Anemia of chronic disease

by Rosemarie Tremblay-LeMay MD FRCPC
March 3, 2022

What is anemia of chronic disease?

Anemia of chronic disease is a type of anemia that develops as a result of another long-standing medical condition that prevents the body from producing a normal amount of red blood cells (RBCs). Conditions that commonly result in anemia of chronic disease include chronic inflammatory diseases, prolonged infections (such as HIV or tuberculosis), kidney disease, and cancer.

What are red blood cells?

Red blood cells (RBCs) are a specialized type of blood cell. RBCs are responsible for carrying oxygen from your lungs to the rest of your body and carrying carbon dioxide back to the lungs. They hold on to oxygen and carbon dioxide using a specialized protein called hemoglobin.

Normal red blood cells

Red blood cells are made in a part of the bone called the bone marrow. As young RBCs mature in the bone marrow, they produce hemoglobin. Your body needs iron in order to make hemoglobin for RBCs. Once this process is complete, the RBCs are released into the bloodstream. Normal, healthy RBCs circulate in the bloodstream for about 120 days before they are removed, and their iron is recycled to make new RBCs.

Extra iron is stored in a specialized protein called ferritin. The amount of ferritin will change as the amount of iron in your body changes. For example, a person with low levels of iron in their body will have low levels of ferritin in their blood.

What is anemia?

Anemia means a decreased amount of hemoglobin in the blood. This can be due to a decrease in the number of RBCs in your blood or a decrease in the amount of hemoglobin in each RBC. Because the body uses oxygen to make energy, a person with anemia has less oxygen in their blood which can make them feel tired or short of breath.

How do these conditions cause anemia of chronic disease?

Most of the conditions that cause anemia do so by lowering the level of a protein called erythropoietin (EPO) in the body. EPO is made by the kidneys and it acts as a signal to tell the bone marrow to make more RBCs. Conditions that cause anemia of chronic disease decrease the amount of EPO made by the kidneys and some can inhibit the response of the bone marrow to EPO, which results in fewer RBCs produced in the bone marrow. Chronic inflammation can also cause anemia by reducing the amount of new iron absorbed from food or how it can be used by the body.

How do doctors test for anemia of chronic disease?

A blood test can be used to test for anemia of chronic disease.  When examined under the microscope the RBCs usually have normal size (normocytic), although in some cases they can be smaller than normal (microcytic). The level of ferritin in the blood will be normal or increased, even if the iron stores are decreased. The other iron tests will help determine if there is also iron deficiency, as both anemia of chronic disease and anemia of iron deficiency can happen at the same time.

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