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Aplastic Anemia

Aplastic anemia is a blood disorder in which the body's bone marrow doesn't make enough new blood cells. It is a rare, but serious disorder. In the United States, about 500-1,000 people develop this type of anemia each year. The disorder is two to three times more common in Asian countries.

Causes

Damage to the bone marrow's stem cells causes aplastic anemia. Bone marrow is a sponge-like tissue inside the bones. It makes stem cells that develop into red blood cells, white blood cells, and platelets. When stem cells are damaged, they don't grow into healthy blood cells.

The cause of the damage can be acquired or inherited. Acquired aplastic anemia is more common, and sometimes it's only temporary. Aplastic anemia that's inherited is rare. In more than half of the people who have aplastic anemia, the cause of the disorder is unknown. Some research suggests that stem cell damage may occur because the body's immune system attacks its own cells by mistake.

Acquired Causes

A number of diseases, conditions, and factors can cause aplastic anemia, including:

  • Toxins, such as pesticides, arsenic, and benzene
  • Radiation and chemotherapy (treatments for cancer)
  • Medicines, such as chloramphenicol (an antibiotic rarely used in the United States)
  • Infectious diseases, such as hepatitis, Epstein-Barr virus, cytomegalovirus, parvovirus B19, and HIV
  • Autoimmune disorders, such as lupus and rheumatoid arthritis

In some cases, cancer from another part of the body can spread to the bone and cause aplastic anemia.

Inherited Causes

Certain inherited conditions can damage the stem cells and lead to aplastic anemia. Examples include Fanconi anemia, Shwachman-Diamond syndrome, dyskeratosis congenita, and Diamond-Blackfan anemia.

Symptoms

Symptoms of Low Blood Cell Counts

Low numbers of red blood cells, white blood cells, and platelets cause most of the signs and symptoms of aplastic anemia.

Red Blood Cells

The most common symptom of a low red blood cell count is fatigue (feeling tired or weak). Not having enough hemoglobin in the blood causes fatigue. Hemoglobin is an iron-rich protein in red blood cells that carries oxygen to the body.

A low red blood cell count also can cause shortness of breath; dizziness, especially when standing up; headache; coldness in your hands or feet; pale skin, gums, and nail beds; and chest pain.

If you don't have enough hemoglobin-carrying red blood cells, your heart has to work harder to circulate the reduced amount of oxygen in your blood. This can lead to arrhythmias, heart murmur, an enlarged heart, or even heart failure.

White Blood Cells

White blood cells help fight infections. Signs and symptoms of a low white blood cell count include fevers, frequent infections that can be severe, and flu-like illnesses that linger.

Platelets

Platelets stick together to seal small cuts on blood vessel walls and stop bleeding. People who have low platelet counts tend to bruise and bleed easily, and the bleeding may be hard to stop.

Common types of bleeding linked to a low platelet count include nosebleeds, bleeding gums, pinpoint red bleeding spots on the skin, and blood in the stool. Women also may have heavy menstrual bleeding.

Other Signs and Symptoms

Aplastic anemia can cause signs and symptoms that aren't directly related to low blood cell counts. Examples include nausea (feeling sick to your stomach) and skin rashes.

Paroxysmal Nocturnal Hemoglobinuria

About one-third of people who have aplastic anemia have a condition called paroxysmal nocturnal hemoglobinuria (PNH). This is a red blood cell disorder. Most people who have PNH don't have any signs or symptoms.

If symptoms do occur, they may include:

  • Shortness of breath
  • Swelling or pain in the abdomen or swelling in the legs caused by blood clots
  • Blood in the urine
  • Headache
  • Jaundice (a yellowish color of the eyes or skin)

In people who have aplastic anemia with PNH, either condition can develop first.

Diagnosis

Your doctor will diagnose aplastic anemia based on your medical and family histories, a physical exam, and test results.

Complete Blood Count

Often, the first test used to diagnose aplastic anemia is a complete blood count (CBC). The CBC measures many different parts of your blood.

This test checks your hemoglobin and hematocrit levels. Hemoglobin is an iron-rich protein in red blood cells that carries oxygen to the body. Hematocrit is a measure of how much space red blood cells take up in your blood. A low level of hemoglobin or hematocrit is a sign of anemia.

The normal range of these levels varies in certain racial and ethnic populations. Your doctor can explain your test results to you.

The CBC also checks the number of red blood cells, white blood cells, and platelets in your blood. Abnormal results may be a sign of aplastic anemia, an infection, or another condition.

Finally, the CBC looks at mean corpuscular volume (MCV). MCV is a measure of the average size of your red blood cells. The results may be a clue as to the cause of your anemia.

Reticulocyte Count

A reticulocyte count measures the number of young red blood cells in your blood. The test shows whether your bone marrow is making red blood cells at the correct rate. People who have aplastic anemia have low reticulocyte levels.

Bone Marrow Tests

Bone marrow tests show whether your bone marrow is healthy and making enough blood cells. The two bone marrow tests are aspiration and biopsy.

Bone marrow aspiration may be done to find out if and why your bone marrow isn't making enough blood cells. For this test, your doctor removes a small amount of bone marrow fluid through a needle. The sample is examined under a microscope to check for faulty cells.

A bone marrow biopsy may be done at the same time as an aspiration or afterward. For this test, your doctor removes a small amount of bone marrow tissue through a needle.

The tissue is examined to check the number and types of cells in the bone marrow. In aplastic anemia, the bone marrow has a lower than normal number of all three types of blood cells.

Treatment

Treatments for aplastic anemia include blood transfusions, blood and marrow stem cell transplants, and medicines. These treatments can prevent or limit complications, relieve symptoms, and improve quality of life.

Blood Transfusions

People who have aplastic anemia may need blood transfusions to keep their blood cell counts at acceptable levels. A blood transfusion is a common procedure in which blood is given to you through an intravenous (IV) line in one of your blood vessels. Transfusions require careful matching of donated blood with the recipient’s blood. Blood transfusions help relieve the symptoms of aplastic anemia, but they’re not a permanent treatment.

Blood and Marrow Stem Cell Transplants

A blood and marrow stem cell transplant replaces damaged stem cells with healthy ones from another person (a donor). During the transplant, which is like a blood transfusion, you get donated stem cells through a tube placed in a vein in your chest. Once the stem cells are in your body, they travel to your bone marrow and begin making new blood cells.

Blood and marrow stem cell transplants often cure aplastic anemia in people who are eligible for this type of transplant. The transplant works best in children and young adults with severe aplastic anemia who are in good health and who have matched donors. Older people may be less able to handle the treatments needed to prepare the body for the transplant. They’re also more likely to have complications after the transplant.

Medicines

If you have aplastic anemia, your doctor may prescribe medicines to:

  • Stimulate your bone marrow
  • Suppress your immune system
  • Prevent and treat infections

Medicines To Stimulate Bone Marrow

Man-made versions of substances that occur naturally in the body can stimulate the bone marrow to make more blood cells. Examples of these types of medicines include erythropoietin and colony-stimulating factors. These medicines have some risks. You and your doctor will work together to decide whether the benefits of these medicines outweigh the risks. If this treatment works well, it can help you avoid the need for blood transfusions.

Medicines To Suppress the Immune System

Research suggests that some cases of aplastic anemia may occur because the body’s immune system attacks its own cells by mistake. For this reason, your doctor may prescribe medicines to suppress your immune system. These medicines can allow your bone marrow to start making blood cells again. These medicines also may help you avoid the need for blood transfusions.

Medicines that suppress the immune system don’t cure aplastic anemia. However, they can relieve its symptoms and reduce its complications. These medicines often are used for people who aren’t eligible for a bone and marrow stem cell transplant or who are waiting for a transplant.

Three medicines—often given together—can suppress the body’s immune system. They are antithymocyte globulin (ATG), cyclosporine, and methylprednisolone. It may take a few months to notice the effects of these medicines. Most often, as blood cell counts rise, symptoms lessen. Blood cell counts in people who respond well to these medicines usually don’t reach normal levels. However, the blood cell counts often are high enough to allow people to do their normal activities.

People who have aplastic anemia may need long-term treatment with these medicines.

Medicines that suppress the immune system can have side effects. They also may increase the risk of developing leukemia or myelodysplasia (MDS). Leukemia is a cancer of the blood cells. MDS is a condition in which the bone marrow makes too many faulty blood cells.

Medicines To Prevent and Treat Infections

People who have aplastic anemia may be at risk for infections due to a low number of white blood cells. Your doctor may prescribe antibiotic and antiviral medicines to prevent and treat infections.

 

Source

National Heart, Lung, and Blood Institute, USA.