Clinician Fact Sheet: Iron
Clinician Fact Sheet
Iron
September 2001; Volume 4; S1-S2
Although most commonly used to treat iron deficiency, recent attention has focused on the possible association between high iron stores and heart disease. For instance, the incidence of heart disease seems to increase in women when monthly periods cease. In addition, researchers have suggested a possible association between low iron levels of people living in developing countries and their lower rates of heart disease. However, data from recent clinical studies have not provided convincing support for this relationship.1
Recommended Dietary Allowances (RDA)
6 mg/d for children 0-6 mo 15 mg/d for females 11-50 y
10 mg/d for children 6 mo-10 y 10 mg for males 19 y and older
12 mg/d for males 11-18 y 10 mg for females 51 y and older
Food Sources
Dietary sources of iron include beef, poultry, pork, shellfish, fish, fortified cereals, soybeans, beans, raisins, and cooked asparagus, broccoli, cabbage, peppers, spinach, and tomatoes.
Formulation and Dosage
• Iron supplements come in ferrous and ferric forms. The ferrous form is absorbed better by the body and is preferred for use in iron deficiency.
• The amount of elemental iron varies depending upon the iron formulation: 1 g of ferrous gluconate = 120 mg (12%) elemental iron; 1 g of ferrous sulfate = 200 mg (20%) elemental iron; 1 g of ferrous fumarate = 330 mg (33%) elemental iron.
• Although overall dietary iron absorption usually ranges from 10% to 15%, absorption can vary significantly depending on the person and the iron needs of the body.
• In iron deficiency anemia: adults, 50-100 mg elemental iron tid for six months; children, 4-6 mg/kg/d in three divided doses for six months. Iron deficiency in individuals with chronic bleeding disorders requires continuous iron therapy.
Mechanism of Action
• Iron is an essential trace mineral found in hemoglobin in red blood cells and myoglobin in muscle cells where it is required for oxygen and carbon dioxide transport.
• Iron is an electron carrier in cytochromes, is found in enzymes that assist biochemical reactions in cells, and is involved in the regulation of dopamine activity.
Clinical Uses
• To treat and prevent iron deficiency and iron deficiency anemia.
• To treat attention deficit disorder.
• To improve athletic performance in athletes who are iron deficient.
• To treat oral canker sores; the diets of patients with recurrent aphthous ulcers often are deficient in iron and a number of other nutrients.
• To treat Crohn’s disease.
• To treat infertility in women who are iron deficient.
• To treat the consequences of menorrhagia.
Adverse Effects/Toxicity
• When normal iron storage sites are full, iron can accumulate in body tissues and organs, damaging the liver and intestines.
• The estimated lethal dose of iron is 180-300 mg/kg; however doses as low as 60 mg/kg also have been lethal and doses of 30 mg/kg have been associated with acute toxicity.
• Iron is the most common cause of pediatric poisoning deaths and acute toxicity can occur in children from ingestion of medicinal iron. Doses of 1-3 g of iron can be fatal to children younger than age six.
• Large doses of supplemental iron can cause constipation, dark stools, nausea, vomiting, and diarrhea. Adverse gastrointestinal effects may be avoided by gradually increasing to the full dose, taking the iron in divided doses, and taking supplements with meals.
• Iron overload is associated with several genetic and hemoglobin diseases, including hemochromatosis. Iron supplementation may accelerate the effects of these diseases and should be avoided.
• Because of the risks associated with iron overload, adult men and postmenopausal women who are not iron deficient should not take iron supplements.
• Individuals who require frequent blood transfusions also are at an increased risk of iron overload and should avoid iron supplements.
• Long-term use of high doses of iron can cause hemosiderosis that clinically resembles hemochromatosis.
• Iron can exacerbate peptic ulcer disease, regional enteritis, and ulcerative colitis.
Populations at Risk
• Women of childbearing age, pregnant women, older infants and toddlers, and teenage girls are at greatest risk of developing iron deficiency anemia.
• Patients with renal failure, especially those receiving dialysis, are at high risk of developing iron deficiency anemia.
• Iron deficiency is more common among women with heavy menstrual losses, minority women, women of low-income status, and women with more than one child.
• Women using an intrauterine device may have an increased risk of developing iron deficiency due to an increased risk of bleeding.
• Pregnancy increases a woman’s need for iron due to increased blood volume, increased needs of the fetus, and blood losses that occur during delivery.
• Vegetarians who exclude all animal products from their diets may need supplemental iron.
• Individuals who engage in regular intense exercise may have an increased need for iron.
Interactions/Nutrient Depletion
• Use of oral iron preparations in premature infants with low serum vitamin E levels may cause hemolysis and hemolytic anemia. Vitamin E deficiency should be corrected before administering supplemental iron.
• When taken on an empty stomach, iron may decrease the absorption of zinc, calcium, and copper.
• Low vitamin A status can limit the body’s ability to use stored iron and cause iron deficiency.
• Concomitant use of iron and vitamin C (in doses greater than 200 mg) can increase iron absorption. Separate doses to limit toxicity
• Iron absorption is decreased with concomitant use of antacids, calcium, soy, caffeine, proton pump inhibitors, ACE inhibitors, or H2-blockers, and in individuals with malabsorption diseases.
• Concomitant use of iron decreases the absorption of ciprofloxacin, fluoroquinolones, methyldopa, norfloxacin, ofloxacin, penicillamine, and thyroxine replacement therapy.
• Concomitant administration decreases absorption of iron and tetracyclines.
• Use of chloramphenicol may delay response to iron therapy.
• Concomitant administration with oral iron enhances the effect of erythropoietin on hemoglobin.
• The guaiac test for occult fecal blood may give a false-positive result in individuals taking iron.
Reference
1. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes for vitamin A, vitamin K, arsenic, boron, chromium, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. Washington, DC: National Academy Press; 2001.
Resources
Pelton R, et al. Drug-Induced Nutrient Depletion Hand-book. Hudson, OH: Lexi-Comp; 1999.
Iron. Facts about Dietary Supplements. Office of Dietary Supplements. National Institutes of Health. Available at: www.cc.nih.gov/ccc/supplements/iron.pdf. Accessed: July 30, 2001.
Natural Medicines Comprehensive Database [database online]. Stockton, CA: Therapeutic Research Center, Inc., 2000.
September 2001; Volume 4; S1-S2
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