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Iron (Fe)

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Taking medicines, such as chloramphenicol, birth control pills, corticotropin, estrogen, aspirin, and iron supplements.
  • Using some herbal remedies, especially St. John's wort and saw palmetto.
  • Taking vitamin B12 supplements in the 48 hours before the iron test.
  • Not getting enough sleep (sleep deprivation).
  • Being under a lot of stress.
  • Having a blood transfusion in the past 4 months.

What To Think About

  • Taking iron supplements for tiredness can mask an iron problem. Talk to your doctor before taking iron supplements.
  • Iron levels change during the day. Iron tests are best done in the morning, when iron levels are highest.
  • The results of an iron test are also checked with results of a complete blood count (CBC), ferritin, and transferrin tests. The ferritin test is often better than an iron test to see if iron deficiency is present. An iron test and ferritin test are often done at the same time.
  • A test called the siderocyte stain test checks the number of red blood cells that have particles of iron not bound to hemoglobin (siderocytes). Normally, very low numbers of siderocytes are present in blood. High levels of siderocytes in adults may mean that a type of anemia, iron overload, lead poisoning, hemochromatosis, or a severe infection is present.
  • When iron deficiency anemia is diagnosed, the source of the anemia must be found and treated. Iron deficiency can be caused by long-term (chronic) blood loss from heavy menstrual bleeding, pregnancy, not enough iron in the diet, or bleeding inside the intestinal tract (from ulcers, colon polyps, colon cancer, hemorrhoids camera.gif, or other conditions). In rare cases, too much iron may be lost through the skin (because of a disease such as psoriasis camera.gif) or in the urine. Iron deficiency anemia can be easily treated with iron supplements, but the key is to identify it and stop the iron loss.
  • Hemochromatosis can be treated with medicines to help the body get rid of extra iron. A procedure called a phlebotomy can also be done to remove iron from the body.


  1. Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

Other Works Consulted

  • Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.

  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

  • Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.

ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerJoseph O'Donnell, MD - Hematology, Oncology
Last RevisedAugust 6, 2012

WebMD Medical Reference from Healthwise

Last Updated: August 06, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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