Soluble transferrin receptors and iron deficiency, a step beyond ferritin. A systematic review

Iron deficiency is a common disorder; it can also be the first indicator of significant gastrointestinal pathology. Total iron stores are evaluated by ferritin measurement, but this is often difficult, as coexistent disease can obscure ferritin results. Bone marrow (BM) examination was previously felt to be superior to all known serological markers of iron status, but it has a number of disadvantages. The validity of measurement of soluble transferrin receptors (sTfR) as a surrogate marker of BM iron stores has been the subject of various studies so far.

To critically review the use of sTfR as a marker for the evaluation of iron stores.

A systematic computerised literature search, in order to identify studies that compared sTfR measurement against BM iron stain.

Twenty prospective studies were identified, of which nine fulfilled the inclusion criteria (sTfR measurement in anaemic adults alongside BM iron staining). For a total of 979 patients, a different sTfR reference range was used, but levels of 2.5 mg/L (29.5 nmol/L) were consistently used as the threshold for iron-deficiency anaemia resulting in good specificity and sensitivity.

The use of sTfR improves the clinical diagnosis of iron deficiency anaemia, especially in the presence of coexisting chronic disease or gastrointestinal malignancies. The safety and cost-effectiveness of a ferritin/sTfR-based approach to exclude gastrointestinal cancer in the presence of iron deficiency has to be proven with a prospective, well standardised, multicentre trial or a meta-analysis.