Lithium

Lithium, a mood stabilizer used in bipolar disorder, has a narrow therapeutic index (small difference between therapeutic and toxic levels}. This patient's gradual onset of neurologic symptoms (slurred speech, confusion, tremors, and ataxia) is consistent with chronic lithium toxicity. Therapeutic lithium levels are 0.8- 1.2 mEq/L. Serum lithium levels >1.5 mEq/L confirm toxicity, and levels ;::2 .5 mEq/L require emergency management.