Anemia Caused by Chronic Diseases
Some chronic (long-term) illnesses can cause anemia. Often, anemia caused by chronic diseases goes undetected until a routine test such as a complete blood count (CBC) reveals abnormal results. Several follow-up tests may be used to determine the underlying cause. There are many chronic conditions and diseases that can result in anemia. Some examples of these include:
- Kidney disease—red blood cells are produced by the bone marrow in response to a hormone called erythropoietin, made primarily by the kidneys. Chronic kidney disease can cause anemia resulting from too little production of this hormone; the anemia can be treated by giving erythropoietin injections.
- Anemia of chronic disease—whenever there are chronic diseases that stimulate the body's inflammatory response, the ability of the bone marrow to respond to erythropoietin is decreased, mainly due to impairment in body iron regulation. For example, rheumatoid arthritis (a severe form of joint disease caused by the body attacking its own joints, called an autoimmune disease) can cause anemia by this mechanism. Other diseases that can produce anemia in the same way include chronic infections such as HIV or tuberculosis (TB).
A number of tests may be used as follow up to abnormal results of initial tests such as a CBC and blood smear to determine the underlying cause of chronic anemia. Some of these may include:
- Reticulocyte count—will typically be low
- Comprehensive metabolic panel (CMP)—used to detect evidence of chronic disorders
Tests for anemia of chronic disease may include:
- Tests for inflammation such as CRP
- Erythropoietin—is typically mildly increased
- Tests for infections such as HIV and TB
- Iron and transferrin (TIBC)—are typically both low
- Soluble transferrin receptor (sTfR)—is typically normal or low
Treatment of anemia due to chronic conditions usually involves determining and/or resolving the underlying disease. Blood transfusions may be used to treat the condition in the short term.