To the Editor: Lithium is generally contraindicated in patients with impaired renal function because of its nephrotoxic effects. However, once end-stage renal disease develops, lithium carbonate can be used in conjunction with hemodialysis for the treatment of patients with bipolar affective disorder, as first reported by Procci in 1977 (1). We report a case of successful lithium carbonate maintenance therapy in a hemodialysis patient, complicated by lithium toxicity.
"Mr. B" was a 68-year-old man with a 30-year history of bipolar affective disorder. In 2001, he was admitted to the hospital for acute renal failure following an alcoholic binge and rhabdomyolysis, and he subsequently developed end-stage renal disease. Hemodialysis was initiated in 2004, and the patient remained anuric.
Over the next several years, the patient failed treatment with a series of different mood stabilizing agents. He experienced drug-induced fever with carbamazepine, decreased mental acuity with olanzapine, worsening of a preexisting tremor with valproic acid, and little therapeutic effect with oxcarbazepine and lamotrigine. In 2008, he refused further treatment with valproic acid and was started on lithium carbonate (600 mg), administered orally following 3-hour dialysis sessions three times per week.
Over the following 2 years, the patient's serum lithium concentrations were maintained in the range of 0.6—0.8 mmol/l. He reported a subjective improvement in his tremor, and his manic symptoms (hypersexuality, yelling, decreased sleep, religious delusions) were generally under much better control, with only two episodes of hypomania and one episode of overt mania occurring over the course of 2 years, a great improvement over his prior course.
In April 2010, Mr. B started to exhibit signs of hypomania, and his lithium dose was increased to 900 mg, with a subsequent serum level of 0.84 mmol/l. One month later, he exhibited somnolence and slurred speech, and laboratory testing revealed a lithium concentration level of 1.42 mmol/l. His subsequent postdialysis lithium concentration level was 0.31 mmol/l. The lithium dose was reduced to 600 mg, but the following predialysis lithium concentration level was once again elevated, at 1.41 mmol/l. This was believed to be as a result of reequilibration from the intracellular space following clearance of the drug from the extracellular space during dialysis (2). After two more dialysis sessions, the patient's serum lithium level stabilized at 0.75 mmol/l, and he exhibited improved mental status.
In conclusion, lithium carbonate maintenance therapy was successfully used in the patient presented in this case, but the experience of lithium toxicity underscores the delicate nature of lithium balance in hemodialysis patients, with particular attention to reequilibration between the intra- and extracellular spaces, and perhaps an increased vulnerability to toxicity, even at levels <1.5 mmol/l.