What Is Aplastic Anemia?

Aplastic anemia (a-PLAS-tik uh-NEE-me-uh) is a blood disorder in which the body's bone marrow doesn't make enough new blood cells. 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 (PLATE-lets).

Red blood cells carry oxygen to all parts of your body. They also carry carbon dioxide (a waste product) to your lungs to be exhaled. White blood cells help your body fight infections. Platelets are blood cell fragments that stick together to seal small cuts or breaks on blood vessel walls and stop bleeding.

It's normal for blood cells to die. The lifespan of red blood cells is about 120 days. White blood cells live less than a day. Platelets live about 6 days. As a result, your bone marrow must constantly make new blood cells.

If your bone marrow can't make enough new blood cells, many health problems can occur. These problems include irregular heartbeats called arrhythmias (ah-RITH-me-ahs), an enlarged heart, heart failure, infections, and bleeding. Severe aplastic anemia can even cause death.

Aplastic anemia is a condition that occurs when your body stops producing enough new blood cells. Aplastic anemia leaves you feeling fatigued and with a higher risk of infections and uncontrolled bleeding.

A rare and serious condition, aplastic anemia can develop at any age. Aplastic anemia may occur suddenly, or it can occur slowly and get worse over a long period of time. Treatment for aplastic anemia may include medications, blood transfusions or a stem cell transplant.

Symptoms

Aplastic anemia symptoms may include:
• Fatigue
• Shortness of breath with exertion
• Rapid or irregular heart rate
• Pale skin
• Frequent or prolonged infections
• Unexplained or easy bruising
• Nosebleeds and bleeding gums
• Prolonged bleeding from cuts
• Skin rash
• Dizziness
• Headache

Aplastic anemia can progress slowly over weeks or months, or it may come on suddenly. The illness may be brief, or it may become chronic. Aplastic anemia can be very severe and even fatal.

Causes

Aplastic anemia develops when damage occurs to your bone marrow, slowing or shutting down the production of new blood cells. Bone marrow is a red, spongy material inside your bones that produces stem cells, which give rise to other cells. Stem cells in the bone marrow produce blood cells — red cells, white cells and platelets. In aplastic anemia, the bone marrow is described in medical terms as aplastic or hypoplastic — meaning that it's empty (aplastic) or contains very few blood cells (hypoplastic).

Factors that can temporarily or permanently injure bone marrow and affect blood cell production include:

• Radiation and chemotherapy treatments. While these cancer-fighting therapies kill cancer cells, they can also damage healthy cells, including stem cells in bone marrow. Aplastic anemia can be a temporary side effect of these treatments.

• Exposure to toxic chemicals. Exposure to toxic chemicals, such as some used in pesticides and insecticides, may cause aplastic anemia. Exposure to benzene — an ingredient in gasoline — also has been linked to aplastic anemia. This type of anemia may get better on its own if you avoid repeated exposure to the chemicals that caused your initial illness.

• Use of certain drugs. Some medications, such as those used to treat rheumatoid arthritis and some antibiotics, can cause aplastic anemia.

• Autoimmune disorders. An autoimmune disorder, in which your immune system begins attacking healthy cells, may involve stem cells in your bone marrow.

• A viral infection. Viral infections that affect bone marrow may play a role in the development of aplastic anemia in some people. Viruses that have been linked to the development of aplastic anemia include hepatitis, Epstein-Barr, cytomegalovirus, parvovirus B19 and HIV.

• Pregnancy. Aplastic anemia that occurs in pregnancy may be related to an autoimmune problem — your immune system may attack your bone marrow during pregnancy.

• Unknown factors. In many cases, doctors aren't able to identify the cause of aplastic anemia. This is called idiopathic aplastic anemia.

Risk factors

Aplastic anemia is rare. Factors that may increase your risk include:
• Treatment with high-dose radiation or chemotherapy for cancer
• Exposure to toxic chemicals
• The use of some prescription drugs — such as chloramphenicol, which is used to treat bacterial infections, and gold compounds used to treat rheumatoid arthritis
• Certain blood diseases, autoimmune disorders and serious infections
• Pregnancy, rarely