Anemia of Prematurity Workup

Updated: Jan 08, 2016
  • Author: George Cassady, MD; Chief Editor: Ted Rosenkrantz, MD  more...
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Approach Considerations

The following are useful laboratory studies:

CBC count - White blood cell (WBC) and platelet values are normal in AOP. Low hemoglobin values, below 10 g/dL, are found. They may descend to a nadir of 6-7 g/dL. Lowest levels are generally observed in the smallest infants. Red blood cell indices are normal (eg, normochromic, normocytic) for age.

Reticulocyte count - The reticulocyte count is low when the degree of anemia is considered, as a result of the low levels of erythropoietin (EPO). Conversely, an elevated reticulocyte count is not consistent with the diagnosis of AOP.

Peripheral blood smear - Red blood cell morphology should be normal. Red blood cell precursors may appear to be more prominent.

Maternal and infant blood typing; direct antibody test (Coombs) - The direct Coombs test result may be coincidentally positive. Despite this, it is important to ensure an immune-mediated hemolytic process related to maternal-fetal blood group incompatibility (hemolytic disease of the newborn) is not present.

Serum bilirubin - An elevated serum bilirubin level should suggest other possible explanations for the anemia. These would include hemolytic entities, such as G-6-PD deficiency or other kinase/isomerase/enzyme deficiencies, or more common causes such as infection or hemolytic disease of the newborn.

Lactic acid - Elevated lactic acid levels have been suggested by some to be useful as an aid to determine the need for transfusion.