Semiautomated homogeneous enzyme immunoassay of total serum thyroxine with a kinetic analyzer

A new semiautomatic procedure for determination of total serum thyroxine was adapted to a kinetic analyzer, LKB 2086 Mark II. The ABA thyroxine assay kit was used, and although the assay procedure was modified, the advantage of small reagent volumes, short measuring times, and automation were retained. The results were analyzed off-line with a programmable desk-top calculator. The method has a precision of 7% (CV) and a sensitivity of 8 nmol/L. Values in sera from 64 patients analyzed by enzyme immunoassay and by radioimmunoassay correlated well (r = 0.975). One kit contains enough reagents for 500 assays, and an operator could do 25 samples (i.e., 64 assays) in about 4 h.