Aplastic anemia is a blood disorder that begins in the bone marrow where blood cells form. New blood cells start as stem cells. Through several mechanisms, the bone marrow and stem cells can be damaged, creating a deficiency in red blood cells, white blood cells, or platelets. Although aplastic anemia can happen to anyone at any age, it is a rare disorder. A study published by Haematologica in 2017 reports there are approximately 1.5 to seven cases of aplastic anemia per million in a year.
What Happens in the Body?
The bone marrow creates stem cells, which mature into red, white, and platelet cells. Aplastic anemia disrupts the process, and the stem cells don’t mature. The bone marrow is usually comprised of immature stem cells, but in aplastic anemia, fat cells replace stem cells. The deficiency of healthy blood cells can cause severe symptoms and illness.
External Causes
External causes are those that originate outside the body. Radiation and chemotherapy treatment for other types of cancer can damage healthy stem cells, which can temporarily cause aplastic anemia. Exposure to toxic chemicals such as pesticides and benzene has been linked to this condition, as well. Also, there is a link between aplastic anemia and the use of drugs that help treat autoimmune diseases by suppressing bone marrow response.
Internal Causes
Internal causes originate inside the body. Autoimmune disorders that cause the body to attack itself may also attack the bone marrow, leading to aplastic anemia. Viral infections such as Epstein Barr, HIV, cytomegalovirus, hepatitis, and parvovirus B19 may play a role. Doctors have reported minor incidences of aplastic anemia brought on by pregnancy. Some cases of aplastic anemia have unknown causes.
Symptoms
The symptoms of aplastic anemia are related directly to a deficiency in red, white, and platelet blood cells. These symptoms are pale skin, fatigue, shortness of breath, rapid breathing and heart rate, dizziness, headache, bleeding, bruising, infections that don’t heal, low oxygen, and a skin rash called petechiae. Symptoms can come on gradually or suddenly.
Diagnosis
Blood tests and bone marrow biopsy are the primary sources of diagnosis for aplastic anemia. However, other criteria such as chest x-ray, liver scans, viral studies, and immune scans help ensure the correct diagnosis. Blood tests often show a serious deficiency in red, white, and platelet cells but may also show other problems with hemoglobin, blood clotting, liver, kidney, and inflammatory results. Bone marrow biopsy will show fat cells in place of stem cells, which confirms the diagnosis.
Treatments
Treatment for aplastic anemia aims to control the symptoms as well as stop the damage to the bone marrow. In some cases, individuals require stem cell transplants. Blood transfusions of red, white, and platelet cells will provide symptom relief. This is not a long-term solution, as the body may begin to build resistance against the transfused blood. Immunosuppressants help stop this resistance, which makes transfusions easier for the body to accept. Also, immunosuppressant medication can help stop autoimmune damage to the stem cells. Bone marrow stimulants can be helpful, as can antivirals and antibiotics for underlying viral and bacterial infections.
Conditions Related to Aplastic Anemia
Diagnostics can confuse aplastic anemia with a myelodysplastic syndrome that causes deformed or underdeveloped stem cells. Often, this disorder can create more of these blood cells instead of less. Paroxysmal nocturnal hemoglobinuria causes red blood cells to break down too soon but may eventually lead to aplastic anemia. Some blood cancers initially look like aplastic anemia, but further tests usually reveal the correct diagnosis.
Risk Factors
The main risk factor is exposure to radiation or chemotherapy. Exposure to other toxic chemicals may also increase and become a significant risk. Certain prescription drugs such as antibiotics or gold compounds used to treat infections and arthritis may increase risk. Lastly, conditions that cause autoimmune attacks on the body such as rheumatoid arthritis, lupus, or autoimmune blood and liver disorders can increase the risk of aplastic anemia.
Follow-Up and Monitoring
Aplastic anemia requires long term follow up, even after the individual has gone into remission. The disease is somewhat idiopathic, meaning the cause and progression is unclear, and so once a person has it, they may be at risk for getting it again. There’s a link between aplastic anemia and paroxysmal nocturnal hemoglobinuria. Research suggests they may overlap, so many medical professionals continue to monitor former patients to ensure that should the latter condition develop, treatment is responsive and timely.
Prognosis
Without treatment, aplastic anemia is life-threatening. Recent research shows that with treatment, the five-year survival rate is between 70-80% for people under 40. For people over 40, the five-year survival rate is 50%. Survival rates are even higher if the person finds a well-matched stem cell donor. Relapses are common, as is the graft-versus-host disease following transplant treatments. In graft-versus-host, the body attacks new stem cells, causing many medical issues. Therefore, long-term monitoring of aplastic anemia is required.