The soluble transferrin receptor, a marker of iron demand in the tissues.
Soluble transferrin receptor, or sTfR, is a protein released into the blood by cells that are taking up iron. When cells are short of iron, they make more receptors, so more of the soluble form appears in the blood.
It is measured in serum and is a sensitive marker of how much iron your tissues are actually getting, rather than how much is stored.
sTfR rises when the body is iron deficient, often before stores are fully exhausted. A key advantage is that, unlike ferritin, it is not pushed up by inflammation, so it stays reliable when someone is unwell.
This makes it useful for telling apart true iron deficiency from the anaemia of chronic disease, especially when ferritin results are hard to interpret.
Aniva reads your result against research-backed ranges, not just the lab's wide normal. The reference shown below is specific to this biomarker.
Typical adult guidance, assay dependent:
| Result | Range |
|---|---|
| sTfR | 1.8 to 4.6 mg/L |
Ranges depend heavily on the assay used, so always read your result against your laboratory's reference interval. Higher values suggest iron deficiency.
Results vary widely between assays, so values cannot be compared across labs. sTfR can also rise when red cell production is increased for other reasons, such as haemolysis. It is interpreted with the full iron picture.
Read alongside ferritin and transferrin saturation, and often used in the sTfR/log ferritin index to assess iron status.
One annual membership, 100+ biomarkers, every result explained in plain language with a personalized action plan and concierge guidance.
