[Symptoms of lithium toxicity at therapeutic levels]

A 60-year-old woman was admitted to the medical psychiatric unit with neurological and psychiatric symptoms. She was being treated with a maintenance dose of lithium for bipolar I disorder. Lithium toxicity and manic state were both considered. However, serum lithium levels appeared to be non-toxic. During hospital admission, her symptoms worsened and many diagnostic tests were performed. Lithium toxicity was considered again and lithium was discontinued, despite therapeutic blood levels. The neuro-psychiatric symptoms subsequently disappeared and the patient improved without residual symptoms. When neuro-psychiatric symptoms occur without elevated lithium levels, the possibility of chronic lithium toxicity should still be considered. More caution is required when risk factors are present, such as: old age, interacting medication, reduced renal function, dehydration and fever. Finally, electroencephalography can contribute to the diagnosis of chronic lithium toxicity.