Lack of folic acid can also cause anemia, which is called megaloblastic anemia. In this case, the immune system attacks and destroys the red blood cells. 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.
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. Many cases cannot be prevented. Eating a well-balanced diet can help prevent some cases caused by low levels of vitamins or minerals.