Iron-deficiency anemia
Template:Short description Template:Use dmy dates Template:Cs1 config Template:Infobox medical condition (new) Iron-deficiency anemia is anemia caused by a lack of iron.<ref name="NIH2014Def">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Anemia is defined as a decrease in the number of red blood cells or the amount of hemoglobin in the blood.<ref name="NIH2014Def" /> When onset is slow, symptoms are often vague such as feeling tired, weak, short of breath, or having decreased ability to exercise.<ref name="EBM2013" /> Anemia that comes on quickly often has more severe symptoms, including confusion, feeling like one is going to pass out or increased thirst.<ref name="EBM2013" /> Anemia is typically significant before a person becomes noticeably pale.<ref name="EBM2013" /> Children with iron deficiency anemia may have problems with growth and development.<ref name="NIH2014Def" /> There may be additional symptoms depending on the underlying cause.<ref name="EBM2013">Template:Cite journal</ref>
Iron-deficiency anemia is caused by blood loss, insufficient dietary intake, or poor absorption of iron from food.<ref name="NIH2014Def" /> Sources of blood loss can include heavy periods, childbirth, uterine fibroids, stomach ulcers, colon cancer, and urinary tract bleeding.<ref name="NIH2014Ca" /> Poor absorption of iron from food may occur as a result of an intestinal disorder such as inflammatory bowel disease or celiac disease, or surgery such as a gastric bypass.<ref name="NIH2014Ca">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In the developing world, parasitic worms, malaria, and HIV/AIDS increase the risk of iron deficiency anemia.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Diagnosis is confirmed by blood tests.<ref name="NIH2014Diag">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Iron deficiency anemia can be prevented by eating a diet containing sufficient amounts of iron or by iron supplementation.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Foods high in iron include meat, nuts, and foods made with iron-fortified flour.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Treatment may include dietary changes, iron supplements, and dealing with underlying causes, for example medical treatment for parasites or surgery for ulcers.<ref name="NIH2014Def" /> Supplementation with vitamin C may be recommended due to its potential to aid iron absorption.<ref name="NIH2014Tx">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Severe cases may be treated with blood transfusions or iron infusions.<ref name="NIH2014Def" />
Iron-deficiency anemia affected about 1.48 billion people in 2015.<ref name="GBD2015Pre">Template:Cite journal</ref> A lack of dietary iron is estimated to cause approximately half of all anemia cases globally.<ref>Template:Cite book</ref> Women and young children are most commonly affected.<ref name="NIH2014Def" /> In 2015, anemia due to iron deficiency resulted in about 54,000 deaths – down from 213,000 deaths in 1990.<ref name="GBD2015De">Template:Cite journal</ref><ref>Template:Cite journal</ref> Template:TOC limit
Signs and symptomsEdit
Iron-deficiency anemia may be present without a person experiencing symptoms.<ref name=":10">Template:Cite book</ref> It tends to develop slowly; therefore the body has time to adapt, and the disease often goes unrecognized for some time.<ref name=":5" /> If symptoms present, patients may present with the sign of pallor (reduced oxyhemoglobin in skin or mucous membranes),<ref name=":14">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and the symptoms of feeling tired, weak, dizziness, lightheadedness, poor physical exertion, headaches, decreased ability to concentrate, cold hands and feet, cold sensitivity, increased thirst and confusion.<ref name=":10" /><ref name=":14" /> None of these symptoms (or any of the others below) are sensitive or specific.
In severe cases, shortness of breath can occur.<ref name=":9">Template:Cite book</ref> Pica may also develop; of which consumption of ice, known as pagophagia, has been suggested to be the most specific for iron deficiency anemia.<ref name=":5"/>
Other possible symptoms and signs of iron-deficiency anemia include:<ref name="NIH2014Def" /><ref name=":5"/><ref name=":9"/><ref name=":4"/>
Child developmentEdit
Iron-deficiency anemia is associated with poor neurological development, including decreased learning ability and altered motor functions.<ref>Template:Cite book</ref><ref name=":6">Template:Cite book</ref> This is because iron deficiency impacts the development of the cells of the brain called neurons. When the body is low on iron, the red blood cells get priority on iron, and it is shifted away from the neurons of the brain. Exact causation has not been established, but there is a possible long-term impact from these neurological issues.<ref name=":6"/>
CauseEdit
A diagnosis of iron-deficiency anemia requires further investigation into its cause.<ref name=":3"/> It can be caused by increased iron demand, increased iron loss, or decreased iron intake.<ref name="npsnews">Template:Cite journal</ref> Increased iron demand often occurs during periods of growth, such as in children and pregnant women.<ref name=":13">Template:Cite book</ref> For example, during stages of rapid growth, babies and adolescents may outpace their dietary intake of iron which can result in deficiency in the absence of disease or a grossly abnormal diet.<ref name="npsnews" /> Iron loss is typically from blood loss.<ref name=":13" /> One example of blood loss is by chronic gastrointestinal blood loss, which could be linked to a possible cancer.<ref name=":3"/> In women of childbearing age, heavy menstrual periods can be a source of blood loss causing iron-deficiency anemia.<ref name=":3"/> People who do not consume much iron in their diet, such as vegans or vegetarians, are also at increased risk of developing iron deficiency anemia.<ref name=":10"/>
Parasitic diseaseEdit
The leading cause of iron-deficiency anemia worldwide is a parasitic disease known as a helminthiasis caused by infestation with parasitic worms (helminths); specifically, hookworms. The hookworms most commonly responsible for causing iron-deficiency anemia include Ancylostoma duodenale, Ancylostoma ceylanicum, and Necator americanus.<ref name=":3">Template:Cite book</ref><ref name=":8">Template:Cite book</ref> The World Health Organization estimates that approximately two billion people are infected with soil-transmitted helminths worldwide.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }} World Health Organization Fact Sheet No. 366, Soil-Transmitted Helminth Infections, updated June 2013</ref> Parasitic worms cause both inflammation and chronic blood loss by binding to a human's small-intestinal mucosa, and through their means of feeding and degradation, they can ultimately cause iron-deficiency anemia.<ref name=":5"/><ref name=":8"/>
Blood lossEdit
Red blood cells contain iron, so blood loss also leads to iron loss. There are several causes of blood loss, including menstrual bleeding, gastrointestinal bleeding, stomach ulcers, and bleeding disorders.<ref name="Ganz_2016">Template:Cite book</ref> The bleeding may occur quickly or slowly. Slow, chronic blood loss within the body – such as from a peptic ulcer, angiodysplasia, inflammatory bowel disease, a colon polyp or gastrointestinal cancer (e.g., colon cancer) – can cause iron-deficiency anemia.<ref name="Rockey">Template:Cite journal</ref>
Menstrual bleedingEdit
Menstrual bleeding is a common cause of iron deficiency anemia in women of childbearing age.<ref name="Ganz_2016" /> Women with menorrhagia (heavy menstrual periods) are at risk of iron deficiency anemia because they are at higher than normal risk of losing more iron during menstruation than is replaced in their diet. Most women lose about 40 mL of blood per cycle. Some birth control methods, such as pills and IUDs, may decrease the amount of blood and therefore iron lost during a menstrual cycle.<ref name="Ganz_2016" /> Intermittent iron supplementation may be as effective a treatment in these cases as daily supplements and reduce some of the adverse effects of long-term daily supplements.<ref>Template:Cite journal</ref>
Gastrointestinal bleedingEdit
The most common cause of iron deficiency anemia in men and post-menopausal women is gastrointestinal bleeding.<ref name="Ganz_2016" /> There are many sources of gastrointestinal tract bleeding, including the stomach, esophagus, small intestine, and the large intestine (colon). Gastrointestinal bleeding can result from regular use of some medications, such as non-steroidal anti-inflammatory drugs (e.g. aspirin), as well as antiplatelets such as clopidogrel and anticoagulants such as warfarin; however, these are required in some patients, especially those with states causing a tendency to form blood clots. Colon cancer, which typically occurs in older individuals, is another potential cause of gastrointestinal bleeding.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In addition, some bleeding disorders, such as von Willebrand disease and polycythemia vera, can cause gastrointestinal bleeding.<ref name="Ganz_2016" />
Blood donationEdit
Frequent blood donors are also at risk for developing iron deficiency anemia.<ref>Template:Cite book</ref> When whole blood is donated, approximately 200 mg of iron is lost from the body.<ref name="Ganz_2016" /> The blood bank screens people for anemia before drawing blood for donation. If the patient has anemia, blood is not drawn.<ref name="Ganz_2016" /> Less iron is lost if the person is donating platelets or white blood cells.<ref name="Ganz_2016" />
DietEdit
The body normally gets the iron it requires from food. If a person consumes too little iron, or iron that is poorly absorbed (non-heme iron), they can become iron deficient over time. Examples of iron-rich foods include meat, eggs, leafy green vegetables and iron-fortified foods. For proper growth and development, infants and children need dietary iron.<ref name="MayoClinic">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> For children, a high intake of cow's milk is associated with an increased risk of iron-deficiency anemia.<ref name="Dec2014" /> Other risk factors include low meat intake and low intake of iron-fortified products.<ref name="Dec2014">Template:Cite journal</ref>
The National Academy of Medicine updated Estimated Average Requirements (EAR) and Recommended Dietary Allowances (RDA) in 2001. The current EAR for iron for women ages 14–18 is 7.9 mg/day, 8.1 for ages 19–50, and 5.0 thereafter (post menopause). For men the EAR is 6.0 mg/day for ages 19 and up. The RDA is 15.0 mg/day for women ages 15–18, 18.0 for 19–50, and 8.0 thereafter; for men, 8.0 mg/day for ages 19 and up. (Recommended Dietary Allowances are higher than Estimated Average Requirements so as to cover people with higher than average requirements.) The RDA for pregnancy is 27 mg/day, and during lactation, 9 mg/day. For children ages 1–3 years it is 7 mg/day, 10 for ages 4–8 and 8 for ages 9–13.<ref>Template:Cite book</ref> The European Food Safety Authority refers to the collective set of information as Dietary Reference Values, with Population Reference Intakes instead of RDAs, and Average Requirements instead of EARs. For women the Population Reference Intake is 13 mg/day ages 15–17 years, 16 mg/day for women ages 18 and up who are premenopausal, and 11 mg/day postmenopausal; for pregnancy and lactation, 16 mg/day. For men the Population Reference Intake is 11 mg/day ages 15 and older. For children ages 1 to 14 the Population Reference Intake increases from 7 to 11 mg/day. The Population Reference Intakes are higher than the US RDAs, with the exception of pregnancy.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Iron malabsorptionEdit
Iron from food is absorbed into the bloodstream in the small intestine, primarily in the duodenum.<ref>Template:Cite book</ref> Iron malabsorption is a less common cause of iron-deficiency anemia, but many gastrointestinal disorders can reduce the body's ability to absorb iron.<ref name=":0">Template:Cite bookTemplate:Dead link</ref> There are different mechanisms that may be present.
In coeliac disease, abnormal changes in the structure of the duodenum can decrease iron absorption.<ref name=":1">Template:Cite book</ref> Abnormalities or surgical removal of the stomach can also lead to malabsorption by altering the acidic environment needed for iron to be converted into its absorbable form.<ref name=":0"/> If there is insufficient production of hydrochloric acid in the stomach, hypochlorhydria/achlorhydria can occur (often due to chronic H. pylori infections or long-term proton-pump inhibitor therapy), inhibiting the conversion of ferric iron to the absorbable ferrous iron.<ref name=":1"/>
Bariatric surgery is associated with an increased risk of iron deficiency anemia due to malabsorption of iron.<ref name="Camaschella" /> During a Roux-en-Y anastamosis, which is commonly performed for weight management and diabetes control, the stomach is made into a small pouch and this is connected directly to the small intestines further downstream (bypassing the duodenum as a site of digestion). About 17–45% of people develop iron deficiency after a Roux-en-Y gastric bypass.<ref>Template:Cite journal</ref>
Pregnant womenEdit
Without iron supplementation, iron-deficiency anemia occurs in many pregnant women because their iron stores need to serve their own increased blood volume and be a source of hemoglobin for the growing baby and placental development.<ref name="MayoClinic" /> Other less common causes are intravascular hemolysis and hemoglobinuria. Iron deficiency in pregnancy appears to cause long-term and irreversible cognitive problems in the baby.<ref>Template:Cite journal</ref>
Iron deficiency affects maternal well-being by increasing risks for infections and complications during pregnancy.<ref name=":16" /> Some of these complications include pre-eclampsia, bleeding problems, and perinatal infections.<ref name=":16" /> Iron deficiency can lead to improper development of fetal tissues.<ref>Template:Cite journal</ref> Oral iron supplementation during the early stages of pregnancy, specifically the first trimester, is suggested to decrease the adverse effects of iron-deficiency anemia throughout pregnancy and to decrease the negative impact that iron deficiency has on fetal growth.<ref name=":16" /> Iron supplements may lead to a risk for gestational diabetes, so pregnant women with adequate hemoglobin levels are recommended not to take iron supplements.<ref>Template:Cite journal</ref> Iron deficiency can lead to premature labor and to problems with neural functioning, including delays in language and motor development in the infant.<ref name=":16" />
Some studies show that women pregnant during their teenage years can be at greater risk of iron-deficiency anemia due to an already increased need for iron and other nutrients during adolescent growth spurts.<ref name=":16" />
ChildrenEdit
Babies are at increased risk of developing iron deficiency anemia due to their rapid growth.<ref name=":13" /> Their need for iron is greater than they are getting in their diet.<ref name=":13" /> Babies are born with iron stores; however, these iron stores typically run out by 4–6 months of age. In addition, infants who are given cow's milk too early can develop anemia due to gastrointestinal blood loss.<ref name=":13" />
Children who are at risk for iron-deficiency anemia include:<ref>Template:Cite book</ref>
- Preterm infants
- Low birth weight infants
- Infants fed with cow's milk under 12 months of age
- Breastfed infants who have not received iron supplementation after age 6 months, or those receiving non-iron-fortified formulas
- Children between the ages of 1 and 5 years old who receive more than 24 ounces (700 mL) of cow milk per day
- Children with low socioeconomic status
- Children with special health care needs
- Children of Hispanic ethnicity<ref name=":11" />
- Children who are overweight<ref name=":11" />
HepcidinEdit
Decreased levels of serum and urine hepcidin are early indicators of iron deficiency.<ref>Template:Cite journal</ref> Hepcidin concentrations are also connected to the complex relationship between malaria and iron deficiency.<ref>Template:Cite journal</ref>
MechanismEdit
Anemia can result from significant iron deficiency.<ref name=":0"/> When the body has sufficient iron to meet its needs (functional iron), the remainder is stored for later use in cells, mostly in the bone marrow and liver.<ref name=":0"/> These stores are called ferritin complexes and are part of the human (and other animals) iron metabolism systems. Men store about 3.5 g of iron in their body, and women store about 2.5 g.<ref name=":10"/>
Hepcidin is a peptide hormone produced in the liver that is responsible for regulating iron levels in the body. Hepcidin decreases the amount of iron available for erythropoesis (red blood cell production).<ref name="Camaschella" /> Hepcidin binds to and induces the degradation of ferroportin, which is responsible for exporting iron from cells and mobilizing it to the bloodstream.<ref name="Camaschella">Template:Cite journal</ref> Conditions such as high levels of erythropoesis, iron deficiency and tissue hypoxia inhibit hepcidin expression.<ref name="Camaschella" /> Whereas systemic infection or inflammation (especially involving the cytokine IL-6) or increased circulating iron levels stimulate hepcidin expression.<ref name="Camaschella" />
Iron is a mineral that is important in the formation of red blood cells in the body, particularly as a critical component of hemoglobin.<ref name=":3"/> About 70% of the iron found in the body is bound to hemoglobin.<ref name=":10"/> Iron is primarily absorbed in the small intestine, in particular the duodenum and jejunum. Certain factors increase or decrease absorption of iron. For example, taking Vitamin C with a source of iron is known to increase absorption. Some medications such as tetracyclines and antacids can decrease absorption of iron.<ref name=":10"/> After being absorbed in the small intestine, iron travels through blood, bound to transferrin, and eventually ends up in the bone marrow, where it is involved in red blood cell formation.<ref name=":3"/> When red blood cells are degraded, the iron is recycled by the body and stored.<ref name=":3"/>
When the amount of iron needed by the body exceeds the amount of iron that is readily available, the body can use iron stores (ferritin) for a period of time, and red blood cell formation continues normally.<ref name=":0"/> However, as these stores continue to be used, iron is eventually depleted to the point that red blood cell formation is abnormal.<ref name=":0"/> Ultimately, anemia ensues, which by definition is a hemoglobin lab value below normal limits.<ref name="NIH2014Def" /><ref name=":0"/>
DiagnosisEdit
Conventionally, a definitive diagnosis requires a demonstration of depleted body iron stores obtained by bone marrow aspiration, with the marrow stained for iron.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> However, with the availability of reliable blood tests that can be more readily collected for iron-deficiency anemia diagnosis, a bone marrow aspiration is usually not obtained.<ref name=":7"/> Furthermore, a study published in April 2009 questions the value of stainable bone marrow iron following parenteral iron therapy.<ref>Template:Cite journal</ref> Once iron deficiency anemia is confirmed, gastrointestinal blood loss is presumed to be the cause until proven otherwise since it can be caused by an otherwise asymptomatic colon cancer. The initial evaluation must include esophagogastroduodenoscopy and colonoscopy to evaluate for cancer or bleeding of the gastrointestinal tract.<ref name="Rockey"/>
A thorough medical history is important to the diagnosis of iron-deficiency anemia. The history can help to differentiate common causes of the condition such as menstruation in women or blood in the stool.<ref>Template:Cite journal</ref> A travel history to areas in which hookworms and whipworms are endemic may also help guide certain stool tests for parasites or their eggs.<ref>Template:Cite book</ref> Although symptoms can play a role in identifying iron-deficiency anemia, they are often vague, which may limit their contribution to determining the diagnosis.Template:Citation needed
Blood testsEdit
| Change | Parameter |
|---|---|
| ↓ | ferritin, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin |
| ↑ | total iron-binding capacity, transferrin, red blood cell distribution width |
Anemia is often discovered by routine blood tests. A sufficiently low hemoglobin by definition makes the diagnosis of anemia, and a low hematocrit value is also characteristic of anemia. Further studies will be undertaken to determine the anemia's cause. If the anemia is due to iron deficiency, one of the first abnormal values to be noted on a complete blood count, as the body's iron stores begin to be depleted, will be a high red blood cell distribution width, reflecting an increased variability in the size of red blood cells.<ref name=":5">Template:Cite book</ref><ref name=":3"/>
A low mean corpuscular volume also appears during the course of body iron depletion. It indicates a high number of abnormally small red blood cells. A low mean corpuscular volume, a low mean corpuscular hemoglobin or mean corpuscular hemoglobin concentration, and the corresponding appearance of red blood cells on visual examination of a peripheral blood smear narrows the problem to a microcytic anemia (literally, a small red blood cell anemia).<ref name=":5"/>
The blood smear of a person with iron-deficiency anemia shows many hypochromic (pale, relatively colorless) and small red blood cells, and may also show poikilocytosis (variation in shape) and anisocytosis (variation in size).<ref name=":5"/><ref name=":7">Template:Cite book</ref> With more severe iron-deficiency anemia, the peripheral blood smear may show hypochromic, pencil-shaped cells and, occasionally, small numbers of nucleated red blood cells.<ref>Template:Cite book</ref> The platelet count may be slightly above the high limit of normal in iron-deficiency anemia (termed a mild thrombocytosis), but severe cases can present with thrombocytopenia (low platelet count).<ref>Template:Cite book</ref>
Iron-deficiency anemia is confirmed by tests that include serum ferritin, serum iron level, serum transferrin, and total iron binding capacity.<ref>Template:Cite journal</ref> A low serum ferritin is most commonly found. However, serum ferritin can be elevated by any type of chronic inflammation and thus is not consistently decreased in iron-deficiency anemia.<ref name=":3" /> Serum iron levels may be measured, but serum iron concentration is not as reliable as the measurement of both serum iron and serum iron-binding protein levels.<ref name=":4">Template:Cite book</ref> The percentage of iron saturation (or transferrin saturation index or percent) can be measured by dividing the level of serum iron by total iron binding capacity and is a value that can help to confirm the diagnosis of iron-deficiency anemia; however, other conditions must also be considered, including other types of anemia.<ref name=":4"/>
Another finding that can be used is the level of red blood cell distribution width.<ref>Template:Cite book</ref> During haemoglobin synthesis, trace amounts of zinc will be incorporated into protoporphyrin in the place of iron which is lacking. Protoporphyrin can be separated from its zinc moiety and measured as free erythrocyte protoporphyrin, providing an indirect measurement of the zinc-protoporphyrin complex. The level of free erythrocyte protoporphyrin is expressed in either μg/dl of whole blood or μg/dl of red blood cells. An iron insufficiency in the bone marrow can be detected very early by a rise in free erythrocyte protoporphyrin.Template:Citation needed
Further testing may be necessary to differentiate iron-deficiency anemia from other disorders, such as thalassemia minor.<ref>Template:Cite book</ref> It is very important not to treat people with thalassemia with an iron supplement, as this can lead to hemochromatosis. A hemoglobin electrophoresis provides useful evidence for distinguishing these two conditions, along with iron studies.<ref name=":4"/><ref>Template:Cite book</ref>
ScreeningEdit
It is unclear if screening pregnant women for iron-deficiency anemia during pregnancy improves outcomes in the United States.<ref>Template:Cite journal</ref> The same holds true for screening children who are 6 to 24 months old.<ref>Template:Cite journal</ref> Even so, screening is a Level B recommendation suggested by the US Preventative Services Task Force in pregnant women without symptoms and in infants considered high risk. Screening is done with either a hemoglobin or hematocrit lab test.<ref name=":11"/>
TreatmentEdit
Treatment should take into account the cause and severity of the condition.<ref name="NIH2014Tx" /> If the iron-deficiency anemia is a result of blood loss or another underlying cause, treatment is geared toward addressing the underlying cause.<ref name="NIH2014Tx" /> Most cases of iron deficiency anemia are treated with oral iron supplements.<ref name=":12">Adamson JW (2014). Iron Deficiency and Other Hypoproliferative Anemias. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 19e New York, NY: McGraw-Hill.</ref> In severe acute cases, treatment measures are taken for immediate management in the interim, such as blood transfusions or intravenous iron.<ref name="NIH2014Tx" />
For less severe cases, treatment of iron-deficiency anemia includes dietary changes to incorporate iron-rich foods into regular oral intake and oral iron supplementation.<ref name="NIH2014Tx" /> Foods rich in ascorbic acid (vitamin C) can also be beneficial, since ascorbic acid enhances iron absorption.<ref name="NIH2014Tx" /> Oral iron supplements are available in multiple forms. Some are in the form of pills and some are drops for children.<ref name="NIH2014Tx" />
Most forms of oral iron replacement therapy are absorbed well by the small intestine; however, there are certain preparations of iron supplements that are designed for longer release in the small intestine than other preparations.<ref name=":12" /> Oral iron supplements are best taken up by the body on an empty stomach because food can decrease the amount of iron absorbed from the small intestine.<ref name=":12" /> The dosing of oral iron replacement therapy is as much as 100–200 mg per day in adults and 3–6 mg per kilogram in children.<ref name="Camaschella" /> This is generally spread out as 3–4 pills taken throughout the day.<ref name=":12" />
The various forms of treatment are not without possible adverse side effects. Iron supplementation by mouth commonly causes negative gastrointestinal effects, including constipation, nausea, vomiting, metallic taste to the oral iron and dark colored stools.<ref name=":2" /><ref name="Camaschella" /> Constipation is reported by 15–20% of patients taking oral iron therapy.<ref name=":12" /> Preparations of iron therapy that take longer to be absorbed by the small intestine (extended release iron therapy) are less likely to cause constipation.<ref name=":12" />
It can take six months to one year to get blood levels of iron up to a normal range and provide the body with iron stores.<ref name=":12" /> Oral iron replacement may not be effective in cases of iron deficiency due to malabsorption, such as celiac disease, inflammatory bowel disease, or H. pylori infection; these cases would require treatment of the underlying disease to increase oral absorption or intravenous iron replacement.<ref name="Camaschella" />
As iron-deficiency anemia becomes more severe, if the anemia does not respond to oral treatments, or if the treated person does not tolerate oral iron supplementation, then other measures may become necessary.<ref name="NIH2014Tx" /><ref name=":2">Template:Cite book</ref> Two options are intravenous iron injections and blood transfusion.<ref name=":12"/> Intravenous can be for people who do not tolerate oral iron, who are unlikely to respond to oral iron, or who require iron on a long-term basis.<ref name=":12"/> For example, people receiving dialysis treatment who are also getting erythropoietin or another erythropoiesis-stimulating agent are given parenteral iron, which helps the body respond to the erythropoietin agents to produce red blood cells.<ref name=":2"/><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="Camaschella" />
Intravenous iron can induce an allergic response that can be as serious as anaphylaxis, although different formulations have decreased the likelihood of this adverse effect.<ref name=":2"/> In certain cases intravenous iron is both safer and more effective than the oral route.<ref>Template:Cite journal</ref> For patients with severe anemia such as from blood loss, or who have severe symptoms such as cardiovascular instability, a blood transfusion may be considered.<ref name=":12"/>
Low-certainty evidence suggests that IBD-related anemia treatment with Intravenous (IV) iron infusion may be more effective than oral iron therapy, with fewer people needing to stop treatment early due to adverse effects.<ref name=":02">Template:Cite journal</ref> The type of iron preparation may be an important determinant of clinical benefit. Moderate-certainty evidence suggests response to treatment may be higher when IV ferric carboxymaltose, rather than IV iron sucrose preparation is used, despite very-low certainty evidence of increased adverse effects, including bleeding, in those receiving ferric carboxymaltose treatment.<ref name=":02" />
Ferric maltol, marketed as Accrufer and Ferracru, is available in oral and IV preparations. When used as a treatment for IBD-related anemia, very low certainty evidence suggests a marked benefit with oral ferric maltol compared with placebo. However it was unclear whether the IV preparation was more effective than oral ferric maltol.<ref name=":03">Template:Cite journal</ref>
A Cochrane review of controlled trials comparing intravenous (IV) iron therapy with oral iron supplements in people with chronic kidney disease, found low-certainty evidence that people receiving IV-iron treatment were 1.71 times as likely to reach their target hemoglobin levels.<ref name=":15">Template:Cite journal</ref> Overall, hemoglobin was 0.71g/dl higher than those treated with oral iron supplements. Iron stores in the liver, estimated by serum ferritin, were also 224.84 μg/L higher in those receiving IV-iron.<ref name=":15" /> However there was also low-certainty evidence that allergic reactions were more likely following IV-iron therapy. It was unclear whether type of iron therapy administration affects the risk of death from any cause, including cardiovascular, nor whether it may alter the number of people who may require a blood transfusion or dialysis.<ref name=":15" />
Ferric derisomaltose (Monoferric) was approved in the United States in January 2020, for the treatment of iron deficiency anemia.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="Monoferric FDA label">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
EpidemiologyEdit
A moderate degree of iron-deficiency anemia affects approximately 610 million people worldwide or 8.8% of the population.<ref name="LancetEpi2012">Template:Cite journal</ref> It is slightly more common in females (9.9%) than males (7.8%).<ref name="LancetEpi2012" /> Up to 15% of children ages 1–3 years have iron deficiency anemia.<ref name=":11">Primack BA, Mahaniah KJ. Anemia. In: South-Paul JE, Matheny SC, Lewis EL. eds. CURRENT Diagnosis & Treatment: Family Medicine, 4e New York, NY: McGraw-Hill; . Accessed November 30, 2018.</ref> Mild iron deficiency anemia affects another 375 million.<ref name="LancetEpi2012" /> Iron deficiency affects up to 52% of pregnant women worldwide.<ref name=":16">Template:Cite journalTemplate:Dead link</ref>
The prevalence of iron deficiency as a cause of anemia varies among countries; in the groups in which anemia is most common, including young children and a subset of non-pregnant women, iron deficiency accounts for a fraction of anemia cases in these groups (25% and 37%, respectively).<ref>Template:Cite journal</ref> Iron deficiency is common in pregnant women.<ref>Template:Cite journal</ref>
Within the United States, iron-deficiency anemia affects about 2% of adult males, 10.5% of White women, and 20% of African-American and Mexican-American women.<ref>Template:Cite journal</ref> A study in 2024 suggests that nearly 1 in 3 Americans may have undiagnosed iron deficiency, which can cause fatigue, brain fog, and concentration problems. The analysis of data from over 8,000 U.S. adults found that 14% had low iron levels, known as absolute iron deficiency, while 15% had normal iron levels but their bodies couldn’t effectively use the mineral, a condition called functional iron deficiency.<ref>Template:Cite journal</ref>
A map provides a country-by-country listing of what nutrients are fortified into specified foods. Some of the Sub-Saharan countries shown in the deaths from iron-deficiency anemia map from 2012 are as of 2018 fortifying foods with iron.<ref name="FFI" />
ReferencesEdit
External linksEdit
Template:Medical condition classification and resources
- The Importance of Iron – From IronTherapy.Org
- Interactive material on Iron Metabolism Template:Webarchive – From IronAtlas.com
- Approach to chronic anemia : https://ashpublications.org/hematology/article/2012/1/183/83845/How-to-approach-chronic-anemia
- Handout: Iron Deficiency Anemia – From the National Anemia Action Council
- NPS News 70: Iron deficiency anaemia: NPS – Better choices, Better health – From the National Prescribing Service
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