Hemolytic anemia

Hemolytic anemia is a type of anemia caused by abnormal destruction of red blood cells.  As a result of the overly frequent breakdown of red blood cells in these patients, the body also breaks down more hemoglobin than usual.  This causes an increase in bilirubin, increase in excreted urobilinogen, and high hemoglobin in the blood and urine.  To compensate for the loss of red blood cells, the body produces extra cells quickly from the bone marrow, resulting in a high concentration of reticulocytes (immature red blood cells) in the blood.

Hemolytic anemia patients display the general symptoms seen in other anemias, including paleness, shortness of breath and fatigue.  Chronic hemolysis (destruction of red cells) can cause gallstones, which for many patients is their first distinct symptom.  The high amount of free hemoglobin can cause fainting and chest pain due to increased pressure in the pulmonary artery, known as pulmonary hypertension.

Hemolytic anemia can have many causes.  Defective hemoglobin, as seen in sickle-cell disease and thalassemia, is one reason.  Defective red cell membrane, like in hereditary elliptocytosis, is another.  Defective red cell metabolism, such as glucose-6 phosphate dehydrogenase deficiency (G6PD), can cause hemolytic anemia.  All of these forms are inherited.

A variety of outside factors can cause hemolytic anemia.  Mycoplasma pneumoniae infection (“Walking pneumonia”) can cause episodes of hemolysis.  Autoimmune hemolytic anemia, which is more likely in the presence of autoimmune or hematologic abnormalities, can onset at any age.  Hypersplenism, overworking of the spleen, can cause hemolytic anemia.  Frequent runners often have hemolytic anemia due to hemolysis in the feet from the constant impact.

A blood smear observed by microscope is crucial for diagnosis.  Fragmented red cells known as schistocytes will be present.  Reticulocytes are present in higher numbers.  Other lab tests, such as bilirubin and lactate dehydrogenase levels, are needed.  Further testing can determine the nature of the hemolysis (autoimmune, etc.)

In cases of dramatically low blood count, transfusions may be necessary.  For autoimmune hemolytic anemia, long term steroid therapy is sometimes required.  Removal of the spleen may also be considered as part of managing the disease.

Upon receiving transfusions, some patients (including those without a history of hemolysis) exhibit a hemolytic reaction.  It is the opinion of some medical providers that these hemolytic reactions are actually a form of anaphylaxis.  Some patients with hemolytic anemia exhibit more severe hemolysis during anaphylaxis.