Quantitation of serum ferritin by enzyme-linked immunosorbent assay (ELISA)

We have developed an enzyme-linked immunosorbent assay (ELISA) for determining ferritin in serum. In this assay the solid phase consists of rabbit antiferritin IgG adsorbed onto PVC microtitre plates. Ferritin from standards or samples binds to the solid phase and is then detected by a conjugate consisting of rabbit antiferritin-IgG and horseradish peroxidase. The entire assay can be performed in 5 hours, with good precision. The assay has a useful range of 1 to 64 microgram/l and serum samples therefore have to be diluted 10-fold. The coefficient of variation for 6 samples (1,5-40,1 microgram/l) assayed 12 times on the same plate varied from 4% to 9% (intra-assay). When these 6 samples were assayed on different plates and on different days by two technicians the coefficients of variation varied from 4% to 11% (inter-assay). The lowest detectable level of ferritin was 1 microgram/l. Forty-six serum samples from blood donors were assayed by the method described here (gamma) and compared with results obtained by RIA (alpha). The resulting regression equation was gamma = 1,073 alpha -- 4,33; r = 0,984.