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Jun 20, 2006
AIHA - Autoimmune Haemolytic Anaemia
by SirGan
 Autoimmune hemolytic anemia is a specific disorder that belongs to the group of disorders characterized by a malfunction of the immune system that produces autoantibodies, which attack red blood cells as some substances foreign to the body. This can be the direct result of a drug, toxin, blood parasite, virus or other primary cause or it can be an unexplained immune mediated reaction.When does it occur? Well, the problem is that this autoimmune hemolytic anemia is very uncommon disorder that can occur at any age. These disorders affect women more often than men. In approximately 50% of the cases- the cause of autoimmune hemolytic anemia cannot be determined. This condition is called idiopathic autoimmune hemolytic anemia. It can also be caused by other diseases such as systemic lupus erythematosus, certain drugs such as penicillin etc…
Incidence of the conditionSeveral researches done in the past have proven that on the international level- hemolytic anemia represents approximately 5% of all anemias. The overall incidence of death is low. However, older patients and patients with cardiovascular impairment are at an increased risk. Most of the disorders that lead to hemolysis are not specific to any race or gender.
Signs and symptoms of autoimmune hemolytic anemiaBecause there is often some kind of underlying disorder behind this type of anemia- symptoms are due to both anaemia and the underlying disorder. It is also important to know that patients with minimal haemolytic anaemia can be asymptomatic.
Severe anaemia, especially of sudden onset, may cause:
When destruction persists for a few months or longer, the spleen may enlarge, resulting in a sense of abdominal fullness and, occasionally, discomfort.
Possible causes of hemolytic anemia
This condition could be cause by some red cell membrane abnormalities such as hereditary spherocytosis or elliptocytosis.
Warm antibody type: idiopathic, SLE, lymphoma, chronic lymphatic leukemia, Evans' syndrome. Cold antibody type: cold haemagglutinin disease, paroxysmal cold haemoglobinuria, mycoplasma pneumonia, lymphoma, infectious mononucleosis or other viral infections, chronic lymphatic leukemia.
Drug related: drug absorbed onto red cell surface, e.g. penicillin, cephalosporins, or immune complex mediated, e.g. sulphonamides, quinidine.
Excessive blood loss may also occur over a long period of time (chronic bleeding):
Mechanism and course of the diseaseThe proven fact is that this hemolytic anemia occurs when the bone marrow is unable to compensate premature destruction of red blood cells by increasing their production. Destruction of red blood cells is causing one condition called anemia. They are being destroyed by autoantibodies. This may occur suddenly, or it may develop gradually. What's interesting- in some people, the destruction may stop after a period of time; while in other people, it persists and becomes chronic. What triggers these antibodies to attack these red blood cells- is still unknown! Hemolysis- destruction of the erythrocytes is the final event, what ever is the trigger.
Haemolysis may occur by two mechanisms:
This type occurs most commonly due to complement fixation, trauma, or other extrinsic factors. Most common triggers are:
When we are talking about extravascular type, then we should know that the red cells are removed from the circulation by the mononuclear-phagocytic system either because they are defective. The presence of bound immunoglobulins to their surfaces could also be the cause.
The etiology of premature erythrocyte destruction is diverse and can be due to conditions such as:
Types of hemolytic anemiaThere are two main types of autoimmune hemolytic anemia:
Diagnosis of hemolytic anemiaGood thing about this is that anaemia could be easily identified and defined by simple blood tests measuring the number of red blood cells and the amount of hemoglobin in the blood.
Blood tests
Results of the blood studies should show the next:
Imaging studiesThe ultrasound may be used to estimate spleen size. The physical examination occasionally does not detect significant splenomegaly. Chest radiograph is used to evaluate cardiopulmonary status.
To diagnose an autoimmune type of anemia there is one specific procedure! Autoimmune haemolytic anaemia is diagnosed by the presence of antibodies in the blood that bind to red cells.
Treatment of autoimmune hemolytic anemiaGood thing is that, if symptoms are mild or if destruction of red blood cells seems to be slowing on its own, no treatment will be needed.
The thing is that, if red blood cell destruction is worsening, some corticosteroid drugs such as Prednisone are usually the first choice for treatment. They should suppress the immune system which is usually overactive. Several researches done in the past have showed that high doses should be used at first and then followed by a gradual decreasing of the dose over many weeks or months.
Although not too many people have heard about it, when people do not respond to corticosteroids surgery to remove the spleen is often the next treatment. The operation is called splenectomy. Splenectomy is not recommended in hemolytic disorders such as cold agglutinin hemolytic anaemia.
The fact is that when destruction of red blood cells persists after removal of the spleen or when surgery cannot be performed, immunosuppressive drugs, such as Cyclophosphamide or Azathioprine, are used to suppress the immune system response.
Not too many people have heard about this treatment option. Plasmapheresis is one specific procedure which involves filtering blood to remove antibodies. It is occasionally very helpful when other treatments fail.
The fact is that when red blood cell destruction is severe, blood transfusions are needed. Problem is that they do not treat the cause of the anemia and provide only temporary relief. In these disorders, type matching and cross-matching may be very difficult. The risk of acute hemolysis of transfused blood is high, but the degree is dependent on the rate of infusion.
Studies have shown that this is indicated for patients with severe intravascular hemolysis in which persistent haemoglobinuria has caused substantial iron loss. Because iron stores increase in hemolysis, iron administration generally is contraindicated in hemolytic disorders.
Possible complications
Tips for people with this disorder
Fava beans can cause severe hemolysis in certain populations with this disorder! These patients should avoid eating dishes with fava beans.
Medications and chemicals that should be avoided are:
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