Lithium toxicity

Overview of lithium toxicity in medical context

Lithium toxicity is a condition that occurs when there is an excessive amount of lithium in the body. Lithium is a medication commonly used to treat bipolar disorder and other mood disorders. While it is effective in managing these conditions, it has a narrow therapeutic index, meaning that the difference between a therapeutic dose and a toxic dose is small.

Pathophysiology

Lithium affects the central nervous system and kidneys. It is primarily excreted by the kidneys, and any condition that affects renal function can increase the risk of lithium toxicity. The drug works by altering sodium transport in nerve and muscle cells and affecting a shift toward intraneuronal metabolism of catecholamines.

Causes

Lithium toxicity can occur due to several reasons:

• Acute overdose: Ingestion of a large amount of lithium in a short period.
• Chronic accumulation: Occurs when the body is unable to excrete lithium efficiently, often due to renal impairment or drug interactions.
• Dehydration: Can lead to increased lithium levels as the body retains lithium in an attempt to conserve sodium and water.

Symptoms

Symptoms of lithium toxicity can vary depending on the severity and duration of exposure. They are generally categorized into mild, moderate, and severe:

Mild toxicity

• Nausea and vomiting
• Diarrhea
• Drowsiness
• Muscle weakness

Moderate toxicity

• Confusion
• Ataxia
• Blurred vision
• Tinnitus

Severe toxicity

• Seizures
• Coma
• Renal failure
• Cardiac arrhythmias

Diagnosis

Diagnosis of lithium toxicity is based on clinical presentation and measurement of serum lithium levels. Levels above 1.5 mEq/L are generally considered toxic, but symptoms can occur at lower levels in some individuals.

Treatment

Treatment of lithium toxicity involves:

• Discontinuation of lithium: Immediate cessation of lithium intake.
• Hydration: Intravenous fluids to enhance renal excretion of lithium.
• Hemodialysis: In severe cases, especially when renal function is compromised, hemodialysis may be necessary to remove lithium from the bloodstream.

Prevention

Preventing lithium toxicity involves regular monitoring of serum lithium levels, maintaining adequate hydration, and adjusting doses in response to changes in renal function or concurrent medications.

Related pages

• Bipolar disorder
• Renal function
• Central nervous system

Lithium carbonate 300 mg tablets