Transferrin

Some laboratories use 2.5 to 3.8 g/L; it rises in pregnancy and on oestrogen-containing medicines; use the range your lab printed.

Transferrin is the protein made by the liver that carries iron around the blood. When iron stores are low the liver makes more of it, and when stores are full it makes less. The test measures the amount of the carrier protein, not the iron on it.

Doctors request it as part of iron studies. It is used with the serum iron to calculate the transferrin saturation, and it helps to separate low iron (transferrin high) from the low iron level seen with inflammation (transferrin low or normal).

• Low iron stores
• Pregnancy
• Oestrogen-containing medicines, including the combined pill and HRT

• Inflammation or infection from any cause
• Liver disease, because less is made
• Poor nutrition or poor absorption of protein
• Nephrotic syndrome, where it is lost in the urine
• Iron overload
• Some cancers

• It rises in pregnancy and on oestrogen-containing medicines as an expected effect
• Any recent infection or inflammation lowers it
• Some laboratories report TIBC instead, which is transferrin expressed as the iron it could carry

No fasting needed for transferrin itself, though the paired serum iron is best taken fasting in the morning.

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