What is the therapeutic lithium range for bipolar disorder?

• A. 0.4-0.8
• B. 0.6-1.2
• C. 1.5-2.0
• D. 2.0-3.0

Answer: (B)

Lithium works with a very narrow therapeutic index, so the goal is to keep its level just high enough to control mood symptoms but low enough to avoid toxicity. For adults with bipolar disorder, the target therapeutic range is about 0.6 to 1.2 mEq/L. Levels below this may be subtherapeutic and ineffective at stabilizing mood, while levels around 1.5 mEq/L or higher increase the risk of toxicity, presenting with tremors, GI upset, confusion, ataxia, and more severe neurologic or renal problems if levels rise further. Because of this, clinicians monitor blood lithium levels after starting therapy and adjust dosing gradually, also emphasizing adequate hydration and consistent salt intake since changes in sodium can raise or lower lithium levels. The other ranges are either too low to be effective or indicate toxicity, which is why 0.6–1.2 mEq/L is the best choice.