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Published on: Sep 03, 2006
Last modification: Sep 03, 2006
Hereditary spherocytosis
by SirGan|
Hereditary spherocytosis is one specific familial hemolytic disorder characterized by marked heterogeneity of clinical features, ranging from an asymptomatic condition to fulminant and extremely serious hemolytic anemia. The most common characteristic of hereditary spherocytosis is one structure called the microspherocyte- the sphere-shaped red blood cell, which is caused by loss of membrane surface area, and an abnormal osmotic fragility in vitro. Because the spherocytes have a smaller surface area through which oxygen and carbon dioxide can be exchanged- they perform adequately to maintain healthy oxygen supplies. However, they have a high osmotic fragility -when placed into water, they are likely to burst. Problem is that there are many possible complications of this condition and the
Frequency of the conditionAlthough not too many people knew this- the fact is that hereditary spherocytosis is the most common of the hereditary hemolytic anemias among people. Researches done in the past have proven that, in the United States, the incidence of the disorder is approximately 1 case in 5000 people. It is proven that this condition is usually transmitted as an autosomal dominant trait, and the identification of the disorder in multiple generations of affected families is the rule. An autosomal recessive mode of inheritance also occurs. The disease is also encountered worldwide, but its incidence and prevalence in other groups are not established clearly. Anemia or hyperbilirubinemia may be of such magnitude as to require exchange transfusion in the neonatal period. Anemia usually is mild to moderate; however, sometimes it is very severe and sometimes it is not present. Splenomegaly is the rule, and palpable spleens have been detected in more than 75% of affected subjects. Severe hemolytic anemia requires red cell transfusions.
Mechanism of the conditionThe most important thing there is to know about this condition is that the defects in hereditary spherocytosis are in the red cellmembrane. This is because the proteins essential for the integrityof the membrane structure lie immediately under the lipid layer.
 Symptoms of the conditionEvery patient should know that the spleen's hemolysis results directly in varying degrees of anemia and hyperbilirubinemia. These two conditions can result in symptoms of:
Chronic symptoms include:
· anemia
· splenomegaly- enlargement of the spleen
There is also a big problem because the detritus of the broken blood cells called –the bilirubin-accumulates in the gallbladder, and can cause gallstones to develop.
Differential diagnosis of the conditionIt is important to know that this condition can often be misdiagnosed with several other conditions and the most common once are:
Diagnosis of the conditionThere are several possible methods and diagnostic tests in order to get to the proper diagnosis. Some of the most commonly used are:
Lab StudiesPatient should know that the classic laboratory features of this type of anemia include minimal or no anemia, reticulocytosis, an increased mean corpuscular hemoglobin concentration (MCHC), spherocytes on the peripheral blood smear, hyperbilirubinemia, and abnormal results on the osmotic fragility test. Other biochemical changes of hemolysis also are also present, including:
Other laboratory tests used to diagnose this type of anemia include the autohemolysis test and the glycerol-lysis test. The initial workup if hemolysis is suggested should include the following:
Imaging StudiesIf the patient presents with signs and symptoms of hemolysis in addition to right upper abdominal quadrant pain, fever, and leukocytosis, an ultrasound of the biliary tree should be performed to help exclude cholecystitis or cholelithiasis.ProceduresEvery patient should know that, if an aplastic crisis is suggested, further evaluation and platelets should be done in all the cases. This may require a bone marrow biopsy and aspirate to rule out aplasia or megaloblastosis. It is important to point out that obtaining bone marrow aspirate for testing rarely is necessary except in cases of aplastic or megaloblastic crisis.
Histological FindingsAnemia, reticulocytosis, and spherocytosis on peripheral blood smear examination provide strong proofs in order to set the accurate diagnosis of this type of anemia. It is important to know that autoimmune hemolytic anemia also may produce spherocytosis, which usually can be excluded by negative findings on a direct anti-globulin test.
Medical Care – SplenectomyEvery patient should know that the treatment of this type of anemia involves pre-splenectomy care, splenectomy, and post-splenectomy complications. Problem is that children with severe hyperbilirubinemia caused by this type of anemia are at risk for kernicterus, and these infants should be treated with phototherapy and exchange transfusion as clinically indicated.
Splenectomy indications
Indications for splenectomy are not always clear and there are several natures of the doubts!
Splenectomy usually is curative!Good thing about this operation is that red cell survival is improved significantly but it is important to point out that it is not absolutely normal. Post-splenectomy blood changes include an increased hemoglobin level, decreased reticulocyte count, and the appearance of specific inclusion bodies and target cells.
Every patient should know about the possibility of developing fatal sepsis caused by capsulated organisms. This complication is a recognized complication in children who have had a splenectomy.
A simultaneous cholecystectomy in patients with bilirubin stones may eliminate future complications.
Bilirubin gallstonesIt isn't a secret that bilirubin gallstones are found in approximately 50% of patients with hereditary spherocytosis! They are frequently present in patients with very mild disease. It is proven that performing a prophylactic laparoscopic cholecystectomy seems reasonable in this case and it should be pointed out that this procedure helps prevent significant biliary tract disease and, in some patients with mild HS, helps avoid the need for splenectomy. Every parent should be aware of one fact- splenectomy for children with hereditary spherocytosis should be performed when the child is older than 6 years.
Oral folate supplementsWell, it is well known fact that it is traditional for children with chronic haemolysis to receiveoral folate supplements. It would be good if it was like that because- researches are showing that most children in developed countriesconsume well above the minimum daily requirement. Beside that fact, even when children would taking all these supplements- there is nostrong evidence to support universal folate supplementationin hereditary spherocytosis, and it is likely that it is only required in childrenwith severe and moderate HS, but for all patients during pregnancy.
Iron supplementationResearches are showing that iron supplementation supports the increased production of red blood cells, but 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.
ConclusionHereditary spherocytosis is the commonest form of haemolytic anaemia seen in northern Europe ant it is important to know that most children which have mild disease, can live a normal life,and do not require splenectomy. Splenectomyis reserved for those with severe disease or who develop symptomaticgallstones, when cholecystectomy should be performed at thesame time.
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