what is aplastic anemia
The term “anemia” usually refers to a condition in which your blood has a lower than normal number of red blood cells (RBCs). However, some types of anemia, such as aplastic anemia, cause lower than normal numbers of other blood cells, too. Your bone marrow makes stem cells, which develop into the three types of blood cells—RBCs, white blood cells (WBCs), and platelets. (These stem cells are different from embryonic stem cells, which can develop into any type of cell in the body. Embryonic stem cells aren’t found in bone marrow.) RBCs carry oxygen to all parts of your body. They also remove carbon dioxide (a waste product) from your body’s cells and carry it to the lungs to be exhaled. WBCs help your body fight infections. Platelets are blood cell fragments that help your blood clot. They stick together to seal small cuts or breaks on blood vessel walls and stop bleeding. Blood cells have defined lifespans. RBCs live about 120 days, and platelets live about 6 days. There are different types of WBCs with different lifespans. As a result, your body has a constant need for new blood cells, and your bone marrow is always hard at work to meet that demand.
Certain conditions and factors can disrupt your bone marrow’s ability to make healthy new blood cells.
Aplastic anemia is a condition in which your bone marrow is damaged. As a result, your stem cells are destroyed or don’t develop normally. Your body can’t make enough RBCs, WBCs, or platelets. This type of anemia is rare, but it can be fatal. Aplastic anemia can be acquired or inherited. Many times, the cause of the aplastic anemia or the condition that triggers it is unknown.
- Known causes of acquired aplastic anemia include:
- High-dose radiation or chemotherapy. These cancer treatments kill cancer cells, but they also may damage other cells, such as stem cells. When stem cells are damaged, they can’t develop into healthy RBCs, WBCs, and platelets. Aplastic anemia may go away after these cancer treatments are stopped.
- Environmental toxins. Substances such as pesticides, arsenic, and benzene can damage your bone marrow, causing aplastic anemia.
- Certain medicines. Medicines used to treat rheumatoid arthritis and some antibiotics, such as chloramphenicol (which is rarely used in the United States), can damage the bone marrow and cause aplastic anemia.
- Viral infections. Hepatitis, Epstein-Barr virus, parvovirus B-19, human immunodeficiency virus (HIV), mononucleosis, and cytomegalovirus can damage the bone marrow and lead to aplastic anemia.
- Autoimmune diseases. These diseases, such as lupus and rheumatoid arthritis, may cause your immune system to attack its own cells. This can damage bone marrow cells and prevent them from making enough healthy, new blood cells.
Some inherited conditions can damage your stem cells, leading to aplastic anemia. These conditions include Fanconi anemia, Shwachman-Diamond syndrome, dyskeratosis congenita, DiamondBlackfan anemia, and amegakaryocytic thrombocytopenia. Some women may develop mild aplastic anemia during pregnancy. This anemia tends to go away after the baby is born.
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