A 4-year-old boy is brought to the physician for a well-child examination. He is active and healthy with no past medical history. Physical examination shows no abnormalities. His diet consists of vegetables, fish, and chicken, but no read meat. Laboratory studies show:
Hb 10.1 g/dL
MCV 66 μm3
WBC 7,000/μL
Platelets 250,000/μL
Red cell distribution width 11% (NR 13-15%)
Hemoglobin electrophoresis No abnormalities
Direct antiglobulin test Negative
Which of the following is the most likely diagnosis?
