Transferrin receptor (soluble)

General Information

Iron uptake by cells is accomplished by the uptake of iron-binding transport complexes. These complexes bind to transferrin receptors located on the outer surface of the cell membrane and are taken up by endosomes, releasing iron into the cell cytoplasm. When a cell needs iron, receptor synthesis is increased, which facilitates the uptake of iron-containing complexes by the cell. Since iron is primarily used in the synthesis of hemoglobin, 80% of transferrin receptors are located on erythrocyte precursor cells.

The cleavage of the extracellular portion of the transferrin receptor by proteolytic enzymes results in the formation of a soluble form that circulates freely in the plasma. The concentration of circulating soluble transferrin receptor indicates the status of iron content in the body.

During iron deficiency, the synthesis of transferrin receptors on the cell membrane increases, while in high iron concentrations, the opposite is true.

However, serum ferritin determination is an important test for detecting iron deficiency, but it is an acute phase protein, the concentration of which increases not only in iron deficiency, but also in other conditions: infections, inflammation, chronic diseases, neoplastic processes.

The transferrin receptor is not an acute phase protein, therefore, its concentration does not change during other processes.

When is the survey conducted?

• In the differential diagnostics of microcytic anemias (transferrin receptor concentration increases in iron deficiency anemias, but not in anemias associated with chronic diseases)
• When diagnosing microcytic anemia in a patient with a chronic disease (e.g. rheumatoid arthritis)
• To assess anemia status when ferritin levels are normal

Material for examination: Venous blood

Preparation of the patient:  The study is conducted on an empty stomach

Interpretation of results

The concentration of soluble transferrin receptor is proportional to the iron content in the body.

An increase in the concentration of soluble transferrin receptor is characteristic of the following conditions:

• Diseases associated with increased erythropoiesis (iron deficiency anemia, hemolytic anemia)
• Diseases with ineffective erythropoiesis (megaloblastic anemia, myelodysplastic syndromes)
• Erythropoietin treatment
• People living at high altitudes above sea level

A decrease in the concentration of soluble transferrin receptor is characteristic of the following conditions:

• Diseases with reduced erythropoiesis (aplastic anemia, post-transplant anemia, chronic renal failure)
• Iron overdose

In healthy patients (who do not have chronic pathologies), the study is not prescribed for screening.

Patients with a recent history of bleeding or hemolysis may have a falsely elevated soluble transferrin receptor concentration.

The concentration of soluble transferrin receptor is increased in thalassemia and sickle cell anemia, therefore, the obtained data should be analyzed in a complex manner, together with data from other studies.