Anaemia of chronic disease is a condition where long-lasting illnesses cause the body to struggle with making enough healthy red blood cells, even when iron stores may be normal. This type of anaemia develops when ongoing inflammation interferes with how the body uses iron to create the cells that carry oxygen throughout the body.
Understanding Anaemia of Chronic Disease
Anaemia of chronic disease, also known as anaemia of inflammation or anaemia of chronic inflammation, occurs when a person has a long-term illness that lasts longer than three months and causes inflammation in the body. This inflammation disrupts the normal process of making red blood cells, which are essential for carrying oxygen from the lungs to all body tissues. When the body doesn’t have enough red blood cells or when these cells don’t work properly, anaemia develops.[1][3]
What makes this type of anaemia unusual is that the body may actually have normal or even increased amounts of iron stored in tissues, but the inflammation prevents the body from using this iron effectively. The iron gets trapped in certain cells called macrophages, which are part of the immune system. This means that even though iron is present in the body, it becomes unavailable for making new red blood cells, leading to anaemia despite adequate iron stores.[3][8]
Most people who develop anaemia of chronic disease have a mild form of the condition. Healthcare providers focus on treating the underlying chronic illness, as improving the primary disease often helps resolve the anaemia. The condition develops as a result of complex changes in the body triggered by ongoing inflammation, rather than from a simple lack of nutrients or vitamins.[1][4]
Epidemiology: Who Gets This Condition
Anaemia of chronic disease is remarkably common and represents the second most common type of anaemia worldwide, coming right after iron-deficiency anaemia. Among hospitalized patients or those who are critically ill, it becomes even more prevalent and is actually the most common form of anaemia found in these settings.[5][7][12]
The condition shows a clear pattern of affecting older adults more frequently than younger people. Most people who have anaemia of chronic disease are age 65 and older. Studies indicate that approximately 1 million people in the United States who are 65 years and older have this condition. The incidence increases with age, and research shows that it affects about 77 percent of elderly individuals in whom no clear cause of anaemia has been identified, suggesting that multiple factors may contribute to its development in this age group.[1][6]
Anyone who has a chronic illness may develop anaemia of chronic disease, regardless of age. The condition affects patients across different geographic regions, though its exact prevalence can be difficult to pinpoint because it is often confused with iron deficiency anaemia and is typically diagnosed by excluding other possible causes. Among admitted hospital patients, it stands as the most common cause of anaemia, highlighting its significant impact on healthcare systems and patient populations.[6][15]
Causes: Why Chronic Diseases Lead to Anaemia
Anaemia of chronic disease develops when ongoing inflammation from a long-term illness disrupts the body’s normal blood cell production. Any chronic disease that causes inflammation can trigger this type of anaemia. The condition is not infectious and cannot be transmitted from person to person, as it results from the body’s response to an existing disease rather than from a pathogen.[1][4]
Several major categories of chronic diseases commonly cause this type of anaemia. Cancer is one significant cause, including various types such as lymphoma and Hodgkin disease. Chronic infections also play a major role, including long-term bacterial infections like bone infections, lung abscesses, and conditions such as HIV/AIDS, hepatitis B, and hepatitis C. These infections create persistent inflammation that interferes with red blood cell production.[2][5]
Autoimmune diseases represent another important group of conditions that trigger anaemia of chronic disease. In these disorders, the immune system mistakenly attacks the body’s own tissues instead of protecting them. Rheumatoid arthritis, which causes chronic inflammation of the joints, is a particularly common culprit. Systemic lupus erythematosus (or lupus) causes tissue damage throughout the body from immune system attacks. Inflammatory bowel diseases, including Crohn’s disease and ulcerative colitis, which affect the intestines, also frequently lead to this form of anaemia.[1][2]
Other chronic conditions linked to anaemia of chronic disease include chronic kidney disease, heart failure, vasculitis (inflammation of blood vessels), sarcoidosis (an inflammatory disease commonly affecting the lungs and lymph glands), and diabetes. Having obesity is also associated with increased risk of developing this condition. Even irritable bowel syndrome and any type of infection can potentially trigger the inflammatory processes that lead to anaemia of chronic disease.[1][2][4]
Risk Factors: Who Is More Vulnerable
The primary risk factor for developing anaemia of chronic disease is having any chronic illness that causes inflammation. This means that anyone diagnosed with conditions like cancer, chronic kidney disease, autoimmune disorders, or long-term infections faces an increased risk of developing this type of anaemia. The longer a person has one of these inflammatory conditions, the greater the likelihood that anaemia may develop as a complication.[1][3]
Age represents another significant risk factor. Older adults, particularly those aged 65 and above, show much higher rates of anaemia of chronic disease compared to younger populations. This increased vulnerability in elderly individuals occurs partly because chronic diseases become more common with advancing age, and partly because aging itself may affect how the body responds to inflammation and produces blood cells.[1][6]
People with multiple chronic conditions face compounded risk. For example, someone with both diabetes and chronic kidney disease would have greater vulnerability to developing anaemia of chronic disease than someone with just one chronic condition. Similarly, individuals with autoimmune diseases that cause ongoing, active inflammation in their bodies are at particularly high risk. Conditions like rheumatoid arthritis, where inflammation persistently affects the joints and potentially other body systems, create an environment where anaemia of chronic disease commonly develops.[2][4]
Having obesity also increases risk for anaemia of chronic disease, as excess body fat can contribute to chronic low-level inflammation throughout the body. Patients undergoing treatment for cancer or those with end-stage kidney disease requiring dialysis are also at elevated risk. Even acute situations like trauma, critical illness, or the period following surgery can trigger the same inflammatory processes that lead to anaemia, though in these cases it may be temporary rather than chronic.[1][5][11]
Symptoms: How This Condition Affects Daily Life
Many people with anaemia of chronic disease may not notice any symptoms at all, especially when the anaemia is mild. Some individuals only experience symptoms when they’re physically active or exercising, while feeling relatively normal during rest. This can make the condition easy to overlook initially, as people may simply attribute their tiredness to the underlying chronic disease they already have.[1][4]
When symptoms do appear, the most noticeable is feeling very tired or weak. This fatigue can be profound enough that people feel too weak to manage their normal day-to-day activities. Simple tasks that were once easy may suddenly feel exhausting. This happens because red blood cells carry oxygen to all body tissues, and when there aren’t enough healthy red blood cells, the body’s organs and muscles don’t get the oxygen they need to function efficiently.[1][2]
Other common symptoms include feeling short of breath, particularly during physical activity. People may notice their skin appears paler than usual, which occurs because there’s less oxygen-rich blood flowing near the skin’s surface. Some individuals experience dizziness or feel faint, especially when standing up quickly. Headaches can develop as the brain struggles to get enough oxygen. Some people may feel sweaty for no apparent reason, or notice their heart pounding or beating irregularly.[1][2][4]
In more severe cases, people may find it hard to focus and think clearly. The symptoms of anaemia of chronic disease are very similar to those of iron-deficiency anaemia, which is why proper medical testing is essential to distinguish between these conditions. The severity of symptoms often corresponds with how severe the underlying chronic disease is, as well as how low the red blood cell count has dropped.[4][6]
Prevention: Reducing Your Risk
Preventing anaemia of chronic disease primarily focuses on managing and treating the underlying chronic conditions that cause it. When the primary illness is well-controlled, the risk of developing anaemia decreases significantly. For people with autoimmune diseases, following prescribed treatment plans to reduce inflammation can help prevent or minimize anaemia. Similarly, individuals with chronic infections benefit from appropriate antibiotic or antiviral treatments that address the source of inflammation.[1][4]
Regular medical monitoring plays a crucial role in prevention. People with chronic conditions known to cause anaemia of chronic disease should have regular blood tests to check their red blood cell counts and haemoglobin levels. Early detection of declining blood counts allows healthcare providers to intervene before anaemia becomes severe. These routine checks are particularly important for elderly patients and those with multiple chronic conditions.[6]
While there is no specific vaccine or supplement that can prevent anaemia of chronic disease, maintaining overall good health can help. This includes following treatment plans for existing chronic diseases, attending all scheduled medical appointments, and reporting new symptoms promptly to healthcare providers. For people with inflammatory bowel disease or chronic kidney disease, regular monitoring helps identify anaemia early so it can be addressed alongside the primary condition.[7][12]
It’s important to understand that because anaemia of chronic disease results from the body’s response to inflammation rather than from nutritional deficiencies, simply taking iron supplements or eating iron-rich foods will not prevent it if you have normal iron levels. In fact, taking extra iron when your body doesn’t need it can be harmful. Prevention strategies should always be discussed with a healthcare provider who can tailor recommendations to your specific chronic condition and health status.[4][10]
Pathophysiology: How the Condition Develops in the Body
Anaemia of chronic disease develops through several interconnected mechanisms that all stem from the body’s inflammatory response to chronic illness. Understanding these processes helps explain why this type of anaemia is different from other forms and why it requires a different treatment approach. The pathways involved are complex and involve changes in how the body produces red blood cells, uses iron, and responds to signals that normally stimulate blood cell production.[5][11]
One major mechanism involves changes in red blood cell survival. Normally, red blood cells live for about 120 days before they naturally die and get recycled by the body. In anaemia of chronic disease, these cells may die sooner than usual. This shortened lifespan occurs because macrophages, which are immune cells that clean up old or damaged cells, become overly active during inflammation and may destroy red blood cells prematurely through a process called hemophagocytosis. This means red blood cells are being removed from circulation faster than the body can replace them.[1][5][11]
The body’s ability to produce new red blood cells also becomes impaired. Red blood cells are made in the bone marrow, a spongy tissue inside bones. This production process is normally stimulated by a hormone called erythropoietin, which is made by the kidneys. In anaemia of chronic disease, the body doesn’t produce enough erythropoietin, and the bone marrow doesn’t respond properly to the erythropoietin that is produced. Additionally, inflammatory chemicals called cytokines can directly damage developing red blood cells in the bone marrow, causing them to die before they mature. This happens through the formation of harmful molecules called free radicals or through a programmed cell death process called apoptosis.[5][11]
Perhaps the most important mechanism involves disrupted iron metabolism. Iron is essential for making hemoglobin, the protein in red blood cells that carries oxygen. In anaemia of chronic disease, the body has a particular problem with iron availability. When old red blood cells are broken down, the iron they contain is normally recycled to make new red blood cells. However, in chronic disease with inflammation, macrophages trap this recycled iron instead of releasing it back into circulation. This happens because inflammation causes the liver to produce increased amounts of a protein called hepcidin.[3][5][11]
Hepcidin acts like a lock on the door through which iron leaves storage sites and enters the bloodstream. When hepcidin levels are high, iron gets trapped inside macrophages and cannot be released for use in making new red blood cells. Hepcidin also blocks iron absorption from the intestines, further limiting the iron available for red blood cell production. The result is that even though iron may be plentiful in the body’s storage sites, it becomes functionally unavailable where it’s needed most. This creates what doctors call “iron-restricted erythropoiesis,” meaning the process of making red blood cells is restricted by lack of accessible iron, not lack of total iron.[5][6][11]
Several specific inflammatory cytokines drive these changes. These include interleukin-1-beta, interleukin-6, tumor necrosis factor-alpha, and interferon-gamma. These molecules are produced by immune cells in response to infection, cancer, or autoimmune disease. While they serve important functions in fighting disease and coordinating immune responses, they also have the unintended consequence of triggering the changes that lead to anaemia. They signal the liver to make more hepcidin, they suppress erythropoietin production, and they can directly interfere with red blood cell development in the bone marrow.[5][11]
Over time, if the chronic disease persists, the red blood cells may change in appearance. Initially, the red blood cells in anaemia of chronic disease are normocytic, meaning they are normal in size. However, as the condition continues, the cells may become microcytic, meaning smaller than normal. This happens because the lack of available iron means that developing red blood cells cannot make enough hemoglobin to fill themselves properly, resulting in smaller cells with less oxygen-carrying capacity.[5][11]