From the Guidelines
The key signs of lithium toxicity include nausea, vomiting, diarrhea, tremors, drowsiness, confusion, and muscle weakness, and can be life-threatening if not promptly addressed. To monitor for lithium toxicity:
- Check serum lithium levels regularly, aiming for 0.6-1.2 mEq/L for most patients, as recommended by recent guidelines 1.
- Watch for symptoms, especially in patients with reduced kidney function or those taking medications that interact with lithium, such as NSAIDs 1.
- Be alert for changes in fluid balance, as dehydration can increase lithium levels. Patients should seek immediate medical attention if they experience persistent gastrointestinal symptoms, significant tremors, or confusion while on lithium therapy. Lithium has a narrow therapeutic index, meaning the difference between therapeutic and toxic levels is small, and regular monitoring of serum lithium concentrations is necessary, with levels determined twice per week during the acute phase and until the serum concentrations and clinical condition of the patient have been stabilized 1. Healthcare providers should adjust dosage based on serum levels and clinical presentation, taking into account the potential risks and benefits of lithium therapy, particularly in patients with kidney disease or those taking interacting medications 1. It is essential to weigh the risk-benefit of lithium in specific situations, especially in pregnant or breastfeeding women, and to maintain hydration during intercurrent illness to minimize the risk of toxicity 1.
From the FDA Drug Label
ADVERSE REACTIONS Lithium toxicity: The likelihood of toxicity increases with increasing serum lithium levels. Serum lithium levels greater than 1.5 mEq/l carry a greater risk than lower levels. However, patients sensitive to lithium may exhibit toxic signs at serum levels below 1. 5 mEq/l. Diarrhea, vomiting, drowsiness, muscular weakness and lack of coordination may be early signs of lithium toxicity, and can occur at lithium levels below 2 mEq/l. At higher levels, giddiness, ataxia, blurred vision, tinnitus and a large output of dilute urine may be seen. Information for the patients: Outpatients and their families should be warned that the patient must discontinue lithium therapy and contact his physician if such clinical signs of lithium toxicity as diarrhea, vomiting, tremor, mild ataxia, drowsiness, or muscular weakness occur
The signs of lithium toxicity include:
- Early signs:
- Diarrhea
- Vomiting
- Drowsiness
- Muscular weakness
- Lack of coordination
- Signs at higher levels:
- Giddiness
- Ataxia
- Blurred vision
- Tinnitus
- Large output of dilute urine 2
From the Research
Signs of Lithium Toxicity
The signs of lithium toxicity can vary from mild to severe and can affect multiple organs, with the primary site of toxicity being the central nervous system 3. Some common signs of lithium toxicity include:
- Confusion 4, 3
- Ataxia 4, 5, 3, 6, 7
- Lethargy 4
- Bizarre behavior 4
- Diarrhea 5
- Tremor 5, 6
- Muscle weakness 5
- Myoclonus 5
- Seizures 5, 3
- Coma 5, 3
- Death 5
- Dysrhythmias 5
- Cardiomyopathies 5
- Myocardial infarction 5
- Dysarthria 6, 7
- Encephalopathy 6
Severity of Lithium Toxicity
Severe lithium toxicity can present with life-threatening symptoms such as seizures, coma, and death 5, 3. Chronic lithium poisoning can require a prolonged hospital length of stay due to impaired mobility and cognition, and associated nosocomial complications 3. Persistent neurological deficits, particularly cerebellar, can occur and are poorly understood, but appear to be uncommon in uncomplicated acute poisoning 3.
Treatment of Lithium Toxicity
Lithium is readily dialyzable, and extracorporeal treatments may be used to reduce the risk or duration of toxicity in high-risk exposures 3. Post-acute rehabilitation for ataxia associated with acute lithium toxicity may improve ataxia and the ability to perform activities of daily living 6.