Anemia is a condition in which red blood cells or the hemoglobin (a protein) in red blood cells is abnormally low.
What is going on in the body?
Hemoglobin helps red blood cells carry and deliver oxygen to the rest of the body. The amount of hemoglobin and number of red blood cells can be decreased by many different conditions. Anemia results in a decreased ability of the blood to carry oxygen to the tissues of the body, which often causes symptoms.
What are the causes and risks of the condition?
Because there are different types of anemia, the causes and risks will vary. Some of the causes of anemia may include:
deficiency of certain minerals or vitamins, such as iron, which is called iron deficiency anemia. Anemia due to vitamin B12 deficiency is called pernicious anemia. Lack of folic acid can also cause anemia, which is called megaloblastic anemia.
inherited conditions, such as sickle cell disease, thalassemia, and glucose-6-phosphate dehydrogenase deficiency
autoimmune disorders, conditions in which a person's immune system attacks his or her own body. In this case, the immune system attacks and destroys the red blood cells. Examples of these disorders include autoimmune hemolytic anemia and systemic lupus erythematosus.
drugs or medications, such as alcohol, the antibiotic penicillin, or the high blood pressure drug methyldopa
blood loss, which can occur due to menstruation, injury, surgery, colon cancer, and other conditions
times of rapid growth, during early childhood, for example
kidney failure, such as chronic renal failure
chronic disorders, especially disorders that cause inflammation. Examples are cancer, the infections tuberculosis and HIV, and rheumatoid arthritis. Hormone imbalances, such as a low thyroid hormone level, called hypothyroidism, are another cause. Anemia from these causes is called anemia of chronic disease.
damage to or other problems in the bone marrow. Bone marrow is a type of tissue in the middle of certain bones that makes red blood cells. Cancer, medications, infections, and other conditions can affect the marrow. There are different names for this type of anemia depending on the exact type. Examples include aplastic anemia and myelophthisic anemia.