Iron deficiency anemia is a common type of anemia, affecting millions of people worldwide.
Presentation
Iron deficiency anemia is often asymptomatic. Signs and symptoms are non-specific, unless the anemia is severe. Fatigue is the most common symptom [6]. Patients may complain of [1] [3] [8]:
- Fatigue
- Pallor
- Weakness
- Headache
- Palpitations
- Dizziness
- Dyspnea
- Irritability
- Poor concentration, impaired development
- Hair loss
- Impaired temperature regulation
- Decreased resistance to infection
- Worsened cardiac or pulmonary symptoms [1]
Physical findings [5] [6]:
- Impaired growth and development in children [5] [8]
- Pallor of the mucous membranes
- Spoon-shaped nails with decreased capillary refill
- Angular stomatitis
- Splenomegaly in severe, persistent, anemia
- Decreased physical functioning, and mobility, diminished muscle strength
- Cardiovascular complications
Workup
Iron deficiency anemia is diagnosed by the presence of two or more abnormal indices: serum ferritin, transferrin saturation, erythrocyte protoporphyrin.
Initial laboratory testing should include [3] [6]
- Complete blood count (CBC)
- Red blood cell evaluation: hemoglobin, hematocrit, reticulocyte count
- Red blood cell indices: mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin concentration (MCHC), Red blood cell distribution/width (RDW)
- White blood cell count with cell differential
- Platelet count
- Iron studies
- Serum iron
- Serum ferritin
- Total iron binding capacity (TIBC)
- Transferrin saturation percentage
- Reticulocyte count (immature RBC) count, a measure of erythropoietic activity
- Cell morphology
Additional laboratory testing to identify comorbid conditions [3] [6]:
- Serum cobalamin (B-12) and folate levels
- Hemoglobin electrophoresis
- Serum methylmalonic acid and homocysteine levels
- C-reactive protein (CRP) or IL-6 assays, are nonspecific inflammatory markers
- Liver function tests
- Lead level
- Thyroid stimulating hormone (TSH) test
- Serum creatinine and/or calculated glomerular filtration rate
- Complete metabolic panel and hemoglobin A-1-C
Other procedures to further identify possible cause [3]:
- Fecal occult blood test
- Endoscopy
- Electrocardiogram
- Bone marrow aspiration
Serum ferritin is a glycoprotein that indicates available iron stores. It is the first test to become abnormal as iron deficiency begins to develop. It is the best test to assess the degree of iron deficiency as it is not affected by recent ingestion of iron [3].
Treatment
The treatment of iron deficiency anemia involves a two-step approach; restoring iron stores [10] and treating the underlying etiology. Management of the causative disease process will usually improve hemoglobin levels [7].
Treatment depends on the level of iron deficiency and the severity of the anemia, as well as any underlying conditions.
- Oral ferrous iron salts, ferrous sulfate, is the first recommendation, because it is effective and safe. Recommended dosage is 100–200 mg elemental iron daily [3]. Once hemoglobin is normal iron therapy should continue for 3 months to replenish iron stores [3]. Combined iron and folic acid preparations may also be used [3].
- Oral iron should be taken on an empty stomach [3]. Nausea, constipation, and epigastric discomfort are possible adverse effects and may result in non-compliance in 21% of patients [12]. Preparations with lower iron content, slow-release, or enteric-coated forms may prevent these effects [3]. Intermittent iron administration, weekly or on alternate days, may decrease adverse effects. These appear to be as effective as daily dosing.
- Parenteral iron is effective, but should be reserved for patients who cannot tolerate or absorb oral preparations, or whose anemia does not respond to oral medication [3] [7].
- Transfusions with packed red blood cells should be used only in patients with acute bleeding, severe hypoxia, or coronary insufficiency [10]. Management of anemia in pregnancy may require transfusions to prevent maternal or fetal morbidity and mortality [3] [7].
- Erythropoiesis-stimulating agents may also be effective in the treatment of iron deficiency anemia of chronic disease [5]. However, these drugs are not without adverse effects, particularly thromboembolism [1] [7].
- Dietary interventions are necessary in all patients to supplement other forms of treatment.
- Iron absorption depends on the amount of iron in the diet, its bioavailability and physiological needs of the body [3] [10]. The main sources of dietary iron are red meats, fish and poultry [3]. Iron from meat (heme-iron) is absorbed more readily than other forms of iron. Meat also contains compounds that promotes better iron absorption [4]. But approximately 95% of iron in the diet comes from non-hem iron sources [4].
Other dietary recommendations:
- Vitamin C (ascorbic acid) aids iron absorption from non-hem sources [3]. The quality of the source influences this effect [9].
- Tannins in tea and coffee inhibits the absorption of iron when consumed with the iron source [3].
Treatment of iron deficiency anemia should also include patient education including [3]:
- Dietary information regarding iron intake and absorption.
- Need for iron supplements and ways to avoid adverse effects.
- Benefits of Vitamin C.
- Signs and symptoms of worsening anemia.
Excess iron can be toxic, and can lead to cell death and organ damage. Therefore, iron supplementation needs to be carefully monitored [1].
Prognosis
Iron deficiency anemia is a disorder with a good outcome, but it may be caused by an underlying condition with a poor prognosis.
Etiology
Iron deficiency anemia is defined as a hemoglobin level less than 11g/dL (not associated with hemoglobinopathies) [3] [8] [9].
Iron status can be classified as iron sufficient, iron depleted, or iron deficiency anemia [8].
Iron sufficiency indicates that iron supplies are sufficient to supply normal and atypical body requirements for hematopoiesis [9]. In iron depletion, the total stored iron, serum ferritin concentration, is decreased, but the amount of transport iron remains normal [4] [9]. In iron deficiency anemia both stored iron and transport iron are decreased [3]. Therefore, the amount of iron is insufficient to provide what is needed for normal function. This results in inadequate hemoglobin production [3] [8] [9].
Iron deficiency anemia may also be classified by the underlying cause of the disorder [4] [6] [9] [10]:
- Nutritional deficits
- Blood loss
- Malabsorption
- Metabolic dysfunctio
- Diabete
- Chronic renal disease
- Chronic heart disease
Chronic iron deficiency anemia is a common occurrence in the elderly [5] [6] and in chronic disease. Anemia in diabetes and chronic kidney disease is a result of the kidney‘s inability to produce erythropoietin in response to abnormally low hemoglobin [10].
Epidemiology
The prevalence of iron deficiency anemia is affected by diet and socioeconomic factors. It is seen more frequently in those living in poverty [8]. It varies worldwide from 10% in developed nations to 50% in less developed societies [8].
Prevalence of iron deficiency anemia in the elderly increases with age from 8 % at age 65, 12% at age 75, and 23% at age 85+ [6].
The incidence of iron deficiency anemia is higher in men than in women in all age groups [6].
Studies have reported the prevalence of iron deficiency anemia in elderly African Americans to be 3 times higher than in Caucasians, Hispanics, and Asian Americans [6]. However, normal hemoglobin levels are lower in those of African descent, a factor that is not always taken into account [3].
Iron deficiency anemia occurs in almost one third of patients with congestive heart failure (CHF) and 10% to 20% of patients with coronary heart disease (CHD) [2].
Pathophysiology
Iron is necessary for the production of hemoglobin, myoglobin, and enzymes of cellular metabolism. Iron deficiency results in abnormal hemoglobin synthesis leading to reduced ability of the red blood cells to carry oxygen [5]. Iron is involved in the development of the central nervous system, immune system, endocrine system and cardiovascular system [2] [5].
Iron absorption is regulated to replace body losses. Hepcidin is the key regulator of iron absorption in the intestinal tract and the distribution from body stores [1] [8]. Hepcidin, produced in the liver, responds to iron levels and needs by activating ferroportin [1] [9]. Ferroportin is present on the surface of duodenal mucosal cells and facilitates iron absorption. Decreased levels of ferroportin inhibit the absorption of iron into the plasma [1].
Iron deficiency anemia of chronic disease is the result of reduced glomerular filtration rate, reduced plasma flow, impaired erythropoietin production, and hemodilution [5] [11]. These findings are associated with elevated levels of inflammatory cytokines which indicate an autoimmune inflammatory process [7] [11].
Iron is also important in the production of myoglobin and myelin in the brain [8]. Iron deficiency, therefore, affects neurotransmitter metabolism, interfering with psychomotor, intellectual, and emotional function. These effects are seen particularly in children, but may also be responsible for symptoms in the elderly [8].
Prevention
Ways of preventing and treating iron deficiency anemia include [9]:
- Health education regarding diet and iron needs.
- Fiscal measures to fund prevention and treatment programs.
- Screening programs; early identification and treatment may prevent serious complications [3] [9].
- Fortified foods; infant formula, breads and cereals.
- Iron supplementation in pregnant women, at risk infants, and adults at risk [3].
Summary
Iron deficiency anemia is defined as a decrease in red blood cells (RBCs), hemoglobin, and/or red blood cell volume a result of insufficient iron [1]. Iron deficiency is a major public health concern and the most common nutritional deficiency, affecting more than 2 billion people worldwide [2] [3] [4]. Although it is more prevalent in underdeveloped countries, it is still a problem in developed nations [3] [5]. The World Health Organization defines anemia as a hemoglobin (Hgb) level less than 12-13 g/dL [6]. Approximately 50% of anemia is due to iron deficiency [3].
The causes of iron deficiency anemia include: Nutritional deficits, malabsorption, excessive blood loss, and chronic disease [4] [7]. The cause of anemia is determined by patient history, dietary history, and the indices of iron status [7].
Iron deficiency anemia increases with age and as a result of chronic diseases, such as chronic heart disease, diabetes, and chronic renal disease [7].
The effects and complications of iron deficiency anemia are significant. Iron deficiency may interfere with psychomotor development and cognitive function in children [8]. It may increase maternal and fetal morbidity and mortality. Iron deficiency anemia in the elderly and chronically ill decreases quality of life, independence, and productivity. It has an important economically impact by diminishing the individual’s ability to work and perform physical labor [2].
Patient Information
What is iron deficiency anemia?
Iron deficiency anemia refers to a lower than normal level of hemoglobin (the oxygen carrying part of the blood) as a result of insufficient amounts of iron to produce it.
What are the symptoms of iron deficiency anemia?
Mild to moderate iron deficiency anemia is often asymptomatic. The symptoms of iron deficiency anemia include:
- Fatigue, weakness
- Pallor
- Palpitations, dizziness, dyspnea
- Irritability, poor concentration, impaired development
- Decreased resistance to infection
What causes iron deficiency anemia?
Iron deficiency anemia is caused by a decreased intake or absorption of iron and/or an increased need for or loss of hemoglobin. Chronic diseases, such as diabetes, chronic renal disease, and chronic heart disease, may also contribute to iron deficiency anemia.
Who gets iron deficiency anemia?
Anyone, at any age, may develop iron deficiency anemia. Individuals living in poverty or in developing parts of the world, where malnutrition and poor health conditions abound, are at highest risk.
Also at high risk are:
- Women of child bearing age
- Pregnant women
- Infants and toddlers
- Adolescents
- The elderly
- Individuals with chronic disease
How is iron deficiency anemia diagnosed?
Iron deficiency anemia is diagnosed by simple blood tests and is often found with routine blood screening. It may be suspected by symptoms of fatigue and activity intolerance.
How is iron deficiency anemia treated?
Iron deficiency anemia is treated by increasing the intake and absorption of iron. This may be done by increasing the iron in the diet or by supplementing with iron medications. Treating any other underlying cause is also needed.
What are the complications of iron deficiency anemia?
There are many possible complications of iron deficiency anemia. Iron is essential for the production of hemoglobin and for proper development and functioning of the nervous system.
Iron deficiency anemia may cause:
- Increased maternal/fetal mortality and morbidity.
- Increased problems associated with heart and respiratory disease.
- Alterations in growth and development.
- Decreased quality of life of the elderly and chronically ill.
How can iron deficiency anemia be prevented?
Iron deficiency anemia can be prevented by a balanced diet containing sufficient iron, from meats and non-meat sources, folic acid, and Vitamins C and B-12. It may also be prevented by iron supplementation of those at risk for developing iron deficiency anemia. Complications of iron deficiency anemia may be prevented by early detection and treatment through routine screening.
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