A nurse is caring for a client who has a prescription for levothyroxine.Which of the following laboratory tests should the nurse monitor?

Choice B rationale:Prothrombin time. Monitoring prothrombin time is not typically required for clients taking levothyroxine. Prothrombin time is a measure of blood clotting and is not directly affected by thyroid hormone replacement therapy.Choice C rationale:Blood urea nitrogen. Monitoring blood urea nitrogen is not specifically related to levothyroxine therapy. Blood urea nitrogen is a measure of kidney function and is not typically affected by thyroid hormone replacement.Choice D rationale:Serum potassium. Monitoring serum potassium levels is important for some medications, but it is not a primary concern when a client is taking levothyroxine. Levothyroxine is primarily used to replace or supplement thyroid hormones, and its main focus is on thyroid function.Choice A rationale:Triiodothyronine. Triiodothyronine (T3) is one of the thyroid hormones, and monitoring its levels is essential when a client is taking levothyroxine. Levothyroxine is a synthetic form of thyroxine (T4), which the body converts into triiodothyronine (T3) Monitoring T3 levels helps ensure that the client's thyroid hormone replacement therapy is effective and that they are not experiencing over- or under-dosage.