Aplastic Anemia and MDS: I of IV
The Aplastic Anemia and MDS International Foundation, Inc. observes Awareness Week each December. Aplastic anemia and MDS(myelodysplastic syndromes) are classified as Bone Marrow Failure Diseases (BMFD). These diseases are relatively rare in the US (2 cases per million people per year), with twice as many cases occurring in Asia. Since Asians living in the US do not have increased incidence of the disease, it is suspected that exposure to toxic chemicals in the developing world is the reason for the increased incidence (in epidemiology this term refers to the number of new cases arising in a given time period). It is sometimes difficult for the average lay person to keep up with the explosive changes in science and medicine, so I will occasionally provide a bit of a primer in this blog.
Most of us know that anemia is caused by a lack of red blood cells, which are produced in the body’s bone marrow. Bone marrow is the soft, inner part of bone where stem cells (immature cells) form the white blood cells (WBC) which fight infections, red blood cells (RBC) which deliver oxygen to the body via the blood stream, and platelets which help form clots to stop bleeding. It doesn’t take much imagination to understand that the absence of any of these cells would lead to illness. When you go to the lab for a CBC with diff (Complete Blood Count with differential), the laboratory technologists are studying your blood sample to look for the number of each type of cell, which is reported to your health care provider. Aplastic anemia means the bone marrow is empty of all cells and is an inherited disorder in about 30% of cases. The other 70% of cases are thought to be caused by exposure to toxic chemicals, viruses or drugs. When doctors can not determine the exact cause of a problem it is called idiopathic, which means it has developed spontaneously or has an unknown cause. Idiopathic, like idiosyncrasy, stems from the Greek word idios meaning one’s own. Most of these cases are acquired, which in medicine means a problem you were not born with, but developed at some point in your life. In MDS, the immature stem cells (referred to as blasts) either die in within the bone marrow, crowding out development of healthy cells or enter the blood stream as non-functioning cells. This set of diseases is found more commonly in people over age 60, especially those who have a history of being treated with chemotherapy or radiation therapy, and those who have had exposure to toxic agents such as benzene.
If supportive treatment for BMFD does not work (again, these diseases are caused by failure of the bone marrow to produce blood cells), and blood counts drop to dangerous levels, you may be referred for allogenic stem cell transplantation. Allogenic means the stem cells are taken from one person and transplanted in another. This involves rigorous treatment before and after the transplant in an effort to prevent complications, and is usually only done in people under 55 who are otherwise in good health. Autologous stem cell transplantation means that stem cells from oneself are transplanted back into the body. More on stem cells and clinical trials next time!
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