Anaemia of chronic disease – Diagnostics – Overview of Information and Clinical Research

Diagnosing anaemia of chronic disease requires careful testing and attention to the underlying condition that triggers this blood disorder. Healthcare providers use a combination of blood tests, physical examinations, and medical history to identify this form of anaemia and distinguish it from other similar conditions. Understanding when to seek testing and what the diagnostic process involves can help patients feel more prepared and less anxious about their care.

Introduction: Who Should Undergo Diagnostics and When

Anyone who has a long-term illness lasting more than three months should be aware that anaemia of chronic disease might develop as a complication of their condition. This is particularly important for people living with autoimmune diseases, chronic infections, cancer, chronic kidney disease, or heart failure. These conditions create ongoing inflammation in the body, which can interfere with how the body produces and uses red blood cells.^[1]

Most people age 65 and older are at higher risk for developing this condition. Studies show that about 1 million people in the United States in this age group have anaemia of chronic disease. However, anyone with a chronic inflammatory condition can develop it, regardless of age.^[1]

You should consider seeking diagnostic testing if you experience symptoms that persist even when you are not exercising. Common warning signs include feeling very tired or weak to the point where daily activities become difficult, experiencing shortness of breath, noticing your skin is paler than usual, feeling dizzy or faint, having unexplained sweating, or developing frequent headaches. However, not everyone with anaemia of chronic disease will notice symptoms. Some people only feel symptoms during physical activity, while others may have such mild anaemia that they don’t notice anything wrong at all.^[1]

It is particularly important to seek medical attention if you have a known chronic disease and begin experiencing these symptoms. Because anaemia can sometimes be the first sign of a serious illness, identifying its cause becomes very important. Your healthcare provider will want to rule out other conditions and understand whether the anaemia is directly related to your chronic disease or if there is another underlying problem.^[2]

⚠️ Important

If you have a chronic condition and notice new symptoms of fatigue, weakness, or shortness of breath, contact your healthcare provider promptly. Anaemia may worsen your underlying disease or signal that your condition is progressing. Early detection through diagnostic testing allows for timely treatment adjustments that can improve your quality of life and prevent complications.

Classic Diagnostic Methods for Identifying the Disease

Diagnosing anaemia of chronic disease begins with a physical examination and a detailed discussion of your medical history. Your healthcare provider will want to know about any chronic conditions you have, how long you have had symptoms, and what medications you are taking. The physical exam may reveal signs such as pale skin, rapid heartbeat, or other indicators that your body is not getting enough oxygen.^[1]

The most important first step in diagnosis is a blood test called a complete blood count, or CBC. This test measures the number of red blood cells in your blood and how much hemoglobin they contain. Hemoglobin is the iron-rich protein inside red blood cells that carries oxygen throughout your body. In anaemia of chronic disease, both the number of red blood cells and the amount of hemoglobin are lower than normal. Sometimes this test is done as part of a routine examination, which is how many people first discover they have anaemia.^[4]

After a CBC confirms you have anaemia, your doctor will order additional tests to determine what type of anaemia you have. This is critical because anaemia of chronic disease can look very similar to other forms of anaemia, particularly iron-deficiency anaemia. The symptoms and some test results overlap, which can make diagnosis challenging. Your doctor needs to distinguish between these conditions because the treatments are different.^[2]

Several specific blood tests help identify anaemia of chronic disease. A serum iron test measures the amount of iron circulating in your blood. In anaemia of chronic disease, serum iron levels are typically low because inflammation prevents your body from using stored iron properly. A serum ferritin test measures how much iron is stored in your body. This test is particularly helpful because ferritin levels are usually normal or even elevated in anaemia of chronic disease, even though your body cannot access that iron to make red blood cells. In contrast, people with iron-deficiency anaemia have low ferritin levels because their bodies truly lack stored iron.^[5]

Another important test measures transferrin, a protein that carries iron in your blood. Your doctor may also measure total iron binding capacity, or TIBC, which shows how much transferrin is available to transport iron. In anaemia of chronic disease, transferrin and TIBC levels are typically low or normal. In iron-deficiency anaemia, these values are usually high because your body is trying to capture any available iron.^[5]

A reticulocyte count measures young red blood cells that have recently been released from your bone marrow. This test helps your doctor understand how well your bone marrow is producing new red blood cells. In anaemia of chronic disease, the reticulocyte count is usually low, indicating that your bone marrow is not making enough new cells to replace the ones that are dying.^[5]

When examining red blood cells under a microscope, healthcare providers look at their size and color. Early in anaemia of chronic disease, red blood cells typically appear normocytic, meaning they are normal-sized. Over time, they may become microcytic, or smaller than normal. The cells are usually normochromic, meaning they have normal color, though this can vary. This differs from iron-deficiency anaemia, where cells are often smaller and paler.^[7]

In some cases, particularly when the diagnosis is unclear, additional specialized tests may be needed. A test for soluble transferrin receptor, or sTFR, can help identify whether iron deficiency coexists with anaemia of chronic disease. This test is elevated when true iron deficiency is present. Another test measures reticulocyte hemoglobin content, which is low when there is not enough iron available for making new red blood cells, regardless of how much iron is stored in the body.^[5]

Tests to measure inflammation in your body can also support the diagnosis. C-reactive protein and erythrocyte sedimentation rate are markers that become elevated when inflammation is present. These tests help confirm that chronic inflammation is contributing to your anaemia.^[2]

In rare cases where the diagnosis remains uncertain after all these blood tests, your doctor may recommend a bone marrow biopsy. This procedure involves removing a small sample of bone marrow, usually from your hip bone, to examine how well your bone marrow is producing blood cells. This is typically reserved for complex cases where other tests have not provided clear answers.^[7]

⚠️ Important

A serum ferritin level below 100 nanograms per milliliter in someone with inflammation suggests that iron deficiency may exist alongside anaemia of chronic disease. In patients with chronic kidney disease, the cutoff is even higher at 200 nanograms per milliliter. If you have both conditions, taking iron supplements under medical supervision may be helpful. Never take iron supplements without your doctor’s approval, as excess iron can be harmful if you have normal iron stores.

Diagnostics for Clinical Trial Qualification

When patients with anaemia of chronic disease are being considered for participation in clinical trials, the diagnostic requirements often become more detailed and specific. Clinical trials test new treatments and need to ensure that all participants meet precise criteria so that researchers can accurately measure whether the experimental treatment is working.^[9]

The standard blood tests described earlier form the foundation of clinical trial screening. Researchers will require a complete blood count to document the exact hemoglobin level, red blood cell count, and other blood parameters at the start of the trial. Many trials have specific hemoglobin thresholds for enrollment. For example, a trial might only accept patients whose hemoglobin is above 8 grams per deciliter but below a certain upper limit, ensuring that participants have anaemia that is neither too mild nor too severe.^[5]

Clinical trials for anaemia of chronic disease typically require thorough documentation of the underlying chronic condition. This means participants must have confirmed diagnoses of conditions like rheumatoid arthritis, cancer, chronic kidney disease, or chronic infections through appropriate specialized tests. The trial may require recent imaging studies, biopsy results, or laboratory tests specific to your underlying disease to confirm its presence and severity.^[7]

Iron studies become even more important in clinical trial qualification. Researchers need to confirm that participants truly have anaemia of chronic disease rather than simple iron deficiency. Trials will measure serum iron, ferritin, transferrin saturation, and often soluble transferrin receptor levels to characterize each participant’s iron status precisely. Some trials may exclude patients who have both anaemia of chronic disease and significant iron deficiency, while others may specifically study this combination.^[7]

Markers of inflammation are commonly measured in clinical trials for this condition. C-reactive protein and erythrocyte sedimentation rate tests help confirm that chronic inflammation is present and may be measured repeatedly throughout the trial to track changes. Some trials studying new treatments specifically target the inflammatory pathways involved in anaemia of chronic disease, making these measurements crucial for evaluating the treatment’s effectiveness.^[9]

Many clinical trials measure hepcidin, a hormone that plays a central role in how the body regulates iron. In anaemia of chronic disease, hepcidin levels are typically elevated, which blocks iron from being released from storage sites and absorbed from food. Measuring hepcidin helps researchers understand how inflammation affects iron metabolism and whether experimental treatments are working by changing hepcidin levels. This is a more specialized test than those used in routine diagnosis.^[6]

Kidney function tests are often required for trial participation, even if chronic kidney disease is not your primary condition. This is because kidney disease can cause anaemia through different mechanisms, and researchers need to understand how well your kidneys are working. Tests measuring creatinine and calculating estimated glomerular filtration rate, or eGFR, help assess kidney function.^[7]

Some trials require baseline testing of how your body responds to erythropoietin, the hormone that stimulates red blood cell production. This might involve measuring natural erythropoietin levels in your blood or, in some cases, giving a test dose to see how your body responds. This information helps researchers understand whether impaired erythropoietin production or response contributes to your anaemia.^[5]

Clinical trials typically require participants to have stable chronic disease before enrollment. This means your underlying condition should be well-controlled and not actively worsening. Repeat testing over several weeks may be needed to demonstrate that your hemoglobin levels and disease markers are relatively stable. Trials also commonly require recent electrocardiograms to check heart function, as anaemia can affect the heart, and some experimental treatments may have cardiovascular effects.^[9]

Throughout a clinical trial, participants undergo regular monitoring with the same diagnostic tests used for qualification. Blood counts, iron studies, and inflammation markers are typically measured at scheduled intervals to track response to treatment and watch for side effects. This frequent testing helps researchers understand exactly how the experimental treatment affects the body and whether it successfully improves anaemia.^[9]

Prognosis and Survival Rate

Prognosis

The outlook for patients with anaemia of chronic disease largely depends on the underlying condition causing it. Most people with this form of anaemia have a mild version of the condition, and their prognosis is primarily determined by how well their chronic disease can be managed or treated.^[1]

When the underlying chronic disease improves or is successfully treated, the anaemia often improves as well. For example, if someone with rheumatoid arthritis receives treatment that reduces inflammation, their anaemia may lessen as the inflammation decreases. This connection means that treating the root cause of inflammation is the most important factor in improving anaemia of chronic disease.^[4]

However, in situations where the underlying disease cannot be cured or easily controlled, such as with certain cancers or advanced chronic kidney disease, the anaemia may persist or worsen over time. In these cases, the anaemia itself can negatively impact quality of life and survival. Research shows that in chronically ill patients with anaemia, this blood disorder has a negative impact on both quality of life and survival.^[6]

The severity of anaemia also affects prognosis. Mild anaemia may cause minimal symptoms and have little impact on daily life. More severe anaemia, defined as hemoglobin levels below 8 grams per deciliter, can lead to significant complications and may increase the risk of death, particularly in people with heart failure.^[2]

People who develop anaemia of chronic disease in the context of acute infections or inflammation may see complete resolution once the infection is treated or the inflammation subsides. The same inflammatory processes that begin during any infection or trauma can trigger this type of anaemia, but when the triggering event resolves, the anaemia typically improves.^[5]

Survival Rate

Specific survival statistics for anaemia of chronic disease itself are difficult to establish because survival is so closely tied to the underlying condition causing the anaemia rather than the anaemia alone. The condition does not have a distinct survival rate separate from the diseases that cause it.^[6]

What is known is that anaemia can worsen outcomes for people with serious chronic diseases. In patients with heart failure, anaemia may lead to a higher risk of death. The reduced oxygen-carrying capacity of the blood puts additional strain on an already weakened heart, potentially accelerating disease progression.^[2]

In patients with cancer, the presence of anaemia has been associated with poorer outcomes and can complicate cancer treatment. However, distinguishing whether the anaemia itself directly causes worse survival or whether it simply reflects more advanced or aggressive disease can be challenging.^[15]

The good news is that anaemia of chronic disease is treatable, and addressing it can improve how patients feel and function in their daily lives. While the anaemia may not directly determine survival in most cases, reducing symptoms like fatigue and shortness of breath can significantly enhance quality of life, which is an important outcome for people living with chronic conditions.^[4]

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