Autoimmune Hemolytic Anemia: An Autoimmune Disorder that can Damage Your Heart

Hemolytic anemia is a condition in which red blood cells break down faster than the body can build them. In healthy individuals, red blood cells usually live between 90 and 120 days, which means that around one percent of the red blood cells die each day.

What is autoimmune hemolytic anemia?

The bone marrow builds about the same number of red blood cells each day. If red blood cells die faster than normally for any reason, the body can compensate for this loss by accelerating the production of red blood cells up to a certain limit. If the destruction of red blood cells is even faster than this upper production limit, the total number of red blood cells in this patient will decline over time, leading to serious health complications.

When you have an excessively low number of red blood cells, this is called anemia. While there are many different forms of anemia, like iron-deficiency anemia, in which the body is unable to build red blood cells fast enough because it does not get enough iron, the kind where accelerated destruction of red blood cells causes the number of red blood cells to be low, is called hemolytic anemia. This literally means “blood-dissolving” anemia.

Hemolytic anemia has many different causes. The causes fall into two main categories: inherited and acquired.

Hereditary (inherited) hemolytic anemia can be caused by problems with the red blood cells themselves and this is thought to be caused by “intrinsic” factors. Sickle cell anemia and thallasemia are examples of intrinsic hereditary anemias, where the protein hemoglobin, which transports oxygen and gives the red blood cells their red color, is produced in a faulty way.

Other inherited factors that can make red blood cells die faster, are problems with their cell membrane or problems in their cellular metabolism. Unlike other cells in the body, red blood cells rely solely on a metabolic process called glycolysis for energy production, so deficiencies of enzymes involved in this process can cause problems that lead to inherited hemolytic anemia. These problems can for example be caused by inherited glucose-6-phosphate dehydrogenase deficiency or pyruvate kinase deficiency.

Acquired hemolytic anemia can be caused by certain drugs, such as drugs that inhibit glucose-6-phosphate dehydrogenase, increased activity of the spleen, which can be caused by conditions like portal hypertension ( a condition caused by liver cirrhosis), extensive burns and certain infections.

Another important form of hemolytic anemia is called autoimmune hemolytic anemia. In this disease, the immune system, the body’s defense system against foreign intruders like bacteria, viruses and parasites, mistakes the red blood cells for a pathogen, and attacks and destroys them.

This kind of autoimmune destruction can be found as an isolated disease or, more commonly, as a symptom of other diseases like systemic lupus erythematosus or chronic lymphocytic leukemia in which certain proteins of the immune system called antibodies bind to the red blood cells and signal their destruction. Hemolytic anemia can cause a number of health problems down the road like gallstones, pulmonary hypertension (high blood pressure in the lung), and heart failure.

Signs and symptoms of autoimmune hemolytic anemia

Like all anemias, autoimmune hemolytic anemia causes symptoms of oxygen deprivation to all the cells of the body. The most noticeable signs of this condition are shortness of breath and fatigue. Pallor (very pale skin) is also a common sign of anemia. Decreased red blood cell counts are what define anemias.

Another symptom of anemias that is frequently seen in the blood cells is immature red blood cell precursors from the bone marrow that are called reticulocytes. These do not normally show up in large numbers in the blood of healthy people, but they can be seen in people with chronic anemias, as the bone marrow tries to compensate for the increased red blood cell destruction by increasing their production. In children, this activation and expansion of the bone marrow can even lead to changes in the bone structure that are visible on X-rays.

In healthy people, aging red blood cells have increasing amounts of a molecule on the outside that signals to the spleen cell that the red blood cells are becoming old. The spleen cells then remove the red blood cells from the bloodstream without releasing any of their contents into the blood. Since in autoimmune hemolytic anemia the red blood cells disintegrate in the bloodstream, a lot of their contents can be found in the blood e.g. hemoglobin and hemoglobin breakdown products like bilirubin.

The accumulation of bilirubin and other hemoglobin breakdown products in the blood can be seen as jaundice. Large amounts of bilirubin will be excreted by the liver into the bile ducts, which can cause gallstones. The kidneys also excrete higher than usual amounts of bilirubin and other hemoglobin breakdown products, which can cause the urine to become dark brown. Free hemoglobin in the blood is a risk factor for pulmonary hypertension that can lead to right heart failure, edema (water accumulation), mainly in the lower extremities, and even death.
 

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Treatment of autoimmune hemolytic anemia

The main goals of any treatment for hemolytic anemia are:

• To stop or at least decrease the abnormal destruction of red blood cells and to increase the red blood cell counts to more normal levels in order to improve the patient's overall health.
• In the case of autoimmune hemolytic anemias, it is vital to treat the underlying condition. For example, in the case of chronic lymphocytic leukemia or systemic lupus erythematosus, those conditions must be managed well to treat the anemia. If the anemia is so severe that it is life-threatening, a blood transfusion might be necessary to treat the immediate symptoms.

Plasmapheresis is a procedure that removes antibodies from the patient's bloodstream. This unusual procedure can help reduce the rate at which the body breaks red blood cells down as certain autoantibodies bind to the outside of the red blood cells and causes them to be either attacked by another defense system or removed by specialized immune cells called macrophages.

In some cases of autoimmune hemolytic anemia, the offending autoantibodies bind to the red blood cells only in cold temperatures. These are called cold-reactive antibodies. It can be a useful treatment for this condition to avoid cold temperatures and especially to keep fingers, toes, ears, and forehead warm and protected.

Diagnosis is the first step to treatment, and any person with symptoms of anemia should seek prompt medical attention to get to the bottom of the problem and to begin the right treatment, in accordance with the doctor's recommendations.