Lithium Toxicity

• Lithium toxicity is common and occurs in 75 to 90% of patients receiving long-term lithium therapy at some point during their management.  It most often results from inadequate renal excretion.
• Toxic patients typically present with mild side effects such as hand tremor, but other symptoms like weakness, delirium, rigidity, hyperreflexia, altered gait, seizure, and EEG changes may also result.
• While severe lithium toxicity typically correlates with elevated serum levels, not all patients with high lithium levels present with advanced symptoms, at least in the early stages; this is due to delayed distribution within tissues.  Similarly, patients with lower serum levels of lithium may present with advanced symptoms, if the drug has accumulated in the cerebrospinal fluid to a greater extent than it has the serum. 

References

• Groleau G.  Lithium toxicity. Emerg Med Clin North Am 1994; 12:511-31.
• Kondziela J.  Extreme lithium intoxication with severe symptoms. Hosp Comm Psychiatry 1984; 35:727-8.