Bone marrow depression is a decrease in the number of blood cells. It may concern the level of red blood cells, white blood cells and / or platelets. Generalized fatigue, weakness, repeated infections and abnormal bleeding can occur. We often talk about idiopathic aplastic anemia because its origin is unknown in a large majority of cases.

Definition of aplastic anemia

Bone marrow aplasia is a pathology of the bone marrow, that is, a disease affecting the place where blood cells are produced. This synthesis is strongly affected, which leads to a decrease in the number of cells in the blood.

As a reminder, there are different types of blood cells: red blood cells (red blood cells), white blood cells (leukocytes) and platelets (thrombocytes). Like all cells, these are naturally renewed. New blood cells are continually being synthesized by the bone marrow from stem cells. In the case of aplastic anemia, the stem cells disappear. 

Consequences of aplastic anemia

The consequences can vary from person to person. The decrease in blood cells can be gradual or sudden, and more or less severe. In addition, the different types of cells are not necessarily impacted in the same way.

It is thus possible to distinguish:

• anemia, a decrease in the number of red blood cells, which play a key role in transporting oxygen in the body;
• leukopenia, a drop in the number of white blood cells involved in the body’s immune defense;
• thrombocytopenia, a drop in the level of platelets in the blood known to be important in the phenomenon of coagulation in the event of injury.

Causes of aplastic anemia

In a large majority of cases, the origin of this pathology of the bone marrow is unknown. We speak of idiopathic aplastic anemia.

Nevertheless, research tends to show that aplastic anemia is the consequence of an autoimmune phenomenon. While the immune system generally destroys pathogens, it attacks healthy cells that are essential for the body to function properly. In the case of aplastic anemia, the immune system destroys the stem cells necessary for the production of new blood cells.

Diagnosis of aplastic anemia

The diagnosis is initially based on a complete blood count (CBC), or complete blood count. A blood test is taken to assess the levels of different types of cells (red blood cells, white blood cells, platelets).

If the levels are abnormal, additional tests may be done to confirm the diagnosis of aplastic anemia. For example :

• a myelogram, a test that involves removing part of the bone marrow for analysis;
• a bone marrow biopsy, a test that removes part of the bone marrow and bone.

People affected by aplastic anemia

Both sexes are equally affected by the disease. It can also occur at any age. However two frequency peaks were observed which are between 20 and 25 years and after 50 years.

This pathology remains rare. In Europe and the United States, its incidence (number of new cases per year) is 1 per 500 people and its prevalence (number of subjects affected by the disease in a given population at a given time) is 000 in every 1.

This pathology of the bone marrow can be characterized by a decrease in the blood level of red blood cells (anemia), white blood cells (leukopenia) and / or platelets (thrombocytopenia). Symptoms of aplastic anemia depend on the types of blood cells affected.

Generalized fatigue and weaknesses associated with anemia

Anemia is characterized by a deficit of red blood cells. It can cause symptoms such as:

• paleness of the skin and mucous membranes;
• tiredness ;
• dizziness ;
• shortness of breath;
• palpitations on exertion.

Infectious risk of leukopenia

Leukopenia results in a drop in the number of white blood cells. The body loses its ability to defend itself against attacks from pathogens. Repeated infections can occur at different levels of the body.

Bleeding due to thrombocytopenia

Thrombocytopenia, or a decrease in the number of platelets, affects the phenomenon of coagulation. Bleeding of varying degrees of intensity may appear. They can result in:

• bleeding from the nose and gums;
• bruises and bruises that appear for no apparent cause.

The management of aplastic anemia depends on its evolution. While simple medical supervision can sometimes be sufficient, treatment is necessary in the majority of cases.

In the current state of knowledge, two therapeutic options can be considered to treat aplastic anemia:

• an immunosuppressive treatment which is based on drugs capable of inhibiting the immune system in order to limit, or even stop, the destruction of stem cells;
• bone marrow transplant, which involves replacing diseased bone marrow with healthy bone marrow taken from an accountable donor.

While a bone marrow transplant is currently the most effective treatment for aplastic anemia, this operation is only considered under certain conditions. It is a heavy treatment which is not without risk of postoperative complications. In general, bone marrow transplantation is reserved for patients under 40 years of age with severe form of bone marrow aplasia.

Supportive treatments may be offered to manage the symptoms of aplastic anemia. For example :

• antibiotics to prevent or treat certain infections;
• red blood cell transfusions in case of anemia;
• platelet transfusions in thrombocytopenia.

To date, no preventive measure has been identified. In the majority of cases, the cause of aplastic anemia is unknown.