Review Question - QID 108675

An 8-year-old male presents to his pediatrician for a follow-up appointment for persistent fatigue. His mother reports that the patient’s teacher called her yesterday to tell her that her son has been sitting out of recess every day for the past week. The patient first developed symptoms of fatigue and weakness several years ago and has returned to the physician with similar episodes a few times per year. These episodes seem to sometimes be triggered by viral illnesses but others have no identifiable trigger. The patient has been on daily folate supplementation with some improvement and requires red blood cell transfusions several times a year. He has an allergy to sulfa drugs and last month he was treated with amoxicillin for an ear infection. His paternal grandfather was recently diagnosed with multiple myeloma, but his parents deny any other family history of hematologic conditions. His temperature is 99.0°F (37.2°C), blood pressure is 103/76 mmHg, pulse is 95/min, and respirations are 14/min. On physical exam, the patient is tired-appearing with conjunctival pallor. Laboratory tests performed during this visit reveal the following:

Leukocyte count: 9,700/mm^3
Hemoglobin: 8.4 g/dL
Hematocrit: 27%
Mean corpuscular volume: 97 µm^3
Mean corpuscular hemoglobin concentration (MCHC): 40% Hb/cell
Platelet count: 338,000/mm^3
Reticulocyte index (RI): 4.2%

Which of the following is the most appropriate next step in management?