People with anemia have less than the normal amount of red blood cells. Anemia is further differentiated by the size of the red blood cells that do exist. In normocytic anemia, patients do not have enough red blood cells, but the cells that they do have are of a normal size. In macrocytic anemia, the red blood cells are larger than normal. And in microcytic anemia, the red blood cells are smaller than they should be. Microcytic anemia can be caused by a number of environmental and genetic problems.
Thalassemia
Thalassemia refers to a number of genetic diseases that cause the body to produce abnormal hemoglobin molecules. The hemoglobin molecule includes a heme protein, where oxygen attaches, and four more parts called chains. The adult form of hemoglobin has two alpha chains and two beta chains. In the different types of beta thalassemia, there are not enough beta chains. In the various alpha thalassemias, there are not enough alpha chains. Thalassemia leads to microcytic anemia because not enough normal hemoglobin is made, according to Sir David Weatherall, M.D. in "Williams Hematology."
Lead Poisoning
According to the Centers for Disease Control and Prevention, there are approximately 250,000 American children with abnormally high lead levels in their bloodstream and 24 million housing units that still have lead paint. Children risk developing lead poisoning mainly from housing that has lead paint. Lead affects the stomach, intestines and nervous system. It also causes microcytic anemia because it interferes with the production of heme, resulting in not enough heme being produced. This means there is not enough normal hemoglobin and the result is a microcytic anemia.
Iron-Deficiency Anemia
Dr. Lichtin writes in "The Merck Manual for Healthcare Professionals" that iron-deficiency anemia is usually from the loss of blood. For a premenopausal woman, it is usually due to her menstrual cycles. For men, it is usually from long-term bleeding from the stomach or intestines. This type of bleeding is occult, or hidden. The lab can detect it in a stool sample, because blood will be in the stool. Blood loss can also be the result of some disorder that destroys red blood cells.
Sideroblastic Anemia
Sideroblastic anemia can be hereditary, in which people have problems making the heme part of hemoglobin or have problems metabolizing vitamin B6. However, some people can develop this microcytic anemia from lead poisoning or chronic alcoholism. They have iron, but it is trapped inside the mitochondria, or internal structures, of a cell, as explained by Dr. Charles Linker in "Current Medical Diagnosis & Treatment."
Anemia of Chronic Disease
Anemia of chronic disease develops in people who have a chronic disease such as an autoimmune disease, inflammatory disease, infection or cancer. The anemia develops because of abnormalities in the development of red blood cells, in the metabolism of iron and in the production of erythropoietin, writes Dr. Morey Blinder in "The Washington Manual of Medical Therapeutics." The kidneys normally secrete erythropoietin, a protein that stimulates the production of red blood cells. Red blood cells are initially normal in anemia of chronic disease, but they eventually become microcytic.
References
- Centers for Disease Control and Prevention: Lead
- "Current Medical Diagnosis & Treatment 2010"; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2010
- The Merck Manual for Healthcare Professionals: Iron Deficiency Anemia
- "The Washington Manual of Medical Therapeutics"; Gopa Green, M.D., Ian Harris, M.D., Grace Lin, M.D., Kyle Moylan, M.D.; 2004
- "Williams Hematology"; Marshall Lichtman, M.D., Thomas Kipps, M.D. et al.; 2010
