Thumbnail
Access Restriction
Open

Author Cuaron, A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword RADIOLOGY AND NUCLEAR MEDICINE ♦ IMMUNOGLOBULINS ♦ CONFIGURATION INTERACTION ♦ THYROXINE ♦ ELECTROPHORESIS ♦ RADIOIMMUNOASSAY ♦ BIOCHEMISTRY ♦ PATIENTS ♦ THYROID ♦ AMINO ACIDS ♦ BODY ♦ CARBOXYLIC ACIDS ♦ CHEMISTRY ♦ ENDOCRINE GLANDS ♦ GLANDS ♦ GLOBULINS ♦ HORMONES ♦ IMMUNOASSAY ♦ IMMUNOLOGY ♦ ISOTOPE APPLICATIONS ♦ ORGANIC ACIDS ♦ ORGANIC COMPOUNDS ♦ ORGANIC HALOGEN COMPOUNDS ♦ ORGANIC IODINE COMPOUNDS ♦ ORGANS ♦ PEPTIDE HORMONES ♦ PROTEINS ♦ RADIOASSAY ♦ RADIOIMMUNOLOGY ♦ THYROID HORMONES ♦ TRACER TECHNIQUES 550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
Abstract The physico-chemical interactions between thyroxine (T/sub 4/) and thyroxine-binding globulin (TBG) of low binding capacity were investigated by radioimmunoassay, equilibrium dialysis, and reverse flow electrophoresis. Knowledge of total and free T/sub 4/ (FT/sub 4/) concentrations in serum, and of the total binding capacity of the protein carrier (TTBG), allowed the determination of the association constant ruling these interactions (K/sub tbg/). Correlation between T/sub 4/ and FT/sub 4/ varies with TTBG, shifting the normal range for T/sub 4/. The level of FT/sub 4/ in serum is a function of the fractional saturation of TBG by endogenous hormones, which depends on T/sub 4/ and TTBG. Data on T/sub 4/, TTBG, and K/sub tbg/ were integrated into the general equation of the law of mass action and the results showed a very significant linear correlation with the values of FT/sub 4/ measured by equilibrium dialysis. It is concluded that the misleading results of serum T/sub 4/ measurements and of the free T/sub 4/ index, obtained in euthyroid individuals with low TTBG, cannot be ascribed to a reduction of the intrinsic sensitivity of the assay due to oversaturation of TBG by endogenous T/sub 4/, as previously postulated by others, but to a shift of their normal ranges produced by abnormal variations of TTBG. These results stress the need for data regarding TTBG for the proper interpretation of T/sub 4/, and for the calculation of the fractional saturation of TBG and the FT/sub 4/ concentration in serum. The authors have solved this problem by using an empirical equation relating TTBG to T/sub 4/ and triiodothyronine (T/sub 3/) uptake, which was previously derived by other workers.
Educational Use Research
Learning Resource Type Article
Publisher Date 1987-09-01
Publisher Place United States
Journal J. Nucl. Med. Technol.
Volume Number 15
Issue Number 3
Organization National Institute of Cardiology, Mexico City, MX


Open content in new tab

   Open content in new tab