At a Glance

Why Get Tested?

Along with other iron tests, to assess your body's power to transport iron in the blood; to help diagnose iron-deficiency or atomic number 26 overload

When To Get Tested?

When you have low hemoglobin and hematocrit on a complete blood count (CBC); when your healthcare practitioner suspects yous may have too much iron (overload) or too little iron (deficiency) in the body

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

You may be instructed to accept your blood drawn in the morning and/or fast for 12 hours before the exam; in this case, just h2o is immune. Follow any instructions from your health care practitioner and/or from the laboratory performing the test.

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You may be able to discover your test results on your laboratory's website or patient portal. However, yous are currently at Testing.com. Y'all may have been directed here by your lab'due south website in order to provide yous with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in lodge to obtain your test results.

Testing.com is an honour-winning patient pedagogy website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides full general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner well-nigh your health or medical condition.

The reference ranges for your tests tin be plant on your laboratory report. They are typically found to the right of your results.

If you do not have your lab study, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a salubrious person. They are sometimes called "normal" values. By comparison your examination results with reference values, you and your healthcare provider can meet if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible weather condition or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability tin can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. Information technology is important to know that y'all must use the range supplied by the laboratory that performed your exam to evaluate whether your results are "within normal limits."

For more data, please read the article Reference Ranges and What They Mean.

What is being tested?

Transferrin is the main protein in the blood that binds to iron and transports information technology throughout the body. A transferrin test directly measures the level in the blood. Alternatively, transferrin may be measured indirectly (or converted by calculation) and then that its level is expressed as the amount of iron information technology is capable of binding. This is called the total iron binding capacity (TIBC).

Iron is an essential nutrient that, amid other functions, is necessary for the product of healthy red blood cells (RBCs). It is a critical part of hemoglobin, the protein in RBCs that binds oxygen in the lungs and releases oxygen as blood circulates to other parts of the torso. The torso cannot produce atomic number 26 and must absorb it from the foods we eat or from supplements.

Ordinarily, iron is transported throughout the torso by transferrin, which is produced by the liver. In healthy people, most fe is incorporated into the hemoglobin within RBCs. The remainder is stored in the tissues as ferritin or hemosiderin, with additional small amounts used for other purposes (e.thou., to produce other proteins such as myoglobin and some enzymes).

The transferrin examination, TIBC, UIBC, and transferrin saturation, forth with other iron tests, help evaluate the amount of fe in the body past measuring several substances in the blood. These tests are often ordered at the same time and the results interpreted together to help diagnose and/or monitor fe deficiency or iron overload.

  • Serum iron test—measures the full amount of atomic number 26 in the liquid portion of the claret, nearly all of which is leap to transferrin.
  • Transferrin test—directly measures the level of transferrin in the blood. The level depends upon liver function and a person's nutritional status. Transferrin is a protein that may decrease during whatever inflammatory process and is referred to equally a negative acute phase reactant.
  • TIBC (total iron-bounden capacity)—measures the total amount of iron that can be jump past proteins in the blood. Since transferrin is the main iron-binding protein, the TIBC test is a good indirect measurement of transferrin availability—the corporeality of transferrin that is available to bind to iron. (Note: Though TIBC is a reflection of the corporeality of transferrin bachelor, TIBC and transferrin are not synonymous.)
  • UIBC (unsaturated iron-binding capacity)—this test determines the reserve capacity of transferrin, i.e., the portion of transferrin that has not however been saturated with iron.
  • Transferrin saturation— dividing the iron concentration by the TIBC produces an estimate of how many of transferrin fe-binding sites are occupied; this is called the transferrin saturation. Nether normal weather condition, transferrin is typically one-third saturated with atomic number 26. This means that about two-thirds of its capacity is held in reserve. (Less commonly, the iron concentration may be divided by the transferrin concentration, non the TIBC. This similar estimate is usually called the transferrin index.)
  • Ferritin—measures the level of ferritin, a protein made by nearly all cells in response to increased iron. The ferritin level reflects the full trunk iron. Information technology will be low when there is iron deficiency and high when there is an excess of iron in the body.

When the level of fe is insufficient to meet the body's needs, the level of iron in the blood drops and iron stores are depleted. This may occur because:

  • In that location is an increased need for iron, for example during pregnancy or babyhood, or due to a status that causes chronic blood loss (e.g., peptic ulcer, colon cancer)
  • Not enough iron is consumed (either foods or supplements)
  • The torso is unable to absorb atomic number 26 from the foods eaten in conditions such as celiac illness

Bereft levels of circulating and stored iron may somewhen atomic number 82 to iron deficiency anemia (decreased hemoglobin and hematocrit, smaller and paler blood-red cells). In the early stage of fe deficiency, no physical effects are unremarkably seen and the amount of atomic number 26 stored may be significantly depleted earlier whatever signs or symptoms of iron deficiency develop. If a person is otherwise healthy and anemia develops over a long menses of time, symptoms may not announced before the hemoglobin in the blood drops below the lower limit of normal.

However, as the iron deficiency progresses, symptoms eventually brainstorm to appear. The nigh common symptoms of anemia include fatigue, weakness, dizziness, headaches and pale peel.

Conversely, also much iron can be toxic to the body. Iron storage and ferritin levels increase when more atomic number 26 is absorbed than the body needs. Absorbing also much iron over time tin lead to the progressive buildup of atomic number 26 compounds in organs and may somewhen crusade their dysfunction and failure. An example of this is hemochromatosis, a rare genetic illness in which the body absorbs and builds up as well much fe, even on a normal diet. Additionally, atomic number 26 overload can occur when a person undergoes repeated blood transfusions.

Common Questions

How is it used?

The transferrin, total atomic number 26-binding capacity (TIBC) or unsaturated iron-binding capacity (UIBC) test may be used along with other iron tests to appraise the amount of iron circulating in the blood, the full capacity of the claret to transport iron, and the amount of stored iron in the body. Testing may also aid differentiate diverse causes of anemia.

Iron tests are often ordered together, and the results of each can help place atomic number 26 deficiency, iron deficiency anemia, or besides much iron in the body (overload).

When is information technology ordered?

These tests may be ordered forth with other iron tests when results from a routine complete blood count (CBC) show that a person'south hemoglobin and hematocrit are low and their cherry blood cells are smaller and paler than normal (microcytic and hypochromic), suggesting atomic number 26 deficiency anemia even though other clinical symptoms may not have developed yet.

Iron tests may be ordered when a person develops signs and symptoms of anemia such every bit:

  • Chronic fatigue/tiredness
  • Dizziness
  • Weakness
  • Headaches
  • Pale pare (pallor)

Testing may be ordered when iron overload is suspected. Signs and symptoms of iron overload will vary from person to person and tend to worsen over time. They are due to iron accumulation in the claret and tissues. These may include:

  • Joint pain
  • Fatigue, weakness
  • Weight loss
  • Lack of energy
  • Abdominal pain
  • Loss of sex activity drive
  • Organ damage, such equally in the middle and/or liver

Testing is too ordered when in that location is a case of suspected iron poisoning. This is most common in children who accidentally overdose with vitamins or other supplements containing iron.

What does the examination effect mean?

The results of transferrin tests, TIBC, or UIBC are usually evaluated in conjunction with other iron tests. A summary of the changes in iron tests seen in diverse diseases of iron status is shown in the table below.

Disease Iron TIBC/Transferrin UIBC %Transferrin

Saturation

Ferritin
Iron Deficiency Low High High Low Low
Hemochromatosis/Hemosiderosis High Low Low High Loftier
Chronic Illness Low Low/Normal Low/Normal Low/Normal High/Normal
Hemolytic Anemia Loftier Normal/Low Low/Normal High High
Sideroblastic Anemia Normal/High Normal/Depression Low/Normal Loftier Loftier
Iron Poisoning High Normal Low High Normal

Iron deficiency
The early stage of iron deficiency is the slow depletion of iron stores. This ways there is yet enough atomic number 26 to make red cells just the stores are being used up without adequate replacement. The serum atomic number 26 level may exist normal in this phase, but the ferritin level will be low.

Equally iron deficiency continues, all of the stored iron is used and the torso tries to compensate by producing more transferrin to increase iron ship. The serum iron level continues to decrease and transferrin and TIBC and UIBC increase. As this stage progresses, fewer and smaller red claret cells are produced, eventually resulting in fe deficiency anemia. Transferrin saturation is decreased with iron deficiency.

Iron overload
If the fe level and transferrin saturation are high, the TIBC, UIBC and ferritin are normal and the person has a clinical history consistent with iron overdose, then it is likely that the person has atomic number 26 poisoning. Fe poisoning occurs when a big dose of iron is taken all at one time (acute) or over a long menstruum of time (chronic). Iron poisoning in children is almost always acute, occurring in children who ingest their parents' iron supplements. In some cases, acute iron poisoning tin be fatal.

A person who has mutations in the HFE gene is diagnosed with hereditary hemochromatosis. However, while many people who have hemochromatosis volition accept no symptoms for their entire life, others will starting time to develop symptoms such as joint pain, abdominal hurting, and weakness in their 30's or forty's. Men are affected more than often than women considering women lose blood during their reproductive years through catamenia.

Atomic number 26 overload may also occur in people who accept hemosiderosis and in those who take had repeated transfusions. This may occur with sickle cell anemia, thalassemia major, or other forms of anemia. The iron from each transfused unit of blood stays in the trunk, eventually causing a big buildup in the tissues. Some persons with alcoholism and with chronic liver disease too develop iron overload.

Is in that location annihilation else I should know?

Contempo blood transfusions tin impact test results as can iron injections or transfused iron. Multiple claret transfusions tin sometimes lead to iron overload.

A high TIBC, UIBC, or transferrin usually indicates iron deficiency, simply they are also increased in pregnancy and with the utilise of oral contraceptives.

A low TIBC, UIBC, or transferrin may also occur if someone has malnutrition, inflammation, liver disease, or nephrotic syndrome. However, the tests are commonly not used to assess these conditions.

How is transferrin saturation calculated?

The calculation is:

Transferrin saturation (%) = (Serum iron level x 100%) / TIBC

TIBC measures the total amount of iron that can be spring by proteins in the blood. Since transferrin is the principal iron-binding protein, the TIBC test is a skilful indirect measurement of transferrin availability—the amount of transferrin that is bachelor to bind to iron.

In healthy individuals, transferrin is one-third saturated with iron. This means that there is near two-thirds held in reserve. In iron deficiency, all of the stored fe is used and the trunk tries to compensate past producing more transferrin to increase atomic number 26 transport. While the serum iron level continues to decrease, the transferrin level increases. Thus, the corporeality of transferrin available to bind iron (TIBC) increases and the amount of transferrin saturated with atomic number 26 (i.eastward., percent transferrin saturation) decreases.

What other factors touch on the transferrin level?

Transferrin is a protein that may decrease during any inflammatory process and is referred to every bit a negative astute phase reactant. Chronic inflammation, infections, and malignancies may cause changes in transferrin levels.

Are there other things that crusade anemia besides iron deficiency?

Yes, at that place are numerous causes of anemia. However, iron deficiency is one of the nearly common. If iron tests rule out fe deficiency, some other source for the anemia must be found.

Health Professionals – LOINC

Logo for LOINC from RegenstriefLOINC Observation Identifiers Names and Codes (LOINC®) is the international standard for identifying wellness measurements, observations, and documents. It provides a common linguistic communication to unambiguously place things y'all tin mensurate or discover that enables the exchange and aggregation of clinical results for intendance delivery, outcomes management, and research. Acquire More.

Listed in the table below are the LOINC with links to the LOINC item pages. Please note when you click on the hyperlinked code, y'all are leaving Testing.com and accessing Loinc.org.

LOINC LOINC Display Proper noun
3034-6 Transferrin [Mass/Vol]
22674-half dozen Transferrin [Moles/Vol]
2501-5 Iron bounden capacity.unsaturated [Mass/Vol]
22753-viii Iron binding capacity.unsaturated [Moles/Vol]
2500-seven Atomic number 26 bounden capacity [Mass/Vol]
14800-7 Iron binding capacity [Moles/Vol]
2505-half dozen Atomic number 26/Fe binding chapters.total [Mass ratio]
39778-6 Atomic number 26/Atomic number 26 binding capacity.total [Molar ratio]
2502-3 Iron saturation [Mass fraction]
14801-v Iron saturation [Molar fraction]

Related Content

View Sources

Sources Used in Current Review

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Paruthi, Due south. (2015 January 14 Updated). Transferrin Saturation. Medscape Drugs and Diseases. Available online at http://emedicine.medscape.com/commodity/2087960-overview. Accessed on May 2017.

Harper, J. and Conrad, M. (2015 Nov vii Updated). Iron Deficiency Anemia. Medscape Drugs and Diseases. Available online at http://emedicine.medscape.com/commodity/202333-overview. Accessed on May 2017.

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