A solid phase radioimmunoassay method for ferritin in serum using (125)I-labelled ferritin

A solid phase radioimmunoassay method for ferritin in serum was developed using ferritin conjugated with an (125)I-labelled ester. The method was based upon competitive inhibition utilizing the free antigen-binding sites of antibodies to ferritin bound to a ferritin which had been chemically coupled to insoluble polysaccharide particles. The method was evaluated with regard to specificity, sensitivity, precision and practicability and was found to be a robust method suitable for the assay of ferritin in human serum in clinical studies. There was a significant (P<0.001) difference between the ferritin levels in healthy men and women, mean values 100 and 66 arb U/l respectively. Male blood donors had significantly (P<0.002) lower ferritin levels in serum (mean 68.5 arb U/l) than other healthy men. Patients with iron overload or hepatic damage had high values, as expected, and the serum levels of ferritin reflected changes in iron deposits during phlebotomy and iron treatment in 3 healthy men.