A nurse is caring for a client who has a new prescription for lithium. Which of the following should the nurse monitor during treatment?

• A. Oxygen saturation
• B. Triglyceride
• C. Blood glucose
• D. Sodium

Answer: (D)

Lithium therapy is closely tied to sodium balance because the kidneys handle lithium in the same way they handle sodium. When sodium levels are low or fluid is depleted, the kidneys reabsorb more lithium, which raises lithium blood levels and increases the risk of toxicity. If sodium is normal or high, lithium is more likely to be excreted, but dehydration or other factors can still lead to toxicity, so keeping an appropriate sodium and fluid balance is crucial. Because of this, monitoring sodium helps keep lithium within its safe therapeutic window. In practice, the nurse should assess and maintain normal sodium levels through monitoring hydration status, encouraging consistent salt and fluid intake, and watching for signs of toxicity such as tremor, confusion, ataxia, or gastrointestinal symptoms. Regular labs for lithium levels, kidney function, and thyroid function are also important parts of care. Other measures like oxygen saturation, triglycerides, or blood glucose aren’t targeted to lithium’s primary safety concerns.