From Noblood

Introduction

Anemia may be defined as having too few red blood cells in the bloodstream, resulting in insufficient oxygen to tissues and organs (hypoxia). It may also be defined in terms of having a low hemoglobin, hematocrit, packed red cell volume, or total blood count. Iron deficiency, poor diet, kidney failure, bone marrow dysfunction, exposure to toxic or radioactive substances, and blood loss are all potential causes of anemia. Other risk factors for anemia include pregnancy, older age, and renal and chronic diseases.

Common Forms of Anemia

Iron deficiency anemia

Iron deficiency anemia occurs when the body lacks mineral iron to produce the hemoglobin it needs to make red blood cells. In general, there are three stages leading from iron deficiency to anemia:

1. There is an insufficient supply of iron and iron stores are depleted in the bone marrow. This stage generally has no symptoms.
2. Iron deficiencies develop and begin to affect hemoglobin production. (Blood tests in such cases reflect low hemoglobin and hematocrit levels.)
3. Hemoglobin production declines to the point where anemia develops.

Iron deficiency anemia is common in women who have heavy menstrual bleeding.

Anemia from blood loss

Anemia associated with blood loss is the direct result of the decrease in circulating red blood cells (RBCs). The average adult has a total blood volume of approximately 5,000 to 6,000 ml (milliliters) and can usually lose 500 ml of blood without serious or lasting effects; but, if the loss reaches 1,000 ml or more, serious acute consequences may result.

As mentioned above, blood loss can be as a result of very heavy menstrual periods. Most women lose about 44 ml of blood per cycle, but some may lose considerably more. Blood loss also occurs during childbirth or during major surgical procedures. Certain health issues may also contribute to iron loss, including chronic bleeding of the gums, hemorrhoids, or cancer of the stomach. In addition, prolonged treatment with certain drugs can cause gastrointestinal bleeding. Parasites can also cause anemia as they take blood and nutrients for themselves that are meant for the human host.

Anemia of chronic disease (ACD)

In anemia of chronic disease, a chronic disorder slows the production of red blood cells, the result of production of proteins called cytokines that interfere with the production of red blood cells.

Chronic disease often leads to anemia, especially in older adults. Conditions such as infections, inflammation, and cancer particularly suppress production of red blood cells in the bone marrow. Since the suppression is usually not severe, anemia develops slowly and is evident only after time.[1]

Megaloblastic anemia, also known as pernicious anemia

Megaloblastic (pernicious) anemia is a rare disorder in which the body does not absorb enough vitamin B12 from the digestive tract, resulting in an inadequate amount of red blood cells (RBCs) being produced. Megaloblastic (pernicious) anemia is more common in individuals of northern European descent. Megaloblastic (pernicious) anemia results from a lack of intrinsic factor in gastric secretions (a substance needed to absorb vitamin B12 from the gastrointestinal tract); vitamin B12 deficiency results.

The inability to make intrinsic factor may be the result of chronic gastritis or the result of a gastrectomy (removal of all or part of the stomach). Megaloblastic (pernicious) anemia may also be associated with type 1 diabetes, thyroid disease, and a family history of the disease. ^[1]

Hemolytic anemia

Hemolytic anemia is a disorder in which the red blood cells are destroyed faster than the bone marrow can produce them. The term for destruction of red blood cells is hemolysis. The condition can be due to a defect within the red blood cells themselves. Intrinsic hemolytic anemias are often inherited, such as sickle cell anemia and thalassemia. These conditions produce red blood cells that do not live as long as normal red blood cells.

In other cases, red blood cells are produced healthy but are later destroyed by becoming trapped in the spleen, destroyed by infection, or destroyed from drugs that can affect red blood cells. The following lists some of the causes of extrinsic hemolytic anemia, also called autoimmune hemolytic anemia:

• Infections, such as hepatitis, cytomegalovirus (CMV), Epstein-Barr virus (EBV), typhoid fever, E. coli, and streptococcus
• Medications, such as penicillin, antimalaria medications, sulfa medications, and acetaminophen
• Leukemia and lymphoma
• Autoimmune disorders, such as systemic lupus erythematous (SLE, or lupus), rheumatoid arthritis, Wiskott-Aldrich syndrome, and ulcerative colitis
• Various tumors

Sometimes hemolytic anemia is temporary and resolves over several months. In other cases it can become chronic, with periods of remission and recurrence. ^[1]

Treatment

While blood transfusion was often the first line of attack in treating severe anemia, there is increasingly a move away from this strategy. D. Spahn wrote in 1999:

"In specific situations with organ dysfunction caused by extreme anemia, transfusion of red blood cells has been shown to be an efficacious treatment. In most of this studies, this was achieved by transfusion of fresh, mostly autologous, red blood cells. Large studies have failed to demonstrate an outcome benefit in liberally transfused patients. In contrast, there is strong evidence that liberal transfusion of red blood cells adversely affects morbidity and mortality in surgical and critically ill patients. Judicious and restrictive use of red blood cell transfusions is thus indicated."^[1]

In treating anemia it is important to identify the cause; any source of bleeding should be identified and treated with hemostatic agents, mechanical occlusion, or surgical intervention if necessary.

Among the most effective tools for correcting anemia are intravenous iron and erythropoietin therapy.

Iron Deficiency: Mild to moderate iron deficiency anemia may be corrected by eating iron-rich foods to restore iron stores to normal levels.

Among the best iron rich foods are:

• Clams
• Tofu
• Beef liver
• Blackstrap molasses
• Raisin bran
• Oysters
• Sirloin steak
• Shrimp
• Black beans
• Chickpeas
• Turkey breast
• Whole wheat bread
• Chicken breast

Patients scheduled for elective surgery should pay special attention to their diet. Food intake may need to be supplemented with iron tablets. Iron taken orally in any form should be supported with folic acid, vitamin B12, and vitamin C (ascorbic acid). Vitamin C enhances iron absorption — orange juice is a good source of vitamin C and should be drunk with iron-rich foods and iron tablets. Tea or coffee can act as an iron blocker and should be avoided with meals or when taking iron tablets.

See also

Wikipedia: Anemia

References