Anemia - Introduction

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Highlights	Symptoms	Resources
Introduction	Diagnosis	References
Risk Factors	Dietary Factors
Complications	Treatment

Not all chronic diseases involve the inflammatory process and anemia. For example, high blood pressure is a chronic disease, but it does not affect red blood cells.

Treatment-Related Anemia. Anemia can also result from the therapies used to treat conditions. For example, anemia is a common side effect of cancer treatments. Chemotherapy and radiation can impair the bone marrow's production of red blood cells and contribute to the extreme fatigue that many patients experience during cancer therapy. Patients with hepatitis C frequently receive combination therapy of ribavirin and interferon; ribavirin can induce anemia. Hepatitis C also affects many patients with HIV or AIDS. In addition to ribavirin, patients with HIV or AIDS can develop anemia as a result of highly active anti-retroviral therapy (HAART) and, in particular, from the drug AZT.

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Other medications that increase the risk for anemia are certain antibiotics, some antiseizure medications (phenytoin), immunosuppressive drugs (methotrexate, azathioprine), antiarrhythmic drugs (procainamide, quinidine), and anti-clotting drugs (aspirin, warfarin, heparin).

Megaloblastic Anemia

Megaloblastic anemia is the end-product of deficiencies in the B vitamins folate or vitamin B12 (also called cobalamin), or both. Such deficiencies produce abnormally large red blood cells (megaloblastic ) that have a shortened life span. Neurologic problems are also associated with these deficiencies. Several conditions can cause these deficiencies.

Click the icon to see an image of red blood cells seen in megaloblastic anemia.

Causes of Vitamin B12 Deficiency. Conditions that cause vitamin B12 deficiencies include:

Pernicious anemia. Pernicious anemia is an autoimmune disease in which antibodies are tricked into attacking stomach cells. This results in impaired production of intrinsic factor (IF), a compound that is critical for absorption of vitamin B12. Pernicious anemia is diagnosed in about 1% of people over age 60, with women having a higher risk than men.
H. pylori and atrophic gastritis. A 2000 study suggested that the H. pylori bacterium is a player in many cases of vitamin B12 deficiency. These bacteria are not only major culprits in peptic ulcers but also are strongly associated with atrophic gastritis. This condition is a gradual loss of the stomach lining and is a known cause of vitamin B12 deficiency. (Some researchers theorize that H. pylori-induced injuries in the stomach lining may actually be the first step in the destructive process that leads to pernicious anemia.)

Click the icon to see an image of a peptic ulcer.

Complications of gastrointestinal surgery. Surgeries such as stomach bypass or stapling, which remove part or all of the stomach, pose a 15 - 30% chance of causing vitamin B12 deficiencies.
Overgrowth of intestinal bacteria
Tropical sprue (an acquired malabsorption disease occurring in tropical climates)
Overexposure to nitrous oxide

Vitamin B12 deficiency from diet is very rare, since the liver stores over a 3-year supply. It usually does not occur even in alcoholism, vegetarianism, or in malnourished people with kidney failure or cancer. Since animal products are the chief source, however, true vegan vegetarians may need a supplement, fortified food, or appropriate food selection known to contain adequate amounts of this vitamin.

Click the icon to see an image of the benefits of vitamin B12.

Causes of Folate Deficiency. The body stores only about 100 times its daily requirements for folate and can exhaust this supply within about 3 months if the diet is deficient in folate.

Poor diet coupled with alcoholism is the most common cause of folate deficiency. Alcohol abuse not only contributes to malnutrition but also causes chemical changes that can result in lower folate levels.

Any condition that disturbs the small intestine and impairs its absorption ability can cause a deficiency. Such disorders include:

Inflammatory bowel disease
Celiac sprue (a sensitivity reaction to gluten)

Click the icon to see an image of foods that contain gluten.

Parasitic diseases such as giardiasis
Short bowel syndrome

Deficiencies can also arise due to high demand for folic acid caused by conditions such as cancer, pregnancy, severe psoriasis, severe hyperthyroidism, and hemolytic anemia. Some drugs, including Dilantin, methotrexate, trimethoprim, and triamterene, may also hinder folate absorption.

Less Common Anemias
Form of Anemia	Description and Diagnosis	Causes and Risk Factors	Treatments
Aplastic Anemia	Bone marrow fails to produce all types of blood cells. Symptoms in addition to standard anemia are bleeding in mucous membranes and skin, gingivitis, higher risk for infection, and shortness of breath.	Cause is unknown in half the cases. Known causes include hereditary conditions (Fanconi's anemia), viruses (HIV, hepatitis, Epstein-Barr), autoimmune diseases (lupus, rheumatoid arthritis), medications (valproic acid, tacrolimus, azathioprine) or chemicals (benzene, pesticides).	Transfusions, antibiotics, bone marrow or stem cell transplantation, immunosuppressant drugs. (This anemia used to be nearly always fatal, but survival rates now can reach 92% with successful transplants and up to 87% with immunosuppressants.)
Thalassemia	Genetic blood disease caused by a defect in the rate of production of hemoglobin. The two major forms are thalassemia minor and thalassemia major (Cooley's anemia, beta thalassemia). Thalassemia minor is the more common and milder form, in which life span is normal. Thalassemia major can be serious but it is fortunately very rare.	Affects males and females equally. Most common in people of Mediterranean descent, especially Italians and Greeks. Both types of thalassemia are found in an area that extends from northern Africa and southern Europe to Thailand, including Iran, Iraq, Indonesia, and southern China. Thalassemia major is more common in families who intermarry.	Transfusions to supply enough red blood cells to achieve moderate anemia and avoid iron overload are standard approaches for thalassemia major. Investigation ongoing to find alternatives to transfusions. Hydroxyurea may help some patients. Bone marrow transplantation may be needed. No treatment necessary for thalassemia minor.
Hemolytic Anemias: Acquired	Anemia caused by hemolysis (premature destruction of red blood cells). Diagnosis considered when there is marked increase in RBC production by bone marrow.	Autoimmune hemolytic anemia is the primary type, in which antibodies produced by the immune system damage RBCs. Cause unknown or associated with disorders such as systemic lupus erythematosus, lymphoma, and paroxysmal nocturnal hemoglobinuria. Other causes are high exposure to certain metals or chemicals (lead, copper, benzene, naphthalene), snake and insect bites, malaria, transfusions, post-surgical complications, and drugs such as methyldopa. In infants, blood group incompatibility between mother and child or infections in the womb.	Corticosteroids for autoimmune hemolytic anemia. Transfusions beneficial in many cases. An investigational drug, eculizumab, is showing promise in studies for paroxysmal nocturnal hemoglobinuria.
Hemolytic Anemias: Inherited	Hemolysis (premature destruction of RBCs) caused by sphere-shaped RBCs, which have difficulties circulating through the spleen.	Inherited defects include membrane defects, hemoglobin abnormalities, and enzyme deficiencies. Fava beans may trigger symptoms. More likely and more serious in males than females.	Blood transfusions may be necessary for some types of hemolytic anemia. Experimental trials use immune globulin. Removal of the spleen (splenectomy) or bone marrow transplantation may help some patients.
Sideroblastic Anemias	Group of anemias caused by impaired ability of bone marrow to produce normal RBCs. Normal to high iron levels, but iron cannot be used to make hemoglobin. In addition to the standard symptoms of anemia are jaundice, enlarged liver and spleen, fever, headache, loss of appetite, vomiting, and leg sores. Symptoms can be mild. Usually appears in childhood. Infections, trauma, and pregnancy may trigger symptoms.	Inherited or acquired after excessive alcohol use, certain medications, including chloramphenicol, or other disorders, including some cancers and rheumatoid arthritis. More common in the elderly.	Deferoxamine (Desferal) is used to remove iron. Effectiveness is increased when ascorbate is added to the regimen. Folate and pyridoxine are used, but their effectiveness is under question.
Sickle Cell Anemia	Serious, life-threatening, inherited disease. The sickle-shaped, inflexible RBC has impaired ability to squeeze through vessels. Short life span of RBC (10-20 days) causes anemia. In addition to anemia symptoms, joint and bone pain, infections, and heart failure can occur.	Disease occurs in 0.6% and the trait is found in the genetic makeup of 9% of African-Americans. Also occurs in people from India and Spanish-speaking and Mediterranean regions.	Measures to avoid cycling and control pain. Including hydration, hydroxyurea, NSAIDs and narcotic analgesics. Bone marrow transplantation. [See In-Depth Report #58: Sickle-cell disease.]

Click the icon to see an image of red blood cells found in sickle cell anemia.

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Review Date: 01/17/2007
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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