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Overview of the Iron Absorption Test

written by: Cyndi Root•edited by: Emma Lloyd•updated: 7/2/2010

Iron deficiency is a widespread problem, caused often by gastrointestinal bleeding. Determining the cause of abnormal bleeding is the first step to replacing iron stores. The iron absorption test helps discover causes of iron deficiency and aid in discovering the best iron replacement.

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    The iron absorption test is administered in order to discover the cause of an iron deficiency. Discovering which preparation or iron supplementation is most adaquate to stimulate a patient to absorb iron is also a goal of the test. Iron is a metal, used by the body to transport oxygen to tissue and muscles, catalyze enzymes and is involved in cell growth and diffentiation. Iron is taken up in the gastrointestinal tract, absorbed by the intestines and gastrointestinal problems are the leading cause of blood loss and anemia. A host of problems can result from poor iron presence including cognitive problems. The absorption test can define which patients respond poorly to oral iron supplementation in the short and long term.

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    Absorption Pathways

    Inadequate iron absorption can be due to a variety of problems and the mechanism or mechanisms must be carely uncovered and treated. Normally, iron is taken into the body nutritionally, absorbed in the proximal intestine. Red meat type nutrition (heme) and white meat type nutrition including vegetables and cereals (non-heme) differ in degrading and uptake pathways. Iron absorption for heme nutrition is not as well understood as non-heme nutrition. The body regulates iron concentrations by either sensing high or low stores. The liver produces hepcidin to increase iron absorption. Appropriate levels of hepcidin have proven vital to repairing iron absorption and normal iron homeostasis.

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    The Procedure

    Baseline serum iron, transferrin, and ferritin are measured first in order to quantify iron levels before the test. The patient will have fasted for 9-12 hours before the test. A preparation will be selected, possibly a ferrous sulfate, ferrous gluconate, ferrous phyrophosphate, ferrous hydroxide, ferrous citrate or ferrous fumarate and administered orally. Two to four hours later, blood will be drawn again for testing. Individuals' absorption of iron will vary according to many factors, like pH of the intestines and the type of compound and amount used.

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    The Cause is the First Step to Treatment

    This test is safe and simple, can differentiate between types of anemia and iron deficiencies, and can predict who responds to treatment. For some people, however, who over absorb iron, the iron absorption test may not be indicated. Damage to lipids, proteins, carbohydrates, and nucleotides from free radicals could prove threatening due to an iron overdose. Iron deficiency afflicts many of the world's population and finding the cause with an iron absorption test is the first step to replacing iron stores most efficiently. The body will recycle iron and apply it bodily processes. However, if there is bleeding or a leak in blood flow as is usually the case, progressive deterioration will follow. The absorption test can help uncover the leak and inform the physician as to which compound of supplemental iron should be administered.