Measurement of soluble transferrin receptor is used to assess iron adequacy in patients who may have inflammation, infection, neoplasia, or other chronic disease, situations in which the ferritin concentration may not correlate with the true iron status in the body.
Transferrin belongs to the beta globins and is a glycoprotein with a short (7 days) half-life synthesized in the liver. Transferrin facilitates cellular uptake of iron by transferring the iron from the intestinal mucosa to the iron storage sites and the hemoglobin synthesis sites in the body (bones, muscles, erythrocytes, lymphocytes). Transferrin allows iron storage by binding to two types of transferrin receptors (type 1 and type 2) at the iron storage sites. 80% of the transferrin receptors are found in erythroid tissue (bone marrow precursor cells) although these receptors are present in almost all body tissues. During endocytosis via the transferrin receptors, iron is transferred into the cells. The most important stimuli for regulating serum transferrin receptor concentration are the cellular requirements in iron and the rate of proliferation in erythroid tissue. Therefore, the serum transferrin receptor level can be used as a sensitive indicator of early iron deficiency in tissues.
The soluble transferrin receptor increases in iron deficiency and usually remains unaffected in chronic disease conditions. Generally, the soluble transferrin receptor should be measured in conjunction with other tests indicating the state of iron in the body, including ferritin, total iron binding capacity (TIBC) and serum iron (Fe).
Screening for soluble transferrin receptor helps:
- To establish a distinction between iron deficiency anemia and chronic anemia.
- Assess the state of the body's iron and iron stores in tissues, in combination with ferritin levels.
- In determining the cause of iron deficiency in inflammatory conditions and chronic anemia, because transferrin levels are not affected by the acute phase response.
- It may help to evaluate erythropoiesis in patients receiving erythropoietin therapy.
- Evaluation of iron during pregnancy because the results are not affected by changes during pregnancy.
- Transferrin soluble receptor screening cannot be used to assess iron levels when there are coexisting conditions associated with significantly increased erythropoiesis (such as megaloblastic anemia and thalassemia).
- Also, this test is not as sensitive and specific as ferritin measurement to differentiate iron-deficiency anemia from chronic anemia in elderly patients with anemia.
Possible Interpretations of Pathological Values
- Increase: Tissue iron deficiency states, with an increase proportional to the severity of the anemia. Also in: hemolytic anemia, hereditary spherocytosis, megaloblastic anemia (caused by vitamin B12 and folic acid deficiency), myelodysplastic syndromes, polycythemia, Mediterranean anemia.
- Decrease: Aplastic anemia
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
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