What are the other Names for this Condition? (Also known as/Synonyms)

• Idiopathic Aplastic Anemia

What is Aplastic Anemia? (Definition/Background Information)

• Aplastic Anemia may be described as a disorder of bone marrow failure. The condition is more common in teenagers and young adults
• It is broadly classified into inherited Aplastic Anemia and acquired Aplastic Anemia (a rare disorder)
  • In 75% of the cases, the cause of the acquired form is not identified; hence, it is known as idiopathic Aplastic Anemia
  • In about 25% of the cases of acquired Aplastic Anemia, the cause may be known
• Bone marrow is the soft and yellow (fatty) tissue located in the center of a bone. The blood cells are formed by stem cells located in the bone marrow. The three major types of blood cells are RBCs (red blood cells), WBCs (white blood cells), and platelets
• In Aplastic Anemia, these stem cells are destroyed, due to which the production of all three blood cell types are affected, leading to a decreased count of blood cells (known as pancytopenia)
• In the majority of cases, the risk factors for Aplastic Anemia are not very well known. The exact cause for most cases are also not well understood. Some researchers believe that the immune system may be involved
• Fatigue, weakness, pale skin, and shortness of breath are some of the common signs and symptoms of Aplastic Anemia. The condition may be typically diagnosed with a blood test such as a complete blood count test
• The treatment of Aplastic Anemia generally focuses on improvement of the symptoms; the prognosis is reported to be favorable in most cases. However, if left undiagnosed/untreated, Aplastic Anemia can even lead to heart failure and severe life-threatening infections

Who gets Aplastic Anemia? (Age and Sex Distribution)

• Aplastic Anemia can affect individuals of any age group; nevertheless, the condition is more common among children, teens, and older adults
• Both males and females are affected equally, and no gender preference is noted
• Worldwide, all racial communities and ethnic groups may be affected, although the condition is more prevalent in individuals of Asian heritage

What are the Risk Factors for Aplastic Anemia? (Predisposing Factors)

In a majority of individuals diagnosed with Aplastic Anemia, the risk factors are unknown or remain unidentified. However, in a few cases, the following may increase one’s risk for the same:

• A family history of the condition
• Exposure to chemicals such as benzene, insecticides, and pesticides
• Use of medications such as chloramphenicol, phenylbutazone, carbamazepine, felbamate, phenytoin, quinine and phenylbutazone, among many others
• Infections, especially hepatitis, cytomegalovirus (CMV), and Epstein-Barr (EBV) infections
• High-dose chemotherapy administered to individuals diagnosed with cancer

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one's chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Aplastic Anemia? (Etiology)

Aplastic Anemia is a serious medical condition that affects blood production. For many individuals with the condition, the causative factor is unknown.

• Researchers believe that autoimmune mechanisms may play a major role in the development of Aplastic Anemia. In autoimmune diseases, one's own immunity targets specific cells and tissues in the body causing their destruction
• It is believed that in Aplastic Anemia, the immune cells attack and destroy the bone marrow stem cells
• Medications such as benzene, chloramphenicol, carbamazepine, etc., are believed to activate one's immunity to act against the hematopoietic bone marrow stem cells

Depending on the blood cell count, Aplastic Anemia can be classified as mild, moderate, and severe; with the mild type having the maximum number of blood cells, and severe having the least number of blood cells. 

What are the Signs and Symptoms of Aplastic Anemia?

The signs and symptoms of Aplastic Anemia may slowly develop over a long period of time, or they can manifest in an acute manner. Additionally, the signs and symptoms may depend on the type of blood cells affected:

A decrease in the number of red blood cells (anemia) can result in:

• Fatigue (increased desire to sleep), weakness
• Dizziness, light-headedness
• Shortness of breath, difficulty breathing
• Pale skin
• Chest pain
• Headache

A decrease in the number of white blood cells (leukopenia) can result in:

• Frequent infections
• Life-threatening infections

A decrease in the number of platelets (thrombocytopenia) can result in:

• Easy bruising with minimal trauma
• Bleeding of the gums
• Nosebleeds
• Increased menstrual blood flow
• Spontaneous life-threatening internal bleeding

How is Aplastic Anemia Diagnosed?

The diagnosis of Aplastic Anemia may involve the following:

• A complete physical examination and assessment of symptoms
• An evaluation of medical history to determine the presence of predisposing factors such as:
  • History of cancer and chemotherapy
  • Recent infections
  • Use of certain medications, or exposure to chemicals/toxins           
• Blood tests:
  • Complete blood count (CBC), which may show decrease in the number of RBCs, WBCs, and platelets

• Hemoglobin electrophoresis
• Reticulocyte count test
• Bone marrow biopsy: This test may be necessary to make a definitive diagnosis of Aplastic Anemia. It may reveal an absence of the precursor cells that form all the three blood cell types. It is also done to rule-out other diseases, such as myelodysplastic syndrome (MDS) and paroxysmal nocturnal hemoglobinuria (PNH), which may be associated with Aplastic Anemia
• Bone marrow aspiration and biopsy are usually performed on the pelvic bone. However, this test can also be performed on the breast bone (sternum), or a leg bone (below the knee, above the foot)
• In this procedure, a large hollow needle is inserted through the skin, muscle, tissue and finally into the bone. The doctor uses twisting hand motion to penetrate the bone and push the needle into the bone marrow cavity. The fluid from the bone marrow is then extracted and the needle withdrawn
• The extracted fluid/tissue is sent to the pathologist, who makes a definitive diagnosis. The pathologist may order additional special tests as required
• Additional tests to check for any predisposing factors, as advised by the healthcare provider, may be warranted

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the Possible Complications of Aplastic Anemia? 

The complications of Aplastic Anemia may include: 

• Severe life-threatening internal bleeding (such as in the brain or abdomen)
• Severe infections that may be life-threatening
• Heart failure
• Progression to myelodysplasia or leukemia (a form of blood cancer)

How is Aplastic Anemia Treated?

The initial treatment of Aplastic Anemia is attempted at symptomatic improvement. The methods may include:

• Packed cell volume (blood transfusion) to increase the count of red blood cells, for relief from symptoms of anemia
• Platelet transfusion to counter any active bleeding
• Antibiotics to treat infections
• Removal of known causative factors (such as medications)

Long-term treatment options for Aplastic Anemia may include: 

• Allogeneic bone marrow transplant: This is the most preferred treatment in children and young adults. In this type of bone marrow transplantation, chemotherapy or radiation is used to destroy the abnormal bone marrow cells. These are then replaced by normal bone marrow cells from a donor by injecting them intravenously into the patient's body, where they travel to the bone marrow and begin to produce new blood cells. Ideally, the best match is obtained from identical twins, siblings, or close relatives having the closest genetic makeup of the individual. But, most of the times, the donors are not necessarily related and only a basic compatibility is sought
• Peripheral stem cell transplantation: Another, similar procedure known as peripheral stem cell transplantation is also used to treat Aplastic Anemia. In this procedure, the donor's blood stream is the source of the stem cells, which are intravenously injected into the patient's blood. However, generally better results are obtained with a bone marrow transplant instead of a peripheral stem cell transplant
• Immune suppressive therapy to suppress autoimmune trigger mechanisms: This is the treatment of choice for those who cannot undergo a bone marrow transplant, either due to advanced age or unavailability of a suitable donor. The most common immunosuppressants used are anti-thymocyte globulin and cyclosporine. Although, the therapy is effective in bringing the individual's blood count back to normal or near normal range for longer duration, it is only a temporary measure and needs to be repeated if Aplastic Anemia recurs. Moreover, the individual is still at risk of developing paroxysmal nocturnal hemoglobinuria (PNH), myelodysplasia, or leukemia, as immunosuppressive therapy has no effect in preventing those conditions
• Hematopoietic growth factors: It is used when individuals do not respond to immunosuppressive therapy. The growth factors such as granulocyte-macrophage colony-stimulating factor (GM-CSF), erythropoietin (EPO), and granulocyte-colony stimulating factor (G-CSF) are injected into the bloodstream, to stimulate the production of blood cells. The procedure may assist in increasing the counts

Clinical trial therapy is also a promising procedure for individuals with Aplastic Anemia.

How can Aplastic Anemia be Prevented?

• If the Aplastic Anemia is inherited, there are no methods or guidelines available at the present time for its prevention
• In cases where the cause is an autoimmune response, the triggers have not all been clearly identified. A few causative factors are known. However, linking an affected individual to a particular cause may not be possible
• It is recommended that individuals prone to Aplastic Anemia make small lifestyle adjustments to better handle their condition. For example, listening to one’s body and resting when fatigued has been shown to improve the overall wellbeing of individuals with the condition

Regular monitoring by a healthcare professional is highly recommended.

What is the Prognosis of Aplastic Anemia? (Outcomes/Resolutions)

• The prognosis of Aplastic Anemia depends on the severity of the condition, availability of matched donors, access to tertiary care facilities, and complications arising from bone marrow transplant or immunosuppressive therapy
• With the currently available medical standards, about 8 in10 individuals with Aplastic Anemia are known to recover and get better
• If left untreated, severe cases of Aplastic Anemia may be fatal

Additional and Relevant Useful Information for Aplastic Anemia:

• Around 600-900 people are diagnosed with Aplastic Anemia per year in the US
• The function of the three major blood cells produced in the bone marrow include:
  • RBCs or erythrocytes: They carry and deliver oxygen from the lungs to the tissues, to help them carry out cellular respiration
  • WBCs or leukocytes: These cells fight against infection and also play a role in inflammation
  • Platelets: These cells help in clot formation when there is a bleeding situation