Which statement about Lithium levels is correct?

Which statement about Lithium levels is correct?

• A. There is no need to monitor levels
• B. Toxic level occurs at 0.5
• C. Therapeutic levels are 0.6 - 1.2 mEq/L, with toxicity risk when >2.0
• D. Therapeutic levels are 2.0 - 3.0

Answer: (C)

Lithium has a very narrow therapeutic window, so regular blood level checks are essential to stay safe and effective. The accepted therapeutic range is 0.6 to 1.2 mEq/L. When levels climb toward about 2.0 mEq/L or higher, the risk of toxicity rises significantly, which is why monitoring is emphasized in practice. This makes the statement that therapeutic levels are 0.6–1.2 with toxicity risk above 2.0 the best fit. Subtherapeutic levels, like 0.5, may not control symptoms, and saying therapeutic levels are 2.0–3.0 would imply toxicity rather than effectiveness.

Lithium has a very narrow therapeutic window, so regular blood level checks are essential to stay safe and effective. The accepted therapeutic range is 0.6 to 1.2 mEq/L. When levels climb toward about 2.0 mEq/L or higher, the risk of toxicity rises significantly, which is why monitoring is emphasized in practice. This makes the statement that therapeutic levels are 0.6–1.2 with toxicity risk above 2.0 the best fit. Subtherapeutic levels, like 0.5, may not control symptoms, and saying therapeutic levels are 2.0–3.0 would imply toxicity rather than effectiveness.