Family Medicine Practice Question of the Week

A 6-month-old Caucasian male infant presents for a well child visit and immunizations. The mother reports that he has had no recent illnesses, but he is nursing for shorter periods of time and is taking an extra nap in the middle of the day. His past medical history is notable for hyperbilirubinemia in the newborn period, which required phototherapy. Both he and his mother are blood type O positive. Family history is significant for the patient’s father having a cholecystectomy and splenectomy at 15 years of age. Physical exam is notable for slight pallor of the skin and conjunctiva; there is a faint yellow cast to the skin. The spleen tip is palpable 1 cm below the left costal margin.

Results of a complete blood count are:

• WBC 11,500/mm3, with 31% neutrophils, 60% lymphocytes, 6% monocytes, and 3% eosinophils
• RBC 3.7 million/mm3, hemoglobin 10.0 g/dL, hematocrit 23%, MCV 76 fL, MCHC 36 g/dL, RDW 15%
• Platelets 200,000/mm3