Anemia of Chronic Disease (Anemia of Inflammation)

What happens in anemia of inflammation

When the immune system is chronically active, it releases inflammatory signals such as interleukin-6. These cause the liver to make hepcidin, the hormone that controls iron. High hepcidin:

• locks iron inside storage cells and the gut lining, so little reaches the bone marrow
• reduces absorption of iron from food

At the same time, inflammation shortens red cell lifespan and blunts the marrow's response to erythropoietin (EPO), the kidney hormone that drives red cell production. The result is a mild, slowly developing anemia. It is the second most common type of anemia after iron deficiency and the most common in hospitalized patients and older adults.

Causes

• Autoimmune and inflammatory diseases: rheumatoid arthritis, lupus, inflammatory bowel disease, vasculitis.
• Chronic infections: HIV, tuberculosis, osteomyelitis, endocarditis, chronic abscesses.
• Cancer: solid tumors and blood cancers.
• Chronic kidney disease: adds a shortage of EPO. See anemia due to chronic kidney disease.
• Heart failure, COPD, diabetes and obesity, which involve low-grade inflammation.
• Aging: many older adults have unexplained mild anemia with an inflammatory pattern.

Symptoms

Anemia of chronic disease often causes no symptoms of its own and is found on blood tests. When present, symptoms include:

• tiredness and low energy
• weakness and reduced exercise tolerance
• shortness of breath on exertion
• pale skin
• dizziness and headaches

These overlap with symptoms of the underlying disease, so it can be hard to tell which is causing what.

How it is diagnosed

A complete blood count shows low hemoglobin, with red cells usually normal-sized (normocytic) or slightly small. Iron studies show the characteristic pattern:

Ferritin rises with inflammation, so a "normal" ferritin can hide true iron deficiency. Doctors often use a higher cutoff (around 100 ng/mL) to suspect combined iron deficiency in people with inflammation. Both conditions frequently occur together, for example in inflammatory bowel disease with bleeding.

Other tests look for the underlying cause: inflammation markers (CRP, ESR), kidney function, and sometimes vitamin B12 and folate levels.

Treatment

Treat the underlying condition

This is the most effective approach. Controlling rheumatoid arthritis, IBD or an infection often lets hemoglobin recover within weeks to months.

Iron

Oral iron is poorly absorbed when hepcidin is high and often does not help. Intravenous iron bypasses the gut and is used when iron deficiency coexists, in chronic kidney disease, in IBD and in heart failure.

Erythropoiesis-stimulating agents (ESAs)

Injections such as epoetin or darbepoetin stimulate red cell production. They are used mainly in chronic kidney disease and in some people having chemotherapy. Targets are kept modest because aiming for normal hemoglobin increases the risk of stroke, clots and heart problems.

Blood transfusion

Reserved for severe or symptomatic anemia, or before surgery.

Taking iron supplements without testing is not recommended, as extra iron can build up when the body cannot use it.

Outlook

The anemia is usually mild and stable and improves when the underlying disease is controlled. Its presence is a marker of active disease, so it is worth investigating and monitoring. Treating it can improve energy and quality of life, particularly in kidney disease and heart failure.

Frequently asked questions

What is anemia of chronic disease?

It is a type of anemia caused by long-lasting inflammation from conditions such as autoimmune diseases, chronic infections, cancer or kidney disease. Inflammation traps iron in storage and slows red blood cell production, causing a usually mild anemia.

How is anemia of chronic disease different from iron deficiency?

In iron deficiency, the body's iron stores are empty, so ferritin is low. In anemia of chronic disease, iron stores are normal or high but locked away by inflammation, so ferritin is normal or high. The two often occur together.

Can iron tablets fix anemia of chronic disease?

Usually not on their own, because inflammation blocks iron absorption from the gut. If true iron deficiency coexists, intravenous iron is often more effective. Treating the underlying inflammatory disease is the main treatment.

Is anemia of chronic disease serious?

The anemia itself is usually mild. Its seriousness depends on the underlying condition. It can worsen fatigue and heart strain in people with heart or kidney disease, so it is monitored and treated when it causes symptoms.

What ferritin level suggests anemia of chronic disease?

Ferritin is usually normal or raised, often above 100 ng/mL, with low serum iron and low transferrin saturation. Ferritin between 30 and 100 ng/mL in someone with inflammation may mean both conditions are present, and further tests help clarify.