Iron deficiency anemia overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Jogeet Singh Sekhon, M.D. [2]
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. 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
Iron deficiency anemia was discovered in 1852 by Karl Vierordt and his student H. Welcher.
Classification
There is no established system for the classification of iron deficiency anemia. However, based on the pahology it can be divided into 2 types on the basis of cause of iron deficiency into absolute iron deficiency and functional iron deficiency.
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Pathophysiology
Iron is needed for haemoglobin synthesis which is essential for oxygen transport in the body. Iron is stored as ferritin in the body and transported as transferrin. The source of iron is diet and recycling iron from reticuloendothelial cells. The absorption of iron is highly regulated by hepcidin. Loss of iron from the body, inadequate intake or increased hepcidin can lead to iron deficiency anemia
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
Iron deficiency anemia can occur in any age group, region, gender but there are some factors that predispose individuals of some groups to develop iron deficiency.
Risk Factors
Risk of iron deficiency anemia is more in those individuals who consume less iron in diet and who are at increased risk of bleeding.
Screening
Screening is recommended in pregnant women and new borns.
Natural History, Complications, and Prognosis
The symptoms of iron deficiency are similar as in any other case of anemia. Iron deficiency anemia has age specific presentations. Iron deficiency anemia can lead to severe complications if not treated. The prognosis of iron deficiency anemia is good if iron supplementation is started.
Diagnosis
Diagnostic criteria
Iron deficiency anemia is diagnosed on the baisis of results of CBC, peripheral blood film and iron studies.
History and Symptoms
Iron deficiency anemia may be asymptomatic, or present with very few symptoms or very severe weakness depending on the severity of anemia.
Physical Examination
Patients with iron deficiency anemia may appear normal in some cases but usually if anemia is moderate or severe, the patient would appear pale. All organ systems can be involved by the effects of anemia.
Laboratory Findings
Iron studies are conducted if microcytic hypochromic anemia is found on complete blood count and peripheral blood film. Iron studies are helpful in making the diagnosis of iron deficiency anemia, with serum ferritin levels being the most widely used test.
Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Treatment of iron deficiency anemia includes iron supplementation and treating the cause of the iron deficiency. Treatment is given according to the severity of anemia
Surgery
Prevention
Maintaining adequate iron stores in the body, is the most effective approach to prevent iron deficiency anemia. The source of iron to the body is diet. Consuming iron rich food will prevent iron deficiency anemia.