A nurse is caring for a client who has been taking epoetin alfa for 3 months. Which of the following laboratory tests should the nurse monitor to determine the effectiveness of the medication?

A. T4 is a thyroid hormone, and monitoring it is not relevant for assessing the effectiveness of epoetin alfa. B. Troponin is a marker for cardiac injury and is not relevant for assessing the effectiveness of epoetin alfa. C. Epoetin alfa stimulates the production of red blood cells, so monitoring hemoglobin levels is crucial to assess its effectiveness. D. AST is a liver enzyme and is not relevant for assessing the effectiveness of epoetin alfa.