Evaluation of a radiometric method for determination of total and unsaturated iron-binding capacities and serum iron

We describe an evaluation of the "RES-OMAT FE-59" radiometric kit (Mallinckrodt Australia Pty. Ltd.) for determination of total iron-binding capacity and unsaturated iron-binding capacity; serum iron may be calculated from total iron-binding capacity and unsaturated iron-binding capacity. Values obtained on patients' sera were compared with those obtained by continuous-flow analysis; correlation coefficients were 0.92, 0.93, and 0.88 for total iron-binding capacity, unsaturated iron-binding capacity, and iron, respectively. Precision between-run and within-run was almost identical and compares very favorably with that reported by Dixon [Ann. Clin. Biochem. 10, 127 (1973)] and that achieved in inter-laboratory surveys. Analytical recovery averaged only 83.5%, but results of analyses of sera with assigned or consensus values showed good accuracy. Satisfactory performance cannot be achieved with lyophilzed bovine quality-control materials. The kit has significant technical advantages over colorimetric methods and good short- and long-term analytical performance.