The approach to anemia in the pediatric patient is reviewed here. Included are pertinent issues related to the history and physical examination, the initial laboratory workup, methods for classifying anemia, and algorithms designed to help guide diagnosis.
A systematic approach to the examination of the peripheral blood smear and bone marrow is discussed separately. (See "Evaluation of the peripheral blood smear" and "Evaluation of bone marrow aspirate smears".)
DEFINITION OF ANEMIA
Anemia may be defined as a reduction in red blood cell (RBC) mass or blood hemoglobin concentration. In practice, anemia most commonly is defined by reductions in one or both of the following:
- Hematocrit (HCT) — The hematocrit is the fractional volume of a whole blood sample occupied by red blood cells (RBCs), expressed as a percentage. As an example, the normal HCT in a child age 6 to 12 years is approximately 40 percent.
- Hemoglobin (HGB) — This is a measure of the concentration of the RBC pigment hemoglobin in whole blood, expressed as grams per 100 mL (dL) of whole blood. The normal value for HGB in a child age 6 to 12 years is approximately 13.5 g/dL.
The threshold for defining anemia is a HGB or HCT that is more than two standard deviations below the mean for the reference population. Normal ranges for HGB and HCT vary substantially with age; thus, it is particularly important to use age and sex adjusted norms when evaluating a pediatric patient for anemia (table 1). In addition, there is racial variation, with healthy black children having average hemoglobin values 0.5 g/dL below that of white children of the same age and sex .