Iron deficiency anemia overview: Difference between revisions
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==Overview== | ==Overview== | ||
'''Iron deficiency anemia''' is | '''Iron deficiency anemia''' is caused by lack of [[iron]] in the bloodstream, and the most common cause of [[microcytic anemia]]. | ||
Iron deficiency anemia occurs in the setting of blood loss, insufficient dietary intake or poor oral absorption of [[iron]] from food. Consequently, hemoglobin, which contains iron, cannot be formed. In the United States, 20% of all women of childbearing age have iron deficiency anemia, compared with only 2% of adult men. The principal cause of iron deficiency anemia in premenopausal women is blood lost during [[menstruation|menses]]. | Iron deficiency anemia occurs in the setting of blood loss, insufficient dietary intake or poor oral absorption of [[iron]] from food. Consequently, hemoglobin, which contains iron, cannot be formed, leading to a decrease in the number of [[red blood cells]] in the bloodstream. Symptoms of iron deficiency anemia including fatigue, weakness, shortness of breath, lightheadedness, and pallor. In severe cases, [[pica]] can develop. In the United States, 20% of all women of childbearing age have iron deficiency anemia, compared with only 2% of adult men. The principal cause of iron deficiency anemia in premenopausal women is blood lost during [[menstruation|menses]]. | ||
Iron deficiency anemia is the final stage of [[iron deficiency (medicine)|iron deficiency]]. When the body has sufficient iron to meet its needs (functional iron), the remainder is stored for later use in the [[bone marrow]], [[liver]], and [[spleen]]. Iron deficiency ranges from iron depletion, which yields little physiological damage, to iron deficiency anemia, which can affect the function of numerous [[organ system]]s. Iron depletion causes the amount of stored iron to be reduced, but has no effect on the functional iron. However, a person with no stored iron has no reserves to use if the body requires more iron. In essence, the amount of iron absorbed by the body is not adequate for growth and development or to replace the amount lost. | Iron deficiency anemia is the final stage of [[iron deficiency (medicine)|iron deficiency]]. When the body has sufficient iron to meet its needs (functional iron), the remainder is stored for later use in the [[bone marrow]], [[liver]], and [[spleen]]. Iron deficiency ranges from iron depletion, which yields little physiological damage, to iron deficiency anemia, which can affect the function of numerous [[organ system]]s. Iron depletion causes the amount of stored iron to be reduced, but has no effect on the functional iron. However, a person with no stored iron has no reserves to use if the body requires more iron. In essence, the amount of iron absorbed by the body is not adequate for growth and development or to replace the amount lost. | ||
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==Classification== | ==Classification== | ||
Iron deficiency anemia is classified into stages with normal body iron content, progressive iron depletion, and absolute vs functional deficiency. | |||
==Pathophysiology== | ==Pathophysiology== | ||
==Causes== | ==Causes== | ||
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==Risk Factors== | ==Risk Factors== | ||
Heavy menstrual periods | |||
Prior gastric bypass surgery | |||
Inflammatory bowel disease | |||
==Screening== | ==Screening== | ||
Screening for iron deficiency anemia is done using a complete blood count, which may reveal anemia with microcytosis. Following this, iron studies, including a total serum iron, transferrin saturation, total iron binding capacity, and ferritin, would be indicated. | |||
==Natural History, Complications, and Prognosis== | ==Natural History, Complications, and Prognosis== | ||
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===Physical Examination=== | ===Physical Examination=== | ||
Pallor of mucous membranes, particularly the conjunctiva, suggests anemia, but this was found to be only 28% sensitive and 87% specific in a large study. Therefore, this sign has a high positive predictive value. Other physical examination findings include [[glossitis]], [[angular cheilitis]], [[koilonychia]], and [[dysphagia]]. Patients may also have [[restless legs syndrome]]. | |||
===Laboratory Findings=== | ===Laboratory Findings=== | ||
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===Imaging Findings=== | ===Imaging Findings=== | ||
There are no imaging studies indicated for the evaluation iron deficiency anemia. However, this condition, when present in a male or post-menopausal female, usually warrants further testing for determining a source of bleeding, such an endoscopy or colonoscopy. | |||
===Other Diagnostic Studies=== | ===Other Diagnostic Studies=== | ||
Revision as of 06:10, 24 May 2018
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
Iron deficiency anemia is caused by lack of iron in the bloodstream, and the most common cause of microcytic anemia.
Iron deficiency anemia occurs in the setting of blood loss, insufficient dietary intake or poor oral absorption of iron from food. Consequently, hemoglobin, which contains iron, cannot be formed, leading to a decrease in the number of red blood cells in the bloodstream. Symptoms of iron deficiency anemia including fatigue, weakness, shortness of breath, lightheadedness, and pallor. In severe cases, pica can develop. In the United States, 20% of all women of childbearing age have iron deficiency anemia, compared with only 2% of adult men. The principal cause of iron deficiency anemia in premenopausal women is blood lost during menses.
Iron deficiency anemia is the final stage of iron deficiency. When the body has sufficient iron to meet its needs (functional iron), the remainder is stored for later use in the bone marrow, liver, and spleen. Iron deficiency ranges from iron depletion, which yields little physiological damage, to iron deficiency anemia, which can affect the function of numerous organ systems. Iron depletion causes the amount of stored iron to be reduced, but has no effect on the functional iron. However, a person with no stored iron has no reserves to use if the body requires more iron. In essence, the amount of iron absorbed by the body is not adequate for growth and development or to replace the amount lost.
Historical Perspective
A disease believed to be iron deficiency anemia is described in about 1500 B.C. in the Egyptian Ebers papyrus. It was termed chlorosis or green sickness in Medieval Europe, and iron salts were used for treatment in France by the mid-17th century. Thomas Sydenham recommended iron salts as treatment for chlorosis, but treatment with iron was controversial until the 20th century, when its mechanism of action was more fully elucidated.
Classification
Iron deficiency anemia is classified into stages with normal body iron content, progressive iron depletion, and absolute vs functional deficiency.
Pathophysiology
Causes
Iron deficiency anemia causes can be broadly divided into physiological causes as that seen during growth and pregnancy and due to pathological process. The pathological process could be further divided based on blood loss and inadequate iron absorption.
Differentiating Iron Deficiency Anemia from other Diseases
Iron deficiency anemia and Thalassemia Minor present with many of the same lab results. It is very important not to treat a patient with Thalassemia with an iron supplement as this can lead to hemochromatosis (accumulation of iron in the liver) A hemoglobin electrophoresis would provide useful evidence in distinguishing these two conditions, along with iron studies.
Epidemiology and Demographics
In the United States, the prevalence and severity of anemia have declined in recent years; hence, the proportion of anemia due to causes other than iron deficiency has increased substantially. As a consequence, the effectiveness of anemia screening for iron deficiency has decreased in the United States [1].
Risk Factors
Heavy menstrual periods Prior gastric bypass surgery Inflammatory bowel disease
Screening
Screening for iron deficiency anemia is done using a complete blood count, which may reveal anemia with microcytosis. Following this, iron studies, including a total serum iron, transferrin saturation, total iron binding capacity, and ferritin, would be indicated.
Natural History, Complications, and Prognosis
Diagnosis
Diagnostic criteria
History and Symptoms
Symptoms of iron deficiency are not unique to iron deficiency (i.e. not pathognomonic). Iron is needed for many enzymes to function normally, so a wide range of symptoms may eventually emerge, either as the secondary result of the anemia, or as other primary results of iron deficiency. Iron deficiency represents a spectrum ranging from iron depletion, which causes no physiological impairments, to iron-deficiency anemia, which affects the functioning of several organ systems.
Physical Examination
Pallor of mucous membranes, particularly the conjunctiva, suggests anemia, but this was found to be only 28% sensitive and 87% specific in a large study. Therefore, this sign has a high positive predictive value. Other physical examination findings include glossitis, angular cheilitis, koilonychia, and dysphagia. Patients may also have restless legs syndrome.
Laboratory Findings
Iron status can be assessed through several laboratory tests. Since, each test assesses a different aspect of iron metabolism, results of one test may not always agree with results of other tests. Hematological tests based on characteristics of red blood cells (i.e., Hb concentration, hematocrit, mean cell volume, and red blood celldistribution width) are generally more available and less expensive than are biochemical tests. Biochemical tests (i.e., erythrocyte protoporphyrin concentration, serum ferritin concentration, and transferrin saturation), however, detect earlier changes in iron status. Except for Total iron binding capacity TIBC, transferrin saturation, and soluble transferrin receptor all other components of iron study are decreased in iron deficiency anemia. The soluble transferrin receptor test is a newer test and is found useful in distinguishing iron deficiency anemia from anemia of chronic disease.
Imaging Findings
There are no imaging studies indicated for the evaluation iron deficiency anemia. However, this condition, when present in a male or post-menopausal female, usually warrants further testing for determining a source of bleeding, such an endoscopy or colonoscopy.
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Prevention
References
- ↑ "Recommendations to Prevent and Control Iron Deficiency in the United States". Retrieved 2012-09-18.