The instrument used is a Beckman Coulter Unicel DXI 800. The Access Ferritin assay is a 2-site immunoenzymatic ("sandwich") assay. A sample is added to a reaction vessel with goat antiferritin-alkaline phosphatase conjugate, and paramagnetic particles coated with goat antimouse:mouse antiferritin complexes. Serum ferritin binds to the immobilized monoclonal antiferritin on the solid phase, while the goat antiferritin enzyme conjugate reacts with different antigenic sites on the ferritin molecules. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field, while unbound materials are washed away. Chemiluminescent substrate Lumi-Phos 530 is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is directly proportional to the concentration of ferritin in the sample. The amount of analyte in the sample is determined from a stored, multipoint calibration curve.(Package insert: Beckman Coulter Inc, Fullerton, CA 2009).