Lithium Toxicity

Summary

Lithium toxicity occurs when lithium levels rise above 1.5. Risk factors for developing lithium toxicity include dehydration, NSAIDs, kidney damage, hyponatremia, and use of thiazide diuretics.

Symptoms of lithium toxicity can affect multiple body systems. Renal symptoms include severe polyuria and severe polydipsia, as the kidneys lose their ability to concentrate urine, leading to dehydration and excessive thirst. Gastrointestinal symptoms may include nausea, vomiting, and diarrhea, which often appear early in the course of toxicity. Neurological symptoms include coarse tremors, ataxia , slurred speech, confusion, and drowsiness. In more severe cases, seizures may occur. Tinnitus, or ringing in the ears, can also appear as lithium levels rise and affect the auditory system.

Key Points

• Lithium Toxicity
  • Lithium Levels
    • Toxic above 1.5 mEq/L
      • Symptoms of toxicity often start to appear with lithium levels above 1.5 mEq/L, although exact levels and symptoms will differ with each patient
  • Risk Factors for Toxicity
    • Hyponatremia
      • Sodium level below 135 mEq/L puts patient at higher risk of developing lithium toxicity
    • Dehydration
      • Increased fluid loss (diarrhea, vomiting, polyuria) puts patient at risk of lithium toxicity
      • Stress the importance of maintaining adequate fluid intake
    • NSAIDs
      • Instruct patient to avoid over-the-counter NSAIDS, such as ibuprofen
    • Thiazide Diuretics
      • Thiazide diuretics decrease the excretion of lithium, leading to lithium toxicity in the blood
    • Kidney damage (renal dysfunction)
      • Lithium is excreted through the kidney, so impaired kidneys means the drug isn’t leaving the body as quickly as it should, and can lead to toxicity
      • Use with caution in patients with known kidney issues
  • Symptoms of Toxicity
    • Nausea/vomiting
      • Persistent nausea and vomiting can be an early sign of lithium toxicity
    • Diarrhea
    • Severe polyuria
    • Severe thirst (polydipsia)
    • Ataxia
      • Loss of coordination that can affect patient’s balance, muscle control, and ability to walk
    • Confusion
      • Report signs of altered level of consciousness to the provider
    • Slurred speech
    • Drowsiness
    • Tinnitus
      • Ringing in the ears
    • Coarse tremors
      • Although fine tremors are an expected side effect of lithium, tremors that are course can indicate toxicity
      • Teach patients to monitor the severity of tremors
    • Seizures
      • A late sign of toxicity