Soluble Transferrin Receptor
Soluble transferrin receptor (sTfR) is a marker that reflects how much iron your cells are demanding to make red blood cells. Levels rise when cells are hungry for iron.
sTfR is helpful because, unlike ferritin, it is not strongly affected by inflammation, so it can clarify iron status when inflammation muddies other markers. It's often used to help tell true iron deficiency apart from anemia of chronic disease. It adds a valuable angle when the standard iron panel is hard to interpret.
A high sTfR usually indicates increased cellular demand for iron, commonly seen in iron deficiency. It can also rise when red blood cell production is ramped up for other reasons. It's most informative combined with ferritin and the clinical picture.
A low or normal sTfR generally suggests iron demand is being met, which can help rule iron deficiency less likely. It's interpreted alongside your other iron markers.
Assays and reference ranges for sTfR vary between labs, so results aren't always directly comparable. A clinician can tell you whether this test is useful for you and how to read it.
Sources
- Iron · Health Professional Fact Sheet, NIH Office of Dietary Supplements
- Iron-Deficiency Anemia · MedlinePlus
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.