It is also known as anemia of inflammation.
It is a condition that can be associated with many different underlying disorders, including chronic diseases such as cancer, certain infections, and autoimmune and inflammatory diseases , such as rheumatoid arthritis or lupus.
Anemia is characterized by low levels of circulating red blood cells or hemoglobin (the part of red blood cells that carries oxygen). It is generally a mild or moderate condition.
In mild cases, anemia may not be associated with any symptoms or it may cause fatigue, pale skin, and lightheadedness. The underlying mechanisms that cause chronic anemia are complex and not fully understood.
Signs and symptoms of chronic anemia
Chronic anemia varies in severity from one person to another. Affected individuals can develop a variety of symptoms such as fatigue, pale skin, lightheadedness, shortness of breath, fast heartbeat, irritability, chest pain, and additional findings.
These symptoms can occur in anyone with a comparable degree of anemia. In most cases, the symptoms associated with the underlying disease generally precede the symptoms of mild or moderate anemia.
In rare cases, chronic anemia can be serious and cause more serious complications.
The exact cause of chronic anemia can vary. Generally, several processes occur at the same time. Anemia can be caused by a slight shortening of the normal survival of red blood cells.
Also, the production of red blood cells ( erythropoiesis ) or erythropoietin (a hormone that stimulates the production of red blood cells) can be affected. Red blood cells carry oxygen to the body. The exact cause of chronic anemia may depend on the underlying condition.
For example, cancer cells can secrete certain substances that damage or destroy immature red blood cells.
In some cases, cancer cells or infectious diseases can infiltrate the bone marrow and the soft, spongy material found in long bones where blood cells form.
Researchers have found that people with chronic anemia also have an imbalance in the distribution of iron in the body and cannot use iron to create new blood cells despite having sufficient or high levels of iron stored in their tissues.
Iron is a critical mineral found in every cell in the body and is essential for the body to function and grow properly. This mineral is found in many types of foods, such as red meat, poultry, eggs, and vegetables.
Iron levels must stay in a specific range within the body, otherwise they can cause anemia (due to low functional iron levels) or damage to affected organs (due to abnormally high iron levels in certain tissues).
Iron is needed to make hemoglobin, the part of a red blood cell that carries oxygen.
A key finding in chronic anemia is increased iron uptake and retention within certain cells, leading to reduced amounts of functional iron that is available for hemoglobin production.
Lack of functional iron hinders the development of hemoglobin, which in turn reduces the amount of oxygen delivered throughout the body (anemia).
Researchers believe that the immune system, which remains constantly active in people with chronic diseases, produces substances that influence the development, storage and transport of iron within the body.
Cells in the immune system produce cytokines, specialized proteins that stimulate or inhibit the function of other cells of the immune system.
Hepcidin, a hormone produced in the liver that helps regulate the metabolism and transport of iron within the body, plays an important role in the development of chronic anemia.
Researchers believe that a specific cytokine known as interleukin 6 (IL-6) stimulates hepcidin production in most cases, although hepcidin can also be produced in response to inflammation by pathways that do not involve IL-6.
Too much hepcidin causes too much iron to be trapped within cells, reducing the amount of iron available to produce hemoglobin, resulting in anemia.
Most researchers believe that hepcidin is a key factor influencing the development of chronic anemia.
Populations affected with chronic anemia
Chronic anemia affects men and women in equal proportions. People of any age who have a chronic inflammatory condition can potentially develop the condition.
The exact incidence of chronic anemia is unknown, and some researchers believe that it is underreported or often unrecognized. Iron deficiency anemia is believed to be the second most common cause of anemia in the United States.
Iron deficiency anemia is a common condition in which individuals have insufficient levels of iron in the body and cannot produce enough red blood cells to carry oxygen throughout the body.
Iron deficiency anemia can cause a variety of symptoms including fatigue, weakness, pale skin, shortness of breath, headaches, and lightheadedness.
Additional symptoms that can occur in people with iron deficiency anemia include cold hands or feet, irritability, irregular heartbeat, and an increased susceptibility to developing infections.
Iron deficiency anemia is caused by insufficient levels of iron in the body, which can occur due to blood loss, a diet that supplies little iron, or the inability to absorb sufficient amounts of iron from the gastrointestinal tract.
Chronic anemia and iron deficiency anemia can be confused because both are associated with decreased circulating iron.
The anemia seen in chronic kidney disease is usually caused by erythropoietin deficiency as a result of kidney cell damage.
However, some patients with kidney disease also have inflammation or infections, and chronic anemia can be part of their anemia.
The diagnosis of chronic anemia is based on the identification of characteristic symptoms, a detailed history of the patient, a thorough clinical evaluation, and a variety of specialized tests.
Such tests can measure levels of certain substances in the body, including hemoglobin levels, serum iron levels, total iron-binding capacity, global red blood cell count, or normal or increased levels of ferritin in the blood.
Ferritin is a protein that binds to iron and is used as an indicator of the body’s iron stores in blood plasma. Another test that can be performed measures transferrin saturation.
Transferrin is a protein that participates in the transport of iron from the intestines to the bloodstream.
Methods have been developed to allow reliable measurement of hepcidin in plasma, but are not currently available or approved for use in the diagnosis of anemia of chronic disease.
Standard therapies for chronic anemia
Treatment of chronic anemia is directed at the underlying disease. If the treatment of the underlying disease is successful, the anemia usually improves or resolves completely without its direct treatment.
Efforts to treat anemia by correcting the iron imbalance in the body with therapies such as oral iron supplements or vitamins have generally been shown to be ineffective.
In fact, such efforts can have a negative impact on overall health. For example, iron supplementation is controversial because certain diseases, such as cancer, use iron to grow and spread, and certain infections use iron for food.
More research is needed to understand the complex mechanisms that ultimately result in chronic anemia and what role, if any, traditional therapies for anemia and iron imbalance have in treating affected people.
In rare cases associated with severe anemia, blood transfusions or treatment with medications that stimulate the production of erythropoietin (a hormone that stimulates the production of red blood cells) may be necessary.
However, in some studies, people who take these therapies have been more affected than people who do not. More research is needed to determine the long-term safety and efficacy of such therapies for the treatment of people with chronic anemia.