To detect iron deficiency anemia and distinguish it from anemia caused by chronic illness or inflammation
Soluble Transferrin Receptor
Soluble Transferrin Receptor
Also Known As
sTfR
Transferrin Receptor
TfR
Serum Transferrin Receptors
Formal Name
Soluble Transferrin Receptor
This article was last reviewed
on
This article waslast modified
on November 5, 2017.
At a Glance
Why Get Tested?
When To Get Tested?
When iron deficiency anemia is suspected
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
None
Accordion Title
Common Questions
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How is it used?
The soluble transferrin receptor (sTfR) test is primarily ordered to help distinguish between anemia that is caused by iron deficiency and anemia that is caused by inflammation or a chronic illness (so-called anemia of chronic disease or inflammation). It is not a routine test but may be ordered if other tests that evaluate the amount of iron in the body do not provide conclusive information.
Typically, a group of iron tests is ordered to evaluate iron availability if a person has anemia and/or if iron deficiency is suspected. These tests may include iron, transferrin, TIBC (total iron-binding capacity, which is either measured or calculated based on the level of transferrin), transferrin saturation (calculated based on levels of iron and TIBC), and ferritin.
Ferritin is usually the preferred test to evaluate stored iron, but it is an acute phase reactant, which means that it may be increased with inflammation or with chronic diseases such as autoimmune disorders, some cancers, and chronic infections. In these cases, ferritin may not be a good measure of stored iron. Since sTfR is not an acute phase reactant, it may be ordered as an alternative to ferritin if a chronic illness is present or suspected.
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When is it ordered?
The soluble transferrin receptor test is not routine but may be ordered along with or in follow up to other iron tests when a person has symptoms of anemia such as:
- Weakness, fatigue
- Lack of energy
- Paleness
This test may also be ordered when a complete blood count (CBC) shows decreased hemoglobin and small red blood cells (low MCV).
It may be ordered when a person has a normal or near normal ferritin level, but iron deficiency is still suspected. It may be ordered as an alternative to ferritin when a person has a chronic illness and/or inflammation is present or suspected.
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What does the test result mean?
The level of soluble transferrin receptor (sTfR) will be increased with iron deficiency. If the sTfR level is elevated in someone with anemia, then it is likely that the person has iron deficiency anemia. If the level is within the normal range, then it is more likely that the person's anemia is due to another cause, such as chronic disease or inflammation.
A decreasing sTfR level indicates an increase in iron reserve in a person being treated with iron supplements. A low level of sTfR may be seen with hemochromatosis (a condition associated with iron overload), but the test is not usually used to monitor this condition.
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Is there anything else I should know?
Those of African American descent may have moderately increased sTfR levels, as will those who live at higher elevations.
Testing may not be useful in those who have inherited disorders that affect hemoglobin production or function, such as thalassemia or sickle cell anemia. Test results may be elevated in those with red blood cell breakage (hemolysis) or recent blood loss and will not be accurate in those who have had a recent blood transfusion.
An elevated sTfR level is not as specific for iron deficiency as is, for example, a very low level of ferritin.
When a person is not iron deficient, the amount of sTfR present in the blood reflects the rate of red blood cell production by the bone marrow. Soluble transferrin receptor testing is not routinely performed to evaluate this process.
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Why not just order an iron test?
A single iron test does not provide the full picture of the amount of iron that a person has stored and available. It is usually necessary to evaluate the results of several related iron tests together. Ferritin is usually the preferred test to evaluate stored iron, but it is an acute phase reactant, meaning that it may be increased with inflammation or chronic diseases. In these cases, ferritin may not be a good measure of stored iron. The soluble transferrin receptor test is not a routinely order test, but since it is not an acute phase reactant, it may be ordered as an alternative to ferritin to evaluate stored iron when a chronic illness is present or suspected.
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Can I have iron deficiency if I feel fine?
Yes. Early deficiency usually will not cause any symptoms and when symptoms do emerge, they may be mild or nonspecific enough – such as fatigue – that they are attributed to something else.
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Can my test for sTfR be performed in my doctor's office?
No. Testing requires specialized equipment and is not offered by every laboratory. Your test may be sent to a reference laboratory.
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Why does my doctor want to send a second sTfR test to the same laboratory as the first test?
Test methods and reference (normal) ranges for sTfR will vary slightly from laboratory to laboratory. Your healthcare provider may prefer to send your samples to the same laboratory to make results more directly comparable.
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Should I just take iron supplements?
You should consult with your healthcare provider first. If you are anemic and/or at risk of anemia, then supplements may be useful. Excess iron in the body can cause health problems.