Transferrin is a protein with a molecular weight of approximately 79.6 kDa. It is the main protein of iron transport (III). It is synthesised mostly in the liver, but also in the choroid plexus of the brain. The transferrin plasma concentration is regulated by the availability of iron in the body: during iron deficiency, the transferrin plasma concentration increases, and returns to normal when the deficiency is treated.
A large transferrin plasma concentration may be caused by microcytic hypochromic anaemia (the assay of transferrin may then be used for treatment monitoring), during iron deficiency, but also during pregnancy or even during oestrogen treatment.
A decrease of transferrin can be measured in the case of the acute inflammatory phase, chronic hepatitis or even malnutrition. A nephrotic syndrome can also decrease the transferrin concentration in plasma.