A 29-year-old female presents with fatigue and shortness of breath on exertion. She has no family history of anemia. She has experienced heavy menstrual cycles for the past six months. On physical examination, she is normal except for pallor. Laboratory findings show a hemoglobin level of 9 (12–16), a platelet count of 480,000 (150,000– 400,000), an RDW of 15 (11.5–14.5), and an MCV of 65 (80–100). What is the next step in the evaluation of this patient?