A nurse is caring for a client who has a new prescription for lithium carbonate. Prior to administering the first dose, which of the following laboratory values should the nurse evaluate?

Choice A reason: Arterial blood gases are not routinely required before initiating lithium therapy. They are more relevant in respiratory or metabolic disorders, not in baseline monitoring for lithium. Choice B reason: Total cholesterol is not directly affected by lithium therapy. While metabolic monitoring may be necessary for some psychiatric medications, cholesterol is not a priority baseline test for lithium. Choice C reason: Thyroid hormones should be evaluated because lithium can interfere with thyroid function, leading to hypothyroidism. Baseline thyroid levels are essential to monitor for potential adverse effects during therapy. Choice D reason: Hemoglobin levels are not directly impacted by lithium therapy. While general health screening may include hemoglobin, it is not a priority baseline test specific to lithium administration.