaired kidney function, volume depletion, or drug interactions 1
• Acute-on-chronic toxicity: Occurs in patients on maintenance therapy who take an additional acute overdose

Risk Factors for Lithium Toxicity

• Dehydration
• Renal insufficiency
• Drug interactions (NSAIDs, diuretics, ACE inhibitors)
• Advanced age
• Changes in sodium intake
• Non-adherence to monitoring 4

Treatment of Lithium Toxicity

Immediate Management

1. Discontinue lithium immediately upon suspicion of toxicity 5
2. Assess severity based on:
   • Serum lithium level
   • Clinical symptoms
   • Type of toxicity (acute vs. chronic)

Supportive Care

• Fluid and electrolyte management: Correct dehydration and electrolyte imbalances 5
• Airway management: Ensure adequate respiration in severe cases
• Gastric lavage: Consider for acute ingestions if presenting early 5

Specific Treatments

• Mild to moderate toxicity (minimal symptoms, levels <3.5 mEq/L):

  • IV fluids to enhance renal elimination
  • Close monitoring of lithium levels and symptoms
  • Supportive care

• Severe toxicity (significant neurological symptoms or levels ≥3.5 mEq/L):

  • Hemodialysis is the treatment of choice 6
  • Indications for hemodialysis include:
    • Severe neurological symptoms regardless of level
    • Serum lithium level ≥3.5 mEq/L in chronic toxicity
    • Significant renal impairment limiting lithium excretion
    • Failure to respond to supportive measures 1

Special Considerations

• Patients with chronic toxicity typically have more severe symptoms than those with acute toxicity at the same serum lithium level 3
• Patients with acute overdose may have high serum levels but milder symptoms and may not always require hemodialysis 3
• No specific antidote exists for lithium poisoning 5

Monitoring During Treatment

• Frequent serum lithium level measurements
• Renal function tests
• Electrolytes
• Continuous cardiac monitoring in severe cases
• Neurological assessments

Prognosis

• Most patients recover completely with appropriate treatment
• Some patients may develop persistent neurological deficits, particularly cerebellar dysfunction
• Mortality is low with appropriate treatment 1

Prevention of Recurrence

• Regular monitoring of lithium levels (initially twice weekly during acute phase, then every 3-6 months when stable) 4
• Concurrent monitoring of renal function, thyroid function, and urinalysis every 3-6 months 4
• Patient education about early symptoms of toxicity and when to seek medical attention
• Awareness of drug interactions and factors that can alter lithium clearance