MCHC, or mean corpuscular hemoglobin concentration, is used to measure the concentration of hemoglobin in a given volume of packed RBCs. It is elevated in hereditary spherocytosis, as the cell is dehydrated and the membrane surface area is decreased.
As spectrin and ankyrin, which interact with the RBC membrane, are commonly defective, the RBC membrane is no longer anchored. Small, round, spherical RBCs are formed, which have no central pallor.
RBCs need to be flexible to pass through the spleen (cords of Billroth). As spherocytes are less flexible and abnormally shaped, they bottleneck in the spleen. They are then phagocytosed, leading to hemolysis. Thus, this disease is characterized as a normocytic (normal sized) anemia, which is intrinsic and extravascular.
This is the gold standard for diagnosing hereditary spherocytosis, though it has a high false negative rate. In this test, spherocytes easily rupture in hypotonic solutions due to increased membrane permeability to salt and water.
Splenectomy, or surgical removal of the spleen, is indicated for moderate to severe cases of hereditary spherocytosis. Patients post-splenectomy are more susceptible to encapsulated bacterial infections, and on lab examination may show Howell-Jolly bodies.
As hereditary spherocytosis is an anemia, folic acid is supplemented to patients. Folic acid helps develop healthy RBCs. Furthermore, patients are creating more RBCs continuously, due to increased demand (as spherocytes are being destroyed). Thus, a folate deficiency may occur due to increased bone marrow demand.
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