Bone Marrow aplasia
Bone marrow aplasia involves the reduction of stem cells in the bone marrow, which is charged with the production of all the blood cells.
Due to this reduced production by the bone marrow, an intense deficit is caused in the blood, of erythrocytes (red blood cells, charged with transporting oxygen to the tissue), of leukocytes (white blood cells, charged with the defence against infections) and of platelets (charged with avoiding hemorrhages). Bone marrow aplasia characteristically affects these three types of cells (which are derived from the stem cells) but each one can be affected to a varying degree.
Although in the majority of cases (70%) it is not possible to determine the cause of the aplasia, occasionally the development of this disease can be traced to the ingestion of a particular drug, contact with a chemical agent, pesticides, benzene, paint or ionizing radiation or it can be derived from a another viral infection (most commonly hepatitis). The congenital form of the disease, called Faconi's anaemia, causes chromosome alterations that can produce, in addition to bone marrow failure, congenital abnormalities.
The rate of Bone marrow aplasia oscillates between 2 and 6 in a million new cases each year. However, this rate varies greatly depending on region and several countries have a higher than average number of cases.
The symptoms will depend on the intensity of the deficit of the different blood cells. The deficit of red blood cells (anaemia) can cause tiredness, weakness, paleness, dizziness, palpitations, and headaches, although the anaemia can usually be tolerated due to the slow nature of its evolution. Due to the deficit of leukocytes regular oral ulcers and infections can manifest. The deficit of platelets can produce bruising after minimal accidents, gum or nasal bleeding, and more serious hemorrhages in other parts of the body.
The suspected diagnosis can be derived from a blood test to study any of the manifestations mentioned above. The definitive diagnosis can only be confirmed by an examination of the bone marrow, obtained by a puncture of the sternum or the hip bone. In addition, it will be necessary to remove a small cylinder of the hipbone (bone marrow biopsy) in order to study the structure of the bone marrow. These two tests will differentiate bone marrow aplasia from other causes of the reduction of blood cells. Depending on the intensity of the condition bone marrow aplasia is referred to as mild, severe or very severe.
In cases where aetiological agent has been identified, the principal treatment involves removing the causative agent. In patients who are suffering from the symptoms of the disease, the first treatment will be based around a series of support methods with the aim of improving the manifestations. The first step is usually to carry out a transfusion of red blood cells in order to improve the manifestations caused by anaemia. If bleeding is caused by a reduction in the number of platelets, then a transfusion of platelets should be applied. If the patient experiences a fever or infection, it will be necessary to administer antibiotics and if they do not experience anything then enormous preventative care must be taken.
Patients with a less critical form of aplasia could almost be without any symptoms and would not need such support methods. It is possible to use stimulants for the bone marrow with these patients such as androgens (masculine hormone) that can correct the aplasia. However, the androgens should be administered for a prolonged period but they are not always effective and they produce strong side effects and rarely provide a solution for severe bone marrow aplasia. Patients with a less severe form of aplasia should be treated with an immunosuppressant agent called cyclosporine A, which is sometimes combined with anti-thymocyte globulin (more commonly known as ATG), hematopoietic stimulant factors (such as G-CSF) and corticoids. This treatment will help 50-60% of patients to recover, although in a third of all cases the aplasia will reappear after a period of time, meaning that a new cycle of the aforementioned treatment will need to be administered.
The typical treatment for severe and very severe cases of bone marrow aplasia in young patients (younger than 20-30 years old) is a bone marrow transplantation, if a compatible donor exists. Through this method of treatment up to 80% of patients are cured.
For elderly patients, or those who do not have a compatible donor, treatment is based around the administration of anti-thymocyte globulin (ATG), usually accompanied by cyclosporine. These drugs help to heal the aplasia in 50-70% of cases, although relapses and partial responses are not uncommon. In these situations a second cycle of treatment should be applied or a bone marrow transplant should be carried out if a compatible donor can be found.
If you would like more information, please consult the following web page:
• Fanconi's Anaemia, Medline plus