Interpretation
Soluble transferrin receptor (sTfR) concentrations are inversely related to iron status; sTfR elevates in response to iron deficiency and decreases in response to iron repletion.
Its primary role is in the context where iron deficiency may be masked with ferritin elevation into the reference interval (15-100 ug/L) in the presence of concomitant inflammation (CRP > 20mg/L).
Inflammation may elevate ferritin whilst lowering iron and saturation. sTfR, however is not an acute phase reactant and not affected by inflammation or chronic disease.
Cautions:
Patients with haemolysis and recent blood loss may have falsely elevated sTfR levels.
sTfR is also elevated in patients with increased red cell turnover, including those with thalassemia and sickle cell disease and other haemoglobinopathies.
A reticulocyte count may assist with interpretation in some cases. Other confounding conditions may include other erythroid malignancies and lymphoma.
It may also be falsely lowered in aplastic anaemia, chronic renal failure and patients on chemotherapy.
Reference Intervals
0.76 – 1.76 mg/L
Raised sTfR is supportive of iron deficient erythropoiesis, especially when concomitant inflammation may be masking iron stores.
Non-raised sTfR is not supportive of iron-deficient erythropoiesis.
Test Method
Nephelometric immunoassay on Siemens BNII.
