Unrecognized delayed toxic lithium peak concentration in an acute poisoning with sustained release lithium product

A 32-year-old female with a history of bipolar disorder was admitted after taking approximately 16 g of an extended-release lithium carbonate formulation in an attempted suicide. Five hours after consumption, the lithium serum level was 3.2 mEq/L. Fourteen hours after consumption, the lithium level was 5.1 mEq/L and the patient was asymptomatic. Due to a level >4 mEq/L, the patient was transferred to a renal medicine service for hemodialysis. The lithium concentration 6 hours after the hemodialysis was 2.54 mEq/L. Thirty seven hours after the consumption (15 hours after hemodialysis), lithium levels increased up to 6.09 mEq/L. A second hemodialysis session was performed, which successfully reduced the serum lithium concentration to 1.86 mEq/L. Lithium levels 85 hours after the consumption were 0.61 mEq/L and the patient was transferred to the Psychiatry Department. Unrecognized delayed toxic peak lithium concentration may appear in an acute poisoning with a sustained release lithium product. Therefore, patients presenting with acute intoxication with extended release formulations should be managed with caution, and continued drug monitoring is suggested.