Hereditary spherocytosis (HS) is an inherited condition that is the result of molecular abnormalities of proteins of the red cell membrane skeleton. These abnormal red cells are irregular in shape and are subject to splenic sequestration. Patients with this condition may be entirely asymptomatic or may suffer varying forms of hemolytic anemia and splenomegaly. Hemolysis associated with this condition may also be variable. In fact, some patients whose baseline hemoglobin is normal may experience severe hemolysis associated with certain infections such as mononucleosis or parvovirus. Other patients have a chronic severe hemolytic anemia that necessitates transfusions and possible splenectomy.

As stated, the main symptoms are a variable anemia secondary to extravascular hemolysis and splenomegaly. Other potential complications include cholelithiasis and less frequently leg ulcerations. Examination of the peripheral smear reveals multiple spherocytic red cells. Associated laboratory abnormalities include a normocytic anemia, an increased MCHC noted on CBC, an increased osmotic fragility test, elevated levels of LDH, and varying degrees of unconjugated hyperbilirubinemia. The increase in MCHC occurs in approximately half of the patients afflicted with HS and should prompt further workup by determining the osmotic fragility. Other conditions associated with an increased osmotic fragility include homozygous hemoglobin C disease and sickle cell disease. Also, bilirubin gallstones in a young patient or aplastic crisis during either parvovirus or mononucleosis infections should raise the possibility of HS. The differential includes other forms of spherocytic hemolytic anemias such as autoimmune hemolytic anemia, unstable hemoglobins, Rh deficiency syndrome, and hereditary stomatocytosis.

Treatment consists of folic acid supplementation and transfusion therapy when needed. Severe cases may require splenectomy.