Anemia of Inflammation
The blood that circulates throughout the body performs a number of critical functions. It delivers oxygen, removes carbon dioxide, and carries life-sustaining nutrients. By acting as the vehicle for long-distance messengers (such as hormones), blood helps the various parts of the body communicate with each other. This is carried out by blood cells, working in partnership with the liquid part of the blood (plasma).
Most of the cells that make up your blood are red blood cells (erythrocytes). White blood cells (leukocytes) – which defend the body against foreign matter such as bacteria, viruses, and fungi – are also present.
Anemia occurs when there aren’t enough healthy red blood cells in the blood. Most anemias are more of a symptom than a disease and can be the result of a variety of health conditions. With any form of anemia, it’s important to find the cause before treatment begins.
Anemia of inflammation, also known as anemia of chronic disease, develops as a result of an ongoing infection or disease. Usually, it does not cause severe anemia. Anemia of inflammation is thought to be the second most common type of anemia, next to iron deficiency anemia. Although anemia of inflammation is most often seen in people who have a chronic disease, it can also appear in young children who only have a simple ear infection. Anemia of inflammation may go unnoticed and untreated because the attention is centered on the disease that is causing it.
In the past, it was believed that anemia of inflammation was associated only with infections such as syphilis and tuberculosis. Over the last 30 years, connections between the condition and inflammatory diseases such as rheumatoid arthritis, connective tissue disorders, chronic infection, trauma, or cancer have also been established.
Although the exact cause of anemia of inflammation is not known, it is related to the effects of chronic inflammatory diseases on the red blood cells. These conditions cause a number of changes in the body’s red blood cells. The lifespan of red blood cells becomes shorter, production of new red blood cells in the bone marrow slows down, and iron is "withheld" so that it cannot be used to make new red blood cells. Normally the body recycles iron from "old" red blood cells and uses it to make new ones. In anemia of inflammation, the body does not recycle iron as easily, so it is "held up" in cells such as macrophages (a type of white blood cell). There is also decreased iron absorption from the intestines. These changes are caused by a protein called hepcidin.
The following are examples of conditions that can cause anemia of inflammation:
- chronic infections (e.g., tuberculosis, lung abscess, and endocarditis)
- autoimmune diseases or diseases with inflammation (e.g., rheumatoid arthritis, lupus, ulcerative colitis, Crohn’s disease, giant cell [temporal] arteritis)
- cancers (e.g., Hodgkin’s disease, lung cancer, breast cancer)
Symptoms and Complications
There is generally a chronic illness or infection present that causes anemia of inflammation, so the symptoms you may experience will vary. The primary condition causing the anemia will have its own set of symptoms. Symptoms of the anemia may include pale skin, lack of energy, fatigue, headache, lethargy (a feeling of "laziness"), shortness of breath during exercise, and light-headedness.
Since anemia of inflammation is a secondary condition resulting from a primary disease, its treatment is often overlooked.
Making the Diagnosis
Anemia of inflammation isn’t usually severe, and symptoms related to the underlying disease often cover up those of the anemia. This can make it more difficult to diagnose.
Accurate diagnosis depends on blood test results such as the following:
- hemoglobin: low
- reticulocyte count: low to normal
- serum ferritin level: normal to elevated
- serum iron: variable
- total iron binding capacity (TIBC): low
- iron saturation: low to normal
A low TIBC and a normal or elevated ferritin level are the most important signs that indicate that anemia of inflammation is present. With inflammation, the level of certain plasma proteins called acute phase proteins is higher in the blood. The increase in these proteins usually leads to an increase in the blood’s sedimentation rate, which is determined by a blood test.
Treatment and Prevention
People with a chronic inflammatory disease should be carefully monitored for anemia so that it can be diagnosed and treated.
In most cases, the type of inflammatory disease or tumour that’s causing the anemia determines the treatment for anemia of inflammation. It is important to find and treat the underlying cause of the anemia. Once all other causes of anemia are ruled out and the inflammation, infection, or other problem is identified and treated, the anemia may improve.
Medications that are a synthetic form of erythropoietin (e.g., epoetin alfa, darbepoetin alfa*) stimulate the bone marrow to produce more red blood cells. They may be recommended if treatment of the underlying condition isn’t effective or possible.
A blood transfusion may be needed if the anemia is severe.
During the treatment of anemia of inflammation, it’s important to consider the possibility of other contributing factors such as chronic blood loss or non-absorption of iron, which may cause more severe anemia. It may be appropriate for a person with anemia to take iron supplements; talk to your doctor before starting iron supplements.
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