Iron deficiency anemia | Description | Prevention | Causes and symptoms | Treatment
Definition
Anemia is a blood disorder characterized by abnormally low levels of healthy red blood cells (RBCs) or reduced hemoglobin (Hgb), the iron-bearing protein in red blood cells that delivers oxygen to tissues throughout the body. Iron deficiency anemia describes anemia that results from low levels of iron, the mineral present in hemoglobin.
Description
Iron deficiency is the world's most common nutritional deficiency, and because this deficiency often results in anemia, iron deficiency anemia is the
most common form of anemia worldwide. In the United States alone, iron deficiency anemia affects about 250,000 young children and about 3 million women of childbearing age. Irondeficiency anemia is less common in senior adults over age 50, usually occurring in conjunction with gastrointestinal bleeding or malabsorption of iron.
Iron is the main component of hemoglobin, the oxygen-carrying substance in RBCs. Iron is distributed in storage pools within the body, including in body tissue cells and RBCs. Total body ironis about 3.5 g in men and 2.5 g in women, primarily related to differences in body size and the reduced storage pool in women due to menstruation.
Iron is poorly absorbed by the body, making it difficult for most adults to meet daily intake requirements through the diet and causing any blood loss to result in iron deficiency. Irondeficiency anemia usually stems from chronic gastrointestinal blood loss through the stool (occult blood loss), and an accompanying loss of iron. This condition may not produce noticeable symptoms and the ongoing blood loss is discovered during a routine physical examination or treatment for another condition. Deficiencies in iron can also occur when the body is using more iron than can be replaced by food or other sources, depleting iron stores. In some individuals, iron deficiency may be the result of an increased need for iron such as increased iron absorption after stomach or small bowel surgery, or the result of malabsorption of iron.
When iron stores are depleted, not enough iron-bearing hemoglobin is available to carry oxygen to body tissues. In turn, fewer RBCs are produced by the body because not enough iron is available for the production of RBCs in bone marrow (erythropoisis). Red blood cells viewed microscopically appear normal in this early stage of iron deficiency anemia, but the total RBC count is reduced. When the body tries to compensate for the iron deficiency by producing more RBCs, it produces cells that are smaller than normal (microcytic anemia), which reduces blood cell volume (hematocrit). At this stage of development, symptoms of iron deficiency anemia begin to develop. The reduction of all three blood parameters—hemoglobin, red blood cell count, and cell volume results in reduced oxygen-carrying capacity of the blood, reducing the oxygenation of body tissues, a condition called hypoxia. Oxygenated blood is needed to give the body energy and to promote effective performance of muscles and organs such as the heart, lungs, and brain.
Demographics
Iron deficiency anemia occurs in 2% of adult men and up to 20% of adult women. African-American and Hispanic-American women are affected more than Caucasian women, and the greatest percentage are between early teens and 49 years of age due to blood loss from menstruation and pregnancy. In men and women age 65 and older, 6–9% of cases of iron deficiency anemia are caused by gastrointestinal bleeding associated with gastrointestinal cancer .
Causes and symptoms
In senior adults, the first suspected cause of iron deficiency anemia is bleeding somewhere in the body, typically chronic bleeding from the gastrointestinal tract that is associated with stomach ulcers, kidney or bladder tumors, colon polyps, or colon cancer . Certain conditions of the body's vascular system (veins and arteries) may also cause regular blood loss, resulting in iron deficiency. Individuals with inflammatory diseases such as rheumatoid arthritis , and individuals with liver diseases such as cirrhosis may develop iron deficiency that can ultimately lead to anemia. Taking non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin , naproxen sodium , or prescription NSAIDs as treatment for inflammatory disease can sometimes cause gastrointestinal bleeding that leads to iron deficiency anemia.
Individuals who do not properly absorb iron from the diet (malabsorption) may develop iron deficiency anemia; this is the most common cause of iron deficiency in post-menopausal women. Poor iron absorption can also cause iron deficiency anemia in patients who have had stomach surgery or small bowel surgery. In rare cases, genitourinary bleeding results in iron deficiency anemia.
The usual signs of anemia, including iron deficiency anemia, are paleness and weakness or lack of sufficient energy for daily activities. Other symptoms include easy bruising of the skin, dizziness and fainting . Nails and hair can become brittle and break easily. Appetite may be reduced.
Diagnosis
Individuals complaining of weakness and fatigue may be evaluated for iron deficiency anemia. The physician first observes the person's skin color for noticeable pallor (pale coloring) and observes the inside of the eyelid or presses on the nail beds to evaluate blood color. Laboratory tests include a complete blood count to determine the RBC count, hemoglobin and hematocrit; all of which are indicators of possible anemia. The RBCs are also examined for size in a stained differential blood smear; smaller than normal red cells with pale centers are indicative of iron deficiency anemia, also called microcytic anemia. Iron levels are evaluated by serum iron ferritin tests, which confirm iron deficiency. Measurement of an iron-bearing protein in the blood (transferrin) may be done to evaluate cellular iron status.
Individuals older than age 65 whose blood tests confirm iron deficiency anemia must be evaluated for the presence of gastrointestinal bleeding. This is done by first testing for the presence of occult blood in a stool sample. If blood is detected, additional diagnostic procedures are done to locate the source of bleeding. Procedures may include examining the upper intestinal tract with a lighted telescopic device (endoscope) that has a tiny digital camera attached. The tube-like endoscope is passed through the nose or mouth and images can be viewed on a monitor as the procedure is performed. Examination of the lower intestinal tract may require colonoscopy , an endoscopic procedure performed with the same type of telescopic device, this time passed through the anus to examine the walls of the colon and rectum.
Treatment
Replacing lost iron stores is an essential part of treatment for iron deficiency anemia. Correcting any sources of bleeding such as gastrointestinal bleeding or certain types of vascular disorders (e.g., hereditary hemorrhagic telangiectasia) is the first concern and must be addressed while iron therapy is underway. Various iron salts (ferrous sulfate, ferrous fuconate, or ferrous fumarate) can provide sufficient iron supplementation. Absorption is enhanced by giving simultaneous vitamin C (ascorbic acid). Some individuals experience stomach upsets when taking oral iron supplements. Oral iron is considered a safer form of iron than injection, but individuals who do not tolerate oral iron may need iron by injection. Sodium ferric gluconate, is a safe form of injectable iron approved by the FDA in 1999, as is iron sucrose, which was approved in 2000.
QUESTIONS TO ASK YOUR DOCTOR
· Why have I developed iron deficiency anemia?
· How can I increase the iron in my blood?
· Will taking iron supplements be the only treatment I need?
· How soon will I begin to feel stronger?
· How can I avoid becoming anemic again?
The normal response to iron replacement typically occurs 7 to 10 days after the start of therapy when new RBCs (reticulocytes) can be seen in blood smears. Hemoglobin usually returns to normal in about two months, but iron replacement therapy may continue for six months to ensure complete replacement of iron stores. Individuals with illnesses such as infection or cancer may not respond well to iron replacement therapy and may require longer treatment or blood transfusion. Only rarely are blood transfusions needed to replace lost blood and iron, usually in patients who do not respond to other forms of iron therapy or whose bleeding is not controlled.
Nutrition/Dietetic concerns
Consumption of meat that contains haem iron (found in animal meats) is easily absorbed. Vitamin C (ascorbic acid) maintains an acidic environment in the stomach and is known to help the absorption of iron from non-meat sources the diet (such as bread, fruit, cereal, etc.) and is especially helpful when taking iron supplements to correct iron deficiency anemia. Coffee, tea, and alcoholic beverages, especially wine, interfere with absorption of iron and should be avoided while taking replacement iron. Antacids may also interfere with iron absorption by changing the acid environment of the stomach to alkaline; antacid intake should be avoided while using iron supplements. To maintain iron stores, all adults should consume a diet high in iron, including red meat, fish, eggs, beans and green leafy vegetables.
KEY TERMS
Erythropoisis —The production of red blood cells in the body.
Hematocrit —An indication of blood volume determined by the percentage of blood composed of red blood cells and hemoglobin compared to the liquid portion called plasma.
Hypoxia —Decreased levels of oxygen in the blood, blood gases, and tissues of body organs.
Malabsorption —Decreased ability to absorb nutrients through the body's normal absorption processes.
Microcytic anemia —Any type of anemia in which red blood cells are of smaller than normal size.
Reticulocytes —Young red blood cells formed in bone marrow that make up about 1% of all red blood cells circulating in the veins and arteries.
Prognosis
Iron deficiency anemia can be corrected in most individuals regardless of cause. In individuals with gastrointestinal bleeding, the underlying source of bleeding must be successfully treated to obtain a good result with iron supplementation and a return to good health. Malabsorption is more difficult to treat but iron levels can usually be restored and the individual typically resumes good health in the absence of other underlying disease. Untreated iron deficiency anemia can lead to serious problems such as heart beat irregularities (cardiac arrhythmias ) and angina , which is heart paincaused by decreased oxygen being delivered to the heart through the blood.
Prevention
Prevention of iron deficiency anemia in senior adults depends on sufficient iron intake and prevention of gastrointestinal bleeding. Iron can be obtained in the diet by consuming a variety of meats and vegetables. Foods high in iron include eggs, red meat, liver, fish, beans, green leafy vegetables, almonds, avocados, blackstrap molasses, brewer's yeast, dried plums (prunes), dates, raisins, and seaweeds such as dulse, hijiki and kelp. Iron supplements such as ferrous sulfate can be taken if recommended by the physician; iron supplements should be taken with vitamin C and absorption can be increased by consuming meat regularly.
Caregiver concerns
Individuals with iron deficiency anemia typically feel weak and fatigued. For safety reasons and to prevent falling, they should be observed for signs of weakness or dizziness such as lack of stability when walking. A healthy diet should be maintained, including a range of meats, eggs, fish, beans and vegetables. Coffee, tea and alcohol, especially wine, should be avoided because they interfere withiron absorption. Any excessive bruising should be reported to the physician.
Resources
BOOKS
“Anemias Caused by Deficient Erythropoiesis.” The Merck Manual of Diagnosis and Therapy, Section 11. Edited by R. S. Porter. White House Station, NJ: Merck Research Laboratories, 2007.
PERIODICALS
Killip, S., J. M. Bennett, and M. D. Chambers. “Iron Deficiency Anemia.” American Family Physician75, no. 5 (2007).
OTHER
“Iron Deficiency Anemia.” Food & Nutrition Mayo Foundation for Medical Education and Research. March 7, 2007 [cited April 12, 2008].http://www.mayoclinic.com/health/iron-deficiency-anemia/DS00323.
ORGANIZATIONS
American Academy of Family Physicians, 114 Tomahawk Creek Parkway, Leawood, KS, 66211-2672, (800) 274-2237, (913) 906-6269, fp@aafp.org, http://www.familydoctor.org.
American Dietetic Association, 120 South Riverside Plaza, Chicago, IL, 60606-6995, (800) 366-1655,http://www.eatright.org.
National Heart, Lung, and Blood Institute (NHLBI), 6701 Rockledge Drive, P.O. Box 30105, Bethesda, MD, 20824-0105, (301) 592-8573, http://www.nhlbi.nih.gov.
L. Lee Culvert
