Bone Marrow Failure Diseases
Your bone marrow produces the blood cells that circulate in your body. If you have a bone marrow failure disease, your bone marrow stops functioning or begins producing abnormal blood cells. These diseases, while rare, affect thousands of adults and children every year.
Bone marrow failure diseases are potentially life-threatening but not contagious. Exposure to certain chemicals, such as benzene, can cause bone marrow failure, but more often than not the cause cannot be determined for a given patient.
- Red blood cells carry oxygen from the lungs to the body and carbon dioxide back from the body to the lungs. When red cells are affected by disease, symptoms can include anemia, fatigue, weakness, shortness of breath, and headaches.
- White blood cells are the core of our immune system and help us fight infection. Symptoms of low white cell counts include fevers and infections.
- Platelets cause the blood to clot. Patients with low platelet counts may experience spontaneous bruising, nosebleeds, gum bleeding, and excessive menstrual bleeding.
Mild forms of these symptoms are common and do not necessarily mean you have a bone marrow failure disease. A doctor can review your blood cell counts from a simple blood test called a complete blood count (CBC). If abnormalities are detected, the doctor may want to examine your bone marrow through a bone marrow aspiration and/or bone marrow biopsy. Chromosomal studies may also be done in order to arrive at a complete diagnosis.
Bone marrow failure diseases include aplastic anemia (AA), myelodysplastic syndromes (MDS), paroxysmal nocturnal hemoglobinuria (PNH), pure red cell aplasias (PRCA), and sideroblastic anemia.
Aplastic anemia (AA) is a disease in which the bone marrow fails to produce sufficient numbers of blood cells. Typically, patients have low blood counts across all three types of blood cells — red cells, white cells, and platelets. When the bone marrow of these patients is examined under the microscope, it is usually found to be hypoplastic meaning low growth or no growth of stem cells that are the precusors of all blood cells.
AA can appear at any age, but is more commonly diagnosed in children and young adults. It is a rare disease, affecting fewer than 2 people in 1,000,000 in the United States each year. The cause is thought to be an immune response that destroys the bone marrow. AA can also occur when the bone marrow is damaged by chemotherapy, some medications, or exposure to certain toxic substances.
Although the symptoms of AA may vary from person to person and depend on which types of blood cells are affected, it is important to seek treatment as soon as possible. The most common treatment is immunosuppressive therapy with anti-thymocite globulin (ATG) and cyclosporine. Patients with a matched donor may consider bone marrow, stem cell, or cord blood transplantation.
Myelodysplastic syndromes (MDS) is a group of related disorders in which the stem cells produced by the bone marrow are defective, resulting in too few and poorly functioning blood cells. There are several subtypes of MDS, which are defined by the percentage of immature blood cells (blasts) in the blood stream and the presence or absence of chromosome abnormalities in the bone marrow.
The incidence of MDS increases with age, but can occur in children too. In some patients, MDS progresses over time to acute leukemia. The causes of MDS are mostly unknown, but radiation, chemotherapy, and exposure to certain toxic substances are among the known triggers. Symptoms depend on which blood cell types are affected, but nearly half of the people with MDS have no symptoms at the time of diagnosis. MDS is not contagious and, except for rare cases, is not inherited and does not run in families.
Treatments for MDS vary considerably from supportive care for milder forms of the disease to immunosuppressive drug therapy, chemotherapy, or bone marrow or stem cell transplantation for aggressive forms. Recently, drugs have been approved by the FDA for the treatment of all subtypes , which greatly increases patients' options for dealing with MDS.
Paroxysmal Nocturnal Hemoglobinuria
Paroxysmal nocturnal hemoglobinuria (PNH) is a disease in which the bone marrow produces red blood cells with a defective protective layer. The destruction of red blood cells (called hemolysis) that is characteristic of PNH causes the urine to become dark or red in color. This destruction occurs because the blood cells, lacking the necessary protective molecule, are attacked by the patient's immune system.
Patients will commonly have lower white cell and platelet counts with the attendant symptoms of susceptibility to infection and easy bruising. Other symptoms of PNH may include back pain, abdominal pain, and liver failure. A potentially life-threatening complication is the development of blood clots in the veins.
PNH can occur as an isolated disease, but an estimated 30% of patients with aplastic anemia and some patients with MDS will also have PNH. PNH is not inherited.
Treatments for PNH vary depending on the severity of the symptoms that the patient experiences. Transfusions are given when red cell counts decrease, patients with adequate platelet counts who have blood clots may receive blood thinners, and low white cell and platelet counts can be treated with immunosuppressive therapy as in aplastic anemia.
Marrowforums recommends that you order the AA&MDSIF's education materials on aplastic anemia, MDS, or PNH. Their booklets are excellent, and free!
Supportive care for bone marrow failure diseases often includes blood and platelet transfusions to raise blood counts. Regular blood transfusions can lead to a buildup of iron in the body, a serious but treatable condition known as iron overload.
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