Enzyme-labeled immunosorbent assay for serum ferritin: method evaluation and comparison with two radioassays

We report our evaluation of a commercially available procedure and reagents for determination of ferritin in serum by enzyme-labeled immunosorbent assay (ELISA). Results by our procedure and the "Fer Iron" (Ramco Labs) procedure shows a degree of association (r) of 0.95 and a regression equation of y = 1.03x - 33. Similarly, our procedure compared to the "Gamma Dab" (Clinical Assays) ferritin procedure shows a degree of association of 0.98 and a regression equation of y = 0.93x - 11. Between-day standard deviations were 6 and 22 micrograms/L (n = 24 and 20) for ferritin concentrations of 20 and 300 micrograms/L, respectively. Ferritin values showed no correlation with total iron concentration, but show a broad inverse relationship with iron-binding capacities. The favorable correlation with existing procedures and the speed of the analysis commend the use of ELISA for measurement of ferritin in serum.