Studies on the Accuracy of a Quantitative Kit Radioimmunoassay for Free Thyroxine

Abstract

SUMMARY Experiments designed to determine the accuracy of the Corning Immophase Free T 4 assay revealed that there was a marked perturbation of thyroxine binding to the serum proteins during the assay; binding of 125 1_T 4 to the immobilised T 4 antibody in the absence of merthiolate increased considerably with buffer dilution of serum; and the free thyroxine concentration declined significantly during pregnancy. These changes in measured fT 4 were not observed with an equilibrium dialysis-radioimmunoassay procedure. The assay was precise, easily performed, and as effective as the free thyroxine index (FTI) in diagnosing thyroid disease. We conclude that the assay does not provide an accurate quantitative estimation of serum IT4 concentration in samples with elevated TBG concentration and that the kinetic principles on which the assay is based are altered as serum binding-protein concentration is reduced (serum dilution). Both FTI and fT 4 (Corning) data in pregnant patients should be interpreted with caution and with reference to clinical symptomatology and other thyroid function tests.

Serum thyrotrophin concentration measured by sensitive assays in normal pregnancy

“…The concentration of free thyroid hormones is reported to decrease (Giles 1982), increase (Wang et al 1985) or remain unchanged (Symons et al 1983) during pregnancy. Similarly basal thyrotrophin (TSH) has bcen reported to increase (Weeke et al 1982;Pacchiarotti et al 1986), decrease (Yamamoto et al 1979;Harada et al 1979) or remain normal (McLellan et al 1987) in pregnancy.…”

New horizons in the roles and associations of COX-2 and novel natural inhibitors in cardiovascular diseases

“…COX-2 includes cyclooxygenase (COX) and peroxidase (POX) active sites (Chan et al 2019 ; Chandel et al 2018 ). AA binds to the COX active site and is converted to PGG 2 .…”