Hemolytic anemia overview: Difference between revisions
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==Risk Factors== | ==Risk Factors== | ||
Risks factors for hemolytic anemia involve insults to [[red blood cells]] or [[Defect|defects]] within [[red blood cells]]. Broadly, the risks factors can be categorized as[[oxidative stress]], mechanical [[injury]], and [[Genetic disorder|genetic conditions]]. | |||
==Screening== | ==Screening== | ||
There is no major role for screening for hemolytic anemia. In some cases, testing for [[Glucose-6-phosphate dehydrogenase deficiency|G6PD deficiency]] can be done if a patient will be receiving medications that are known to precipitate [[oxidative stress]]. | |||
==Natural History, Complications, and Prognosis== | ==Natural History, Complications, and Prognosis== | ||
Revision as of 18:52, 30 October 2017
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Shyam Patel [2]
Overview
Historical Perspective
The history of hemolytic anemia dates back to the 16th century, when the initial experiments were conducted on transfusion of blood. Soon after, the development of the simple microscope revolutionized the study of red blood cells, as red blood cells could be directly observed. After multiple patients began to present with jaundice and splenomegaly, it was observed that there was an association between these symptoms and the destruction of red blood cells. Eventually, it was determined that hemolytic anemia was largely due to immune-mediated mechanisms leading to destruction of red blood cells. Since the 1980s, various immunosuppressive medications have been developed to help treat hemolytic anemia.
Classification
Hemolytic anemia can be divided into intravascular and extravascular based on whether the destruction of RBCs occurs in the vessels or outside the vessels, usually in spleen and liver. Extravascular hemolytic anemia is more common than intravascular hemolytic anemia. There are many types ofhemolytic anemias and the general classification of hemolytic anemia is either acquired or inherited (genetic). Genetic conditions include red blood cellmembrane or enzyme defects that predispose the red blood cells to hemolysis.
Pathophysiology
The pathophysiology of most hemolytic anemia involves complement-activated autoantibodies or non-complement-activated autoantibodies, which result indestruction of red blood cells. The underlying mechanisms is based on immune dysregulation between self and non-self. Numerous drugs including novel anti-cancer therapeutics, can result in immune-mediated hemolysis. On the other hand, the pathophysiology of non-immune-mediated hemolysis relates to structural factors, such as red blood cell membrane and enzyme defects which confer fragility towards red blood cells. In the setting of defects ofred blood cell membranes or anti-oxidant enzymes, there is increased risk for red blood cell destruction.
Causes
The causes for hemolytic anemia can be divided into intracorpuscular or extracorpuscular causes. The intrinsic causes are commonly due to hereditarycauses whereas the extrinsic causes are commonly acquired. Drugs are another major cause of hemolysis. In the era of immunotherapy for cancer, drug-related causes are becoming increasingly important to recognize.
Differentiating Hemolytic Anemia from Other Diseases
The differential diagnosis for hemolytic anemia is broad and includes a variety of conditions that affect red blood cells. Nutritional deficiencies andthalassemias are important components of the differentiation. Certain laboratory tests and physical exam features can help to distinguish these conditions. The treatment of these conditions are quite different, so it is important to distinguish hemolytic anemia from other causes of anemia or other conditions that present similarly.
Epidemiology and Demographics
In general, hemolytic anemia is a relatively rare condition. The incidence and prevalence are fairly low.
Risk Factors
Risks factors for hemolytic anemia involve insults to red blood cells or defects within red blood cells. Broadly, the risks factors can be categorized asoxidative stress, mechanical injury, and genetic conditions.
Screening
There is no major role for screening for hemolytic anemia. In some cases, testing for G6PD deficiency can be done if a patient will be receiving medications that are known to precipitate oxidative stress.