! Summary:The technical and diagnostic performance of fully automated immunoassays for free thyroxine and thyrotropin using streptavidin/biotui technology (Enzymun-Test®) were examined. The between-assay precision for ! free thyroxine was 10.4%, 5.4%, 2.5%, 2.3%, 1.1% and 1.8% at 3. 02, 6.27, 17.2, 21.9, 25.6, 42.7 pmol/I; and for | thyrotropin was 14.2%, 4.7%, 2.9%, 2.8%, 3.2%, 4.5% at 0.12, 0.46, 1.03, 2.05, 4.8, 12.7 mU/1. The functional 1 detection limit of the assay was 0.09 mU/1. Results for the free thyroxine method correlated well with the IMx (r =0.91) and the equilibrium dialysis (r = 0.95) assay. Results for the thyrotropin method correlated well with the Tandem®-TSH (r = 0.99) and the IMx (r = 0.99) assays. The euthyroid reference r nge was 11-23 pmol/1 and 0.5-3.9 mU/1 for free thyroxine and thyrotropin respectively. The free thyroxine assay was not influenced by changes in albumin or thyroxine binding globulin concentration but showed increases at oleic acid concentrations | > 4 mmol/1. Spuriously elevated free thyroxine concentration were found in 4 patients, due to assay interference i by antibodies in the serum. In a follow up study of 46 patients with non-thyroidal illness, serial measurements * showed fluctuating free thyroxine and thyrotropin concentrations with abnormal results occurring in 34%. In a hospital setting, a wider r nge pf free thyroxine (10-28 pmol/1) and thyrotropin (0.22-5.9 mU/1) concentration ι may be observed in patients who are clinically euthyroid. Abnormal thyroid function tests were however transient , and follow up resolved most diagnostic problems.

We have modified a commercially available procedure involving precast agarose gels (Paragon Isopal System) to measure alkaline phosphatase (EC 3.1.3.1) isoenzymes. Including wheat germ lectin in the equilibration buffer improved the resolution of the bone and liver isoenzymes. Unlike previously described wheat germ lectin affinity electrophoresis methods, the procedure measures bone, liver, and biliary isoenzymes in a single step. There was good correlation between the affinity electrophoresis and the neuraminidase preincubation methods for the measurement of bone (r = 0.958) and liver (r = 0.962) alkaline phosphatase isoenzymes. However, the affinity electrophoresis method also quantified minor isoenzyme fractions that were poorly resolved by the neuraminidase method. The method is technically simple, reproducible, and capable of rapid handling of large workloads.