In the newborn period accelerated RBC destruction associated with congenital hemolytic anemia may result in marked elevation of bilirubin levels. The rate at which serum indirect bilirubin increases may be similar to that observed for iso- immune hemolytic anemias. Hemoglobin defects that involve the alpha chain may present neonatally, but usually do not cause hemolysis unless cells are exposed to additional stress. Beta- globin chain defects such as sickle cell disease or thalassemia are not clinically evident until the switch from fetal to adult hemoglobin synthesis. The peripheral smear should be looked at closely.
Target cells are prominent in patients with hemoglobinopathies and obstructive liver disease.
5- nucleotidase deficiency. There may also be evidence of microangiopathic hemolysis. The reticulocyte count, if elevated in the presence of a falling or stable hemoglobin level, is usually the only test necessary to direct the diagnostic work- up toward causes of hemolytic anemia. An indirect bilirubin and serum haptoglobin measurement may be useful. Haptoglobin, the serum transport protein for hemoglobin, becomes low in the presence of both extravascular and intravascular hemolysis.