An adult client who is admitted to the mental health unit for treatment of bipolar disorder has a slightly slurred speech pattern and an unsteady gait. Which assessment finding is most important for the nurse to report to the healthcare provider? Reference Range: Blood alcohol level [0 to 0.05% (0 to 10.9 mmol/L] Lithium [0.8 to 1.2 mEq/L (0.8 to 1.2 mmol/L)]

A. Blood alcohol level of 0.09% (19.5 mmol/L): This alcohol level indicates mild intoxication. It can cause slurred speech and gait changes, but the effects are usually transient and less concerning than drug toxicity. It should be monitored, but is not as urgent as lithium toxicity. B. Weight loss of 10 lb (4.5 kg) in past month: This degree of weight loss may suggest poor nutritional intake or a depressive episode, but it is not immediately life-threatening. It requires follow-up but does not explain the acute neurological signs the client is exhibiting. C. Six hours of sleep in the past three days: Severe sleep deprivation can exacerbate mood instability in bipolar disorder, but it does not account for slurred speech or gait disturbances. This concern is significant for mental health management but not the priority in this situation. D. Serum lithium level of 1.6 mEq/L (1.6 mmol/L): This is above the therapeutic range and suggests lithium toxicity, which can cause neurological signs such as slurred speech and ataxia. Immediate reporting is crucial to prevent progression to more severe toxicity, including seizures or coma.