Lithium becomes toxic at serum levels above:

Lithium becomes toxic at serum levels above:

• A. 1.0
• B. 1.2
• C. 1.5
• D. 2.0

Answer: (C)

Lithium has a narrow therapeutic window, so it’s crucial to keep levels within a safe range. The therapeutic range is about 0.6–1.2 mEq/L. Toxicity tends to begin when the serum level exceeds roughly 1.5 mEq/L. Therefore, among the numbers given, 1.5 mEq/L marks the onset of toxicity. Levels at 1.0 and 1.2 are still within therapeutic limits, while 2.0 mEq/L indicates more pronounced toxicity.

Lithium has a narrow therapeutic window, so it’s crucial to keep levels within a safe range. The therapeutic range is about 0.6–1.2 mEq/L. Toxicity tends to begin when the serum level exceeds roughly 1.5 mEq/L. Therefore, among the numbers given, 1.5 mEq/L marks the onset of toxicity. Levels at 1.0 and 1.2 are still within therapeutic limits, while 2.0 mEq/L indicates more pronounced toxicity.