Anemia

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Description

An in-depth report on the types, diagnosis, treatment, and prevention of anemia.

Alternative Names

Iron deficiency; Pernicious anemia

Highlights

Anemia is the name applied to many different conditions that are all characterized by an abnormally low number of healthy red blood cells. There are many different causes and types of anemia.

Iron-deficiency anemia, the most common type, is usually treated with dietary changes and iron supplement pills. Other types of anemia, such as those associated with chronic diseases or cancer, may need more aggressive treatment.

Preventing Iron Deficiency in Infants and Toddlers

The American Academy of Pediatrics' guidelines for preventing iron deficiency and iron deficiency anemia in infants and young children include:

  • Full-term infants who are healthy and exclusively breastfed should receive an oral iron supplement beginning at 4 months of age. The supplement should be continued until iron-containing solid foods, such as cereals, are introduced. Breast milk itself contains very little iron, but most healthy babies are born with iron stores sufficient for their first 4 months.
  • Preterm infants who are breastfed should receive an iron supplement by 1 month of age.
  • Formula-fed infants get adequate iron from iron-fortified formula. For all babies, cow’s milk should not be introduced before age 12 months.
  • Toddlers ages 1 - 3 years should get their iron from foods such as red meats, iron-rich vegetables, and fruits that are rich in vitamin C. (Vitamin C helps boost iron absorption.)

Anemia Drug for Dialysis Patients Approved and Recalled

In March 2012, the FDA approved the erythropoiesis-stimulating drug peginesatide (Omontys) specifically for patients receiving kidney dialysis. In February 2013, the drug’s manufacturers issued a voluntary recall of the drug due to reports of serious and fatal allergic reactions.

Introduction

Anemia is an abnormal reduction in red blood cells.

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Normal red blood cells (RBCs) as seen in the microscope after staining.

Anemia is not a single disease but a condition, like fever, with many possible causes and many forms. Causes of anemia include nutritional deficiencies, inherited genetic defects, medication-related side effects, and chronic disease. It can also occur because of blood loss from injury or internal bleeding, the destruction of red blood cells, or insufficient red blood cell production. The condition may be temporary or long term, and can manifest in mild or severe forms.

This report focuses on the most common forms of anemia:

  • Iron deficiency anemia
  • Anemia of chronic disease (ACD)
  • Treatment-related anemia (chemotherapy, medication, radiation therapy)
  • Megaloblastic anemia (caused by deficiencies in the B vitamins folate, vitamin B12, or both)

Blood

Blood has two major components:

  • Plasma is a clear yellow liquid that contains proteins, nutrients, hormones, electrolytes, and other substances. It constitutes about 55% of blood.
  • White and red blood cells and platelets make up the balance of blood. The white cells are the infection fighters for the body. Platelets are necessary for blood clotting. The important factors in anemia, however, are red blood cells.

Red blood cells (RBCs), also known as erythrocytes. carry oxygen throughout the body to nourish tissues and sustain life. Red blood cells are the most abundant cells in our bodies. On average, men have about 5.2 million red blood cells per cubic millimeter of blood, and women have about 4.7 million per cubic millimeter of blood.

Hemoglobin and Iron

Each red blood cell contains 280 million hemoglobin molecules. Hemoglobin is a complex molecule, and it is the most important component of red blood cells. It is composed of protein (globulin ) and a molecule (heme ), which binds to iron.

In the lungs, the heme component binds to oxygen in exchange for carbon dioxide. The oxygenated red blood cells are then transported to the body's tissues, where the hemoglobin releases the oxygen in exchange for carbon dioxide, and the cycle repeats.

The oxygen is used in the mitochondria. the power source within all cells.

Red blood cells typically circulate for about 120 days before they are broken down in the spleen. Most of the iron used in hemoglobin can be recycled from there and reused.

Structure and Shape of Red Blood Cells

Red blood cells -- the erythrocytes -- are extremely small and look something like tiny, flexible discs. This unique shape offers many advantages:

  • It provides a large surface area to absorb oxygen and carbon dioxide.
  • Its flexibility allows it to squeeze through capillaries, the tiny blood vessels that join the arteries and veins.

Abnormally shaped or sized erythrocytes are typically destroyed and eliminated.

Blood Cell Production (Erythropoiesis)

The actual process of making red blood cells is called erythropoiesis. (In Greek, erythro means "red," and poiesis means "the making of things.") The process of manufacturing, recycling, and regulating the number of red blood cells is complex and involves many parts of the body:

  • The body carefully regulates its production of red blood cells so that enough are manufactured to carry oxygen but not so many that the blood becomes thick or sticky (viscous).
  • Most of the work of erythropoiesis occurs in the bone marrow. In children younger than 5 years old, the marrow in all the bones of the body is enlisted for producing red blood cells. As a person ages, red blood cells are eventually produced only in the marrow of the spine, ribs, and pelvis.
  • If the body needs more oxygen (at high altitudes, for instance), the kidney triggers the release of the hormone erythropoietin (EPO), a hormone that acts in the bone marrow to increase the production of red blood cells.
  • The lifespan of a red blood cell is 90 - 120 days. The liver and the spleen remove old red blood cells are removed from the blood by the liver and spleen.
  • When old red blood cells are broken down for removal, iron is returned to the bone marrow to make new cells.
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    Causes

    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:

    • First, there is an insufficient supply of iron, which causes iron stores in the bone marrow to be depleted. This stage generally has no symptoms.
    • Second, iron deficiencies develop and begin to affect hemoglobin production. (Tests will show low hemoglobin and hematocrit levels.)
    • Hemoglobin production declines to the point where anemia develops.

    Most of the iron used in the body can be recycled from blood and reused. Nevertheless, iron deficiency can occur from a number of conditions.

    Inadequate Iron Intake. A healthy diet easily provides enough iron. In general, most people need just 1 mg of extra iron each day. (Menstruating women need 2 mg each day.) This means that lack of iron in the diet is not a common cause of iron deficiency anemia, except in infants. In fact, most American adults may be consuming too much iron in their diet. Iron-poor diets are a cause of anemia only in people with existing risks for iron deficiency. Children who have not yet eaten iron-fortified formulas or iron-enriched cereal may also become anemic.

    Blood Loss. Iron deficiencies most commonly occur from internal blood loss due to other conditions that vary in severity. These conditions include:

    Very heavy periods (menorrhagia), the most common causes of anemia in menstruating women

    Peptic ulcers, which may be caused by H. pylori infections, or use of nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, and naproxen.

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Category: Forex

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