Methotrexate-labeled iodothyronine conjugates and method, reagent means and test device for the determination of iodothyronine in or iodothyronine uptake of a liquid sample

摘要

Methotrexate-labeled iodothyronine conjugates useful as labeled conjugates in specific binding assays (e.g., homogeneous immunoassays) for determining iodothyronines, particularly thyroxine and triiodothyronine, or for determining iodothyronine uptake in liquid samples. The methotrexate label is monitored preferably by measuring its inhibitory effect on the enzyme dihydrofolate reductase. Also provided are assay methods, reagent means, test kits and test devices for determining an iodothyronine, comprising the methotrexate-labeled conjugate, a binding protein (e.g., antibody) for the iodothyronine, dihydrofolate reductase, and an indicator of dihydrofolate reductase activity, and for determining iodothyronine uptake, comprising the labeled conjugate, binding protein, dihydrofolate reductase, and enzyme indicator.