Lithium toxicity

Learning objectives

Lithium is a very powerful, antimanic medication with a narrow therapeutic index
Excessive intake or impaired excretion can result in lithium accumulation
Decreased excretion may occur as a result of dehydration such as from vomiting or diarrhea, a low sodium diet, or from kidney problems
Co-ingestants can increase the risk of lithium toxicity
- NSAIDs
- Indomethacin
- Selective COX-2inhiitors
- Acetaminophen
- Metronidazole
- Calcium channel blockers
- ACE inhibitors
- Diuretics
Acute toxicity: lithium overdose in a patient who does not regularly take lithium
Acute-on-chronic toxicity: acute overdose in a patient who takes lithium daily, a sudden decline in renal function in a patient taking lithium can also lead to acute-on-chronic toxicity
Chronic toxicity: the history generally involves a patient on chronic lithium therapy who, due to toxic drug effects, physical disability, or concurrent illness, becomes hypovolemic, leading to reduced renal excretion of lithium alternatively and toxicity can develop solely from the effects of medications that reduce kidney function

Mild symptoms occur at a level of 1.5-2.5 mEq/L
- Nausea and fatigue
Moderate symptoms occur at a level of 2.5-3.5 mEq/L
- Confusion, increased heart rate, and low muscle tone
Severe symptoms occur at a level > 3.5 mEq/L
- Coma, hypotension, and increased body temperature

Neurological effects	Tremor Hyperreflexia Nystagmus Ataxia Confusion Delirium
Renal effects	Renal toxicity Impaired urinary concentrating ability Nephrogenic diabetes insipidus Sodium-losing nephritis Nephrotic syndrome
Cardiovascular effects	T wave flattening Sinus node dysfunction QT prolongation Intraventricular conduction defects U waves
Gastrointestinal effects	Nausea Vomiting Diarrhea Abdominal pain
Endocrine effects	Hypothyroidism

Lithium prolongs both depolarizing and non-depolarizing neuromuscular block
Perform neuromuscular monitoring in patients on lithium undergoing general anesthesia with the use of neuromuscular blocking agents
Consider conduction defects and ST changes on ECG in patients on lithium undergoing GA