Anemia of inflammation and chronic disease is caused by red blood cells not functioning normally, so they cannot absorb and use iron efficiently. In addition, the body cannot respond normally to erythropoietin (EPO), a hormone made by the kidneys that stimulates bone marrow to produce red blood cells. Over time, this abnormal functioning causes a lower than normal number of red blood cells in the body.
                
Some of the chronic diseases that lead to AI/ACD include infectious and inflammatory diseases, kidney disease, and cancer. Certain treatments for chronic diseases may also impair red blood cell production and contribute to AI/ACD.
                
Infectious and inflammatory diseases. As part of the immune system response that occurs with infectious and inflammatory diseases, cells of the immune system release proteins called cytokines. Cytokines help heal the body and defend it against infection. However, they can also affect normal body functions. In AI/ACD, immune cytokines interfere with the bodys ability to absorb and use iron. Cytokines may also interfere with the production and normal activity of EPO.
                
Infectious diseases that cause AI/ACD include
                
- tuberculosis, an infection in the lungs  - HIV/AIDS, an infection that destroys the immune system  - endocarditis, an infection in the heart  - osteomyelitis, a bone infection
                
Sometimes, acute infectionsthose that develop quickly and may not last longcan also cause AI/ACD.
                
Inflammatory diseases that can lead to AI/ACD include
                
- rheumatoid arthritis, which causes pain, swelling, stiffness, and loss of function in the joints  - lupus, which causes damage to various body tissues, such as the joints, skin, kidneys, heart, lungs, blood vessels, and brain  - diabetes, in which levels of blood glucose, also called blood sugar, are above normal  - heart failure, in which the heart cannot pump enough blood to meet the bodys needs  - inflammatory bowel disease (IBD), diseases that cause inflammation and irritation in the intestines
                
IBD, including Crohns disease, can also cause iron deficiency due to poor absorption of iron by the diseased intestine and bleeding from the gastrointestinal (GI) tract.
                
Kidney disease. People with kidney disease can develop anemia for several different reasons. Diseased kidneys often fail to make enough EPO. In addition, kidney disease results in abnormal absorption and use of iron, which is typical of AI/ACD. Anemia worsens as kidney disease advances. Therefore, most people with kidney failure have anemia. Kidney failure is described as end-stage kidney disease, sometimes called ESRD, when treated with a kidney transplant or blood-filtering treatments called dialysis.
                
People with kidney failure can also develop iron deficiency due to blood loss during hemodialysis, a type of dialysis that uses a special filter called a dialyzer to remove wastes from the blood. Low levels of iron and folic acidanother nutrient required for normal red blood cell productionmay also contribute to anemia in people with kidney disease.
                
Cancer. AI/ACD can occur with certain types of cancer, including Hodgkins disease, non-Hodgkins lymphoma, and breast cancer. Like infectious and inflammatory diseases, these types of cancer cause inflammatory cytokines to be released in the body. Anemia can also be made worse by chemotherapy and radiation treatments that damage the bone marrow, and by the cancers invasion of bone marrow.