A client prescribed lithium carbonate 300 mg twice daily three months ago comes to the emergency department with mental confusion, ataxia, excessive diluted urine (polyuria), and blurred vision. Which lithium level would the nurse expect?

Choice A reason: A lithium level of 1.2 mEq/L is within the therapeutic range (0.6–1.5 mEq/L) for bipolar disorder. Symptoms like confusion, ataxia, polyuria, and blurred vision indicate toxicity, which occurs at higher levels, typically above 1.5 mEq/L, making this level unlikely for these severe symptoms. Choice B reason: A lithium level of 1.4 mEq/L is at the upper end of the therapeutic range. While mild side effects may occur, severe symptoms like mental confusion, ataxia, and polyuria suggest toxicity, which typically occurs at levels above 1.5 mEq/L, ruling out this option. Choice C reason: A lithium level of 2.3 mEq/L indicates toxicity, causing neurological symptoms (confusion, ataxia), polyuria due to nephrogenic diabetes insipidus, and blurred vision from central nervous system effects. These symptoms align with lithium toxicity, which occurs at levels above 1.5 mEq/L, making this the expected level. Choice D reason: A lithium level of 1.8 mEq/L is slightly above therapeutic range and may cause mild toxicity symptoms, such as tremor or nausea. However, the severe symptoms described (confusion, ataxia, polyuria) are more consistent with higher toxic levels, such as 2.3 mEq/L, making this less likely.