The nurse is providing medication teaching to a client with bipolar disorder who receives a prescription for lithium carbonate. Which instruction should the nurse emphasize with the client?

A. Avoid taking the medication on an empty stomach: While it can be helpful to take lithium with food to minimize gastrointestinal upset, it is not the primary instruction for lithium use. The most important aspect of lithium therapy involves fluid balance and monitoring. B. Keep medication fliers for frequent review and reference: While reviewing medication information is useful, it is not as critical as maintaining appropriate fluid intake and monitoring for side effects specific to lithium. C. Maintain a fluid intake of 1500 to 3000 mL per day: This is crucial because lithium levels can be affected by changes in fluid balance. Inadequate fluid intake can lead to dehydration, which can increase lithium levels and the risk of toxicity. Therefore, maintaining adequate hydration is essential for safe lithium use. D. Report fluctuations in weight to the healthcare provider: While fluctuations in weight can be relevant for overall health monitoring, the more immediate concern with lithium therapy is to maintain proper fluid intake and monitor for signs of toxicity or dehydration.