iron 59


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iron

 (Fe) [i´ern]
a chemical element, atomic number 26, atomic weight 55.847. (See Appendix 6-1.) Iron is chiefly important to the human body because it is the main constituent of hemoglobin, cytochrome, and other components of respiratory enzyme systems. A constant although small intake of iron in food is needed to replace erythrocytes that are destroyed in the body processes. Most iron reaches the body in food, where it occurs naturally in the form of iron compounds. These are converted for use in the body by the action of the hydrochloric acid produced in the stomach. This acid separates the iron from the food and combines with it in a form that is readily assimilable by the body. Vitamin C enhances absorption of iron, and alkalis hamper absorption.
Iron Deficiencies. The amount of new iron needed every day by the adult body is about 18 mg. A child needs more in proportion to weight. Although these amounts are very small, iron deficiencies may cause serious disorders. Three stages of iron deficiency are distinguished: iron depletion or prelatent iron deficiency, in which bodily stores are mildly depleted but no change in hematocrit or serum iron levels is detectable; latent iron deficiency, in which the serum iron level has dropped but the hematocrit is unchanged and there is no anemia; and iron deficiency anemia, a serious condition characterized by low to absent iron stores, low hematocrit, and other blood abnormalities. A great loss of blood, such as may result from bleeding ulcers, hemorrhoids, or injury, is the most common cause of a deficiency of iron. Women who lose much blood in menstruation may have to supplement their diet with iron-rich food. Iron deficiency sometimes occurs in pregnancy as a result of increased demands on the mother's blood. It may also occur in infants, since milk contains little iron. Although babies are born with an extra supply of hemoglobin, by the age of 2 or 3 months they need iron-rich food to supplement milk.

Iron preparations, such as ferrous sulfate, may be necessary in the treatment of iron deficiency anemia; they should be administered after meals, never on an empty stomach. The patient should be warned that the drugs cause stools to turn dark green or black. Overdosage may cause severe systemic reactions.

An acute iron deficiency may warrant parenteral administration of an iron supplement. Hypersensitivity to iron supplements often occurs in patients with other known allergies. In other patients the parenteral administration of iron can cause vomiting, chills, fever, headache, joint pain, and urticaria.
Food Sources of Iron. Liver is the richest source of iron; 200 g (6 ounces) of liver contains a whole day's supply for an adult. Other iron-rich foods include lean meat, oysters, kidney beans, whole wheat bread, kale, spinach, egg yolk, turnip greens, beet greens, carrots, apricots, and raisins.
Iron metabolism. Uptake of heme iron or ferrous iron occurs in the intestine. From the intestine, iron is transported on transferrin to the liver or the bone marrow. Transferrin binds to red blood precursors in the bone marrow and delivers iron for incorporation into hemoglobin. Red blood cells in the circulation contain 60 percent to 80 percent of body iron. Old red blood cels are destroyed in the spleen. The iron is bound to transferrin for recirculation. Approximately 20 percent to 30 percent of iron is stored in the form of hemosiderin in the spleen, liver, and bone marrow. The remaining iron is in the respiratory enzymes of somatic cells. Iron is lost by desquamation of skin and intestinal cells. From Damjanov, 2000.
iron 59 a radioisotope of iron having a half-life of 44.5 days; used in ferrokinetics tests to determine the rate at which iron is cleared from the plasma and incorporated in red blood cells. Symbol 59Fe.
iron dextran a complex of iron and dextran of low molecular weight; administered intravenously or intramuscularly as a hematinic.
iron poisoning poisoning from ingestion of excessive iron or iron-containing compounds, such as in children who eat iron supplement tablets like candy; symptoms include ulceration of the gastrointestinal tract, vomiting, vasodilation with shock, metabolic acidosis, liver injury, and coagulation disturbances.
iron storage disease hemochromatosis.
iron sucrose a complex of ferric hydroxide, Fe(OH)3, in sucrose; used intravenously to treat iron deficiency anemia in hemodialysis patients receiving supplemental erythropoietin therapy.

i·ron 59

(ī'ron),
An iron isotope; a gamma and beta emitter with a half-life of 44.51 days; used as tracer in the study of iron metabolism, determination of blood volume, and in blood transfusion studies.

iron 59

(ī'ŏrn)
An iron isotope; a gamma and beta emitter with a half-life of 44.51 days; used as tracer in study of iron metabolism, determination of blood volume, and in blood transfusion studies.