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Iron Tests

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Also known as: Fe Tests; Iron Indices
Formal name: Iron Tests

At a Glance

Why Get Tested?

To evaluate your body's current level of iron

When to Get Tested?

When your doctor suspects that you may have too little or too much iron in your system

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

Your doctor may request that you fast for 12 hours prior to some iron tests; in this case, only water is permitted.

The Test Sample

What is being tested?

Iron is an essential nutrient to maintain life. It is needed in small quantities to help form normal red blood cells (RBCs) and is a critical part of hemoglobin, the protein in RBCs that binds oxygen in the lungs and releases it as blood circulates to other parts of the body.

Iron tests are ordered to evaluate the amount of iron in the body by measuring several substances in the blood. These tests are often ordered at the same time, where together, the results are considered in establishing the diagnosis and/or monitoring iron deficiency or iron overload.

  • Serum iron measures the level of iron in the liquid portion of the blood.
  • TIBC (total iron-binding capacity) measures all of the proteins in the blood that are available to bind with iron, including transferrin.
  • UIBC (unsaturated iron-binding capacity) measures the portion of transferrin that has not yet been saturated. UIBC also reflects transferrin levels.
  • Transferrin saturation is a calculation that reflects the percentage of transferrin that is saturated with iron.
  • Serum ferritin reflects the amount of stored iron in the body.

Low iron levels can lead to anemia, causing decreased production of RBCs that are microcytic and hypochromic. Conversely, large quantities of iron can be toxic to the body. This occurs when too much iron is absorbed over time, leading to the accumulation of iron compounds in tissues, particularly the liver, heart, and pancreas.

Iron is normally absorbed from food and transported throughout the body by binding to transferrin, a protein produced by the liver. About 70% of the iron transported is incorporated into the production of red blood cell hemoglobin. The remainder is stored in the tissues as ferritin or hemosiderin, with additional small amounts used to produce other proteins such as myoglobin and some enzymes.

Iron deficiency may be seen with insufficient intake, inadequate absorption, or increased nutrient requirements as seen during pregnancy or with acute or chronic blood loss. Acute iron overload may often occur with excess ingestion of iron tablets, especially in children. Chronic iron overload may be due to excessive iron intake, hereditary hemochromatosis, multiple blood transfusions, and a few other conditions.

How is the sample collected for testing?

A blood sample is drawn by needle from a vein in the arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

Fasting for 12 hours before sample collection may be required. In this case, only water is permitted.

The Test

Common Questions

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Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Devkota, B. (2012 October 4). Iron. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/2085704-overview#showall through http://emedicine.medscape.com. Accessed April 2013.

Gersten, T. (Updated 2012 February 8). Serum iron. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003488.htm. Accessed April 2013.

Paruthi, S. (Updated 2012 November 7). Transferrin Saturation. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/2087960-overview through http://emedicine.medscape.com. Accessed April 2013.

Devkota, B. (Updated October 4). Iron-Binding Capacity. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/2085726-overview through http://emedicine.medscape.com. Accessed April 2013.

Spanierman, C. (Updated 2011 July 27). Iron Toxicity in Emergency Medicine. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/815213-overview through http://emedicine.medscape.com. Accessed April 2013.

Boyle, J. (Updated 2012 April 12). Pediatric Iron Toxicity. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/1011689-overview through http://emedicine.medscape.com. Accessed April 2013.

Gersten, T. (Updated 2012 February 8). Total iron binding capacity. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003489.htm. Accessed April 2013.

Gersten, T. (Updated 2012 February 8). Ferritin. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003490.htm. Accessed April 2013.

Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference, 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 594-598.

Clarke, W., Editor (© 2011). Contemporary Practice in Clinical Chemistry, 2nd Edition: AACC Press, Washington, DC. Pp 536, 597.

Elghetany MT, Banki K. Erythrocytic disorders, in Henry's Clinical Diagnosis and Management by Laboratory Methods, 22nd ed. McPhereson RA, Pincus MR, eds. Elsevier/Saunders:Philadelphia. Chapter 32, 2011.

Sources Used in Previous Reviews

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 574-577.

Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 407-408.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 634-635.

(Modified 2009 March 13). About Iron. Iron Disorders Institute [On-line information]. Available online at http://www.irondisorders.org/Disorders/about.asp through http://www.irondisorders.org. Accessed June 2009.

(Updated 2007 August 24). Dietary Supplement Fact Sheet: Iron. NIH Office of Dietary Supplements [On-line information]. Available online at http://ods.od.nih.gov/factsheets/iron.asp through http://ods.od.nih.gov. Accessed June 2009.

Rathz, D. et. al. (Updated 2009 February 02). Toxicity, Iron. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/166933-overview through http://emedicine.medscape.com. Accessed June 2009.

Chen, Y. (Updated 2009 April 05). Iron Deficiency Anemia. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000584.htm. Accessed June 2009.

Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson RA and Pincus MR, eds. Philadelphia: 2007, Pg 506-507.

(November 3, 2006) Iron Disorders Institute, Sideroblastic anemia. Available online at http://www.irondisorders.org/Disorders/Sideroblastic.asp through http://www.irondisorders.org. Accessed September 2009.

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