Review Question - QID 108614

A 1-year-old male presents to the emergency department with fatigue. His parents also say that they have noticed he is more lethargic and appears weaker compared to usual. The parents report that the patient was born in Malawi and that the family immigrated to the United States shortly after his birth. They endorse 2 similar episodes since he was born that were quite painful for the patient and required analgesics. They deny any recent travel, and the patient has no known exposures. His temperature is 99.0°F (37.2°C), blood pressure is 98/72 mmHg, pulse is 114/min, and respirations are 32/min. On physical exam, the patient appears fatigued and is in pain. Laboratory tests are performed and reveal the following:

Leukocyte count: 11,300/mm^3
Hemoglobin: 8.2 g/dL
Hematocrit: 23%
Mean corpuscular volume: 86 µm^3
Platelets: 492,000/mm^3
Reticulocyte index: 4.0%

A peripheral smear is performed and can be seen in Figure A. The patient is started on folate, hydroxyurea, and is given vaccinations. Which of the following is the most appropriate next step in management?