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. Serum lithium levels above 3 mEq/l may produce a complex clinical picture involving multiple organs and organ systems
The signs and symptoms 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
- Severe toxicity (levels above 3 mEq/l): a complex clinical picture involving multiple organs and organ systems 1
From the Research
Introduction to Lithium Toxicity
Lithium toxicity is a potentially life-threatening condition that can occur in patients taking lithium for therapeutic purposes, such as bipolar affective disorder [(2,3,4)]. The clinical diagnosis of lithium intoxication can be elusive due to the slow onset and diversity of toxic manifestations 2.
Signs and Symptoms of Lithium Toxicity
The signs and symptoms of lithium toxicity can vary from asymptomatic supratherapeutic drug concentrations to clinical toxicity, including:
- Mental status changes [(2,3)]
- Neurologic symptoms, such as confusion, ataxia, or seizures [(3,4)]
- Gastrointestinal symptoms 5
- Cardiovascular symptoms 6
- Renal symptoms 6
Diagnosis of Lithium Toxicity
The diagnosis of lithium intoxication is largely clinical, although the EEG may help if typical, non-specific EEG changes are present 3. The red cell:plasma lithium ratio may be a sensitive indicator of intoxication, if available 3. Serum lithium levels may be unreliable when evaluating patients for toxicity, as levels may not be elevated in patients on chronic lithium therapy 5.
Treatment of Lithium Toxicity
Treatment of lithium toxicity depends on the clinical presentation and serum lithium level 2. Hemodialysis is the treatment of choice for severe lithium intoxication [(2,4,6)]. The decision to initiate hemodialysis should be based on the patient's clinical condition, rather than solely on the serum lithium level 6.
Dosing and Monitoring
Careful attention to dosing, monitoring, and titration is required to prevent lithium toxicity 4. Patients with impaired kidney function, such as those with lithium-induced nephrogenic diabetes insipidus, are at increased risk of toxicity 4.
Caveats and Differentials
It is essential to consider the possibility of artificial lithium toxicity, which can occur if blood is collected in a tube containing lithium heparin 5. Additionally, patients with chronic lithium poisoning may require a prolonged hospital length of stay due to impaired mobility and cognition, and associated nosocomial complications 4. Persistent neurological deficits, particularly cerebellar, can occur in patients with lithium toxicity, although the incidence and risk factors for its development are poorly understood 4.