Soluble transferrin receptor

The range depends strongly on the laboratory method (some print 0.8 to 1.8 or 2.2 to 5.0 mg/L) and results are not comparable between methods; use the range your lab printed.

Cells that need iron put transferrin receptors on their surface to catch it, and a fragment of these receptors circulates in the blood. When the body's cells are short of iron they make more receptors, so the soluble transferrin receptor rises. Unlike ferritin, it is not pushed up by inflammation, which is its main advantage.

Doctors request it when ferritin cannot be relied on because of inflammation, liver disease or long-term illness, to help decide whether iron is genuinely short. It is a specialist test that is not part of routine iron studies.

• Low iron in the tissues
• Conditions where the bone marrow is making red cells quickly, such as red cell breakdown or thalassaemia
• Recent blood loss
• Living at altitude
• Erythropoietin injections

• Conditions where the bone marrow is making few red cells, such as after chemotherapy or in some marrow conditions
• Long-term kidney disease
• Iron overload

• Different laboratory methods give very different numbers, so results from two laboratories cannot be compared
• It is higher in people of African ancestry in the general population
• It rises during recovery from any anaemia as the marrow speeds up

No fasting needed. Read together with ferritin and CRP. Some laboratories also report the ratio of sTfR to log ferritin.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.