Spherocytosis
Overview
Spherocytosis is an auto-hemolytic anemia (a disease of the blood) characterized by the production of red blood cells (RBCs), or erythrocytes, that are sphere-shaped, rather than bi-concave disk shaped. It is caused by a molecular defect in one or more of the proteins of the red blood cell cytoskeleton, including, spectrin, ankyrin, Band 3, or Protein 4.2. Because the cell skeleton has a defect, the blood cell contracts to its most surface-tension efficient and least flexible configuration, a sphere. The sphere-shaped red blood cells are known as spherocytes
Symptoms
The spleen's hemolysis results directly in varying degrees of anemia and hyperbilirubinemia, which in turn result in symptoms of fatigue, pallor, and jaundice. Acute cases can threaten hypoxemia through anemia and acute kernicterus through hyperbilirubinemia, particularly in newborns. Chronic symptoms include anemia and splenomegaly, a potentially life-threatening enlargement of the spleen due to its increased activity. Furthermore, the detritus of the broken-down blood cells--bilirubin--accumulates in the gallbladder, and can cause pigmented gallstones or "sludge" to develop. In chronic patients, an infection or other illness can cause an increase in the destruction of red blood cells, resulting in the appearance of acute symptoms, a hemolytic crisis
Diagnosis
In peripheral blood smears, many of the red blood cells will appear abnormally small and will lack the central pallor--the lighter area in the middle of an RBC as seen under a microscope. The CBC (cell blood count) laboratory values will show elevated MCHC. The splenic cords are congested with red blood cells to be destroyed and macrophages of the spleen will show signs of actively destroying erythrocytes (erythrophagocytosis). This will result in an elevated bilirubin level. The bone marrow in its role of manufacturing red blood cells will display hyperplasia, the increased activity of replacing RBCs. As a result, immature red blood cell--or reticulocyte--counts will appear elevated
Treatment
Treatment of acute symptoms Acute symptoms of anemia and hyperbilirubinemia can indicate treatment with blood transfusions or exchanges. Transfusions treat anemia by adding healthy donor blood to the patient's own, providing needed red blood cells. As the transfused blood does not contain spherocytes, it will not be hemolysed per se, but the overactive spleen may still break down a significant proportion of the transfused blood. Exchanges treat hyperbilirubinemia by replacing some portion of the patient's blood with healthy donor blood, thus removing some portion of the toxic bilirubin. [edit]Treatment of chronic symptoms Chronic symptoms of anemia and splenomegaly typically indicate dietary supplementation of folic acid and eventual treatment by splenectomy, the surgical removal of the spleen. In longstanding cases in which patients have taken supplemental iron or received numerous blood transfusions, iron overload may be a significant problem, being a potential cause of cardiomyopathy and liver disease. If there is iron overload, chelation therapy with agents such as desferrioxamine may be necessary. While splenectomy does not affect the shape of the blood cells, it does remove the more obvious physical symptoms of the disorder, as the blood cells are no longer constantly broken down. Though it offers near-immediate relief from symptoms, splenectomy is often not performed until the patient is in late childhood, so as not to hinder the patient's ability to fight off childhood infections. The surgery is often performed laparoscopically. Given that surgery is preplanned, it is highly recommended that patients receive prior Pneumovax-II pneumococcus, conjugated-C meningococcus & Haemophilus influenzae type b vaccinations to combat the patient's new lower tolerance against overwhelming post-splenectomy infection. The Pneumovax needs repeating every six years and the patient should have a yearly influenza vaccine. Prophylactic antibiotics are also given. (See asplenia for further details on these measures). [edit]Treatment of the disorder Both measures described above treat the symptoms, not the cause of the disorder. Non-hereditary spherocytosis has several causes, each treated differently. Experimental gene therapy exists to treat hereditary spherocytosis in lab mice; however, this treatment has not yet been tried on humans and because of the risks involved in human gene therapy, it may never be. See also Hereditary spherocytosi