Diagnostic approach to isolated anemia in children: Morphologic classification

HGB: hemoglobin; MCV: mean corpuscular volume; TIBC: total iron-binding capacity; TEC: transient erythroblastopenia of childhood; G6PD: glucose-6-phosphate dehydrogenase; HUS: hemolytic uremic syndrome; TTP: thrombotic thrombocytopenic purpura; DIC: disseminated intravascular coagulation; HU: hydroxyurea; PMNs: polymorphonuclear cells; LDH: lactate dehydrogenase; DAT: direct antiglobulin test; RDW: red cell distribution width.

* HGB levels in children vary considerably by age. During adolescence, HGB values also differ according to sex. When diagnosing anemia in pediatric patients, HGB values should be compared with age- and sex-adjusted norms. Mild anemia occurring at 6 to 9 weeks of life is consistent with "physiologic anemia" and is not pathologic. Falsely elevated HGB values may occur when measured using capillary samples (eg, finger or heel "sticks"), particularly when using microhematocrit measurements. Spurious results may also occur with automated counters in the presence of lipemia, hemolysis, leukocytosis, or high immunoglobulin levels.

¶ The RDW can be helpful in differentiating thalassemia from iron deficiency. High RDW is typical of iron deficiency, whereas the RDW is usually normal in patients with thalassemia (though elevated RDW can occur).

Δ Anemia of chronic disease typically presents as a normocytic anemia but can have low MCV.

◊ Selected testing is based upon review of the patient's history and examination of the peripheral blood smear.

§ In children with mild microcytic anemia and dietary history that is suggestive of iron deficiency, serum iron studies (ie, ferritin, iron, and TIBC levels) are generally not necessary. In these children, a therapeutic trial of iron can be used to confirm the diagnosis.

¥ Evidence of hemolysis includes jaundice, indirect hyperbilirubinemia, elevated lactate dehydrogenase, and/or decreased haptoglobin.