Serum ferritin concentration and isoferrtin patterns detected by immunoradiometric assay

Two-site immunoradiometric assay for serum ferritin was developed by anti-human liver ferritin antiserum applied on polyvinyl V-bottom microtiter plates. The coefficient of variation was 4.4-5.9% of liver ferritin dissolved in 1/4 diluted human serum at a concentration of 0.625-125 ng/ml. The lowest concentration (0.625 ng/ml) was statistically distinguishable from the background by Student's t test (p < 0.05). Isoferritin patterns of serum ferritin and tissue ferritins were examined by the combination of gel isoelectric focussing and 2-site immunoradiometric assay in order to explore any similarities in pIs within these ferritins. Although serum ferritin had wide range of pIs, its basic isomers corresponded well to those of liver and spleen ferritin. Geometric means and their 95% confidence limits in serum ferritin concentration were 70 ng/ml and 12-411 ng/ml, respectively, in sera of 205 healthy males (16-25 years), and 12 ng/ml and 1-211 ng/ml, respectively, in 421 healthy females (16-59 years).