title: Evaluation of a new homogeneous enzyme inhibitor immunoassay of serum thyroxine with use of a bichromatic analyzer.
abstract: We evaluated a new homogeneous enzyme immunoassay of thyroxine with use of a discrete analyzer (the ABA-100 Bichromatic Analyzer), modified with an auxiliary dispenser assembly. The assay is based on inhibition of hydrolysis of the substrate, acetyl-beta-(methylthio)choline iodide, by acetylcholinesterase (acetylcholine hydrolase; EC 3.1.1.7). Thyroxine covalently linked to a cholinesterase inhibitor irreversibly inhibits acetylcholinesterase, but if this thyroxine conjugate is bound to antibody it is not inhibitory. Seventy-five patients' samples may be analyzed in 1 h of instrument time. Precision and accuracy are excellent, results correlate well with those by radioimmunoassay, and there were no instances of confused clinical interpretation resulting from use of the proposed assay.
mesh_terms: D001322:Autoanalysis / Q000379:methods; D002800:Cholinesterase Inhibitors; D005260:Female; D006801:Humans; D006868:Hydrolysis; D007124:Immunoenzyme Techniques; D008297:Male; D011247:Pregnancy; D011863:Radioimmunoassay; D013860:Thiocholine / Q000031:analogs & derivatives; D013974:Thyroxine / Q000097:blood*
chemical_list: D002800:Cholinesterase Inhibitors; D013860:Thiocholine; C027395:acetyl-beta-(methylthio)choline; D013974:Thyroxine