Prior to administering the first dose of lithium carbonate, which lab value should the nurse evaluate?

Evaluating the sodium level prior to administering the first dose of lithium carbonate is crucial because lithium has a narrow therapeutic window and its levels are significantly affected by sodium levels in the body. Lithium and sodium compete for reabsorption in the kidneys, meaning that low sodium levels can lead to increased lithium retention, raising the risk of toxicity. Conversely, if sodium levels are elevated, it can lead to decreased lithium levels, potentially leading to inadequate therapeutic effects.

Monitoring sodium values helps ensure that the patient is at a stable baseline before starting lithium treatment. This is particularly important because fluctuations in sodium due to dehydration, excessive sweating, or certain medications can significantly impact lithium levels. Therefore, assessing sodium levels before commencing therapy is a fundamental nursing responsibility to ensure patient safety and effective treatment outcomes.