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In vitro thyroid testing in populations with low thyroxine binding globulin capacity

Abstract

Total thyroxine (T{sub 4}) concentration in serum is a reliable indicator of thyroid function in most individuals, but it is affected by altered concentrations of thyroxine-binding globulin (TBG) in serum. Within certain limits, the variations in total TBG binding capacity (TBG{sub TOTAL}) caused by the fluctuations in the concentration of this binding globulin in serum can be modulated by calculating the free thyroxine index (FT{sub 4}I) as the product of T{sub 4} and the in vitro uptake of triiodothyronine by a secondary binder (T{sub 3}U). This calculation is empirically based on the facts that free TBG binding capacity (TBG{sub FREE}) is inversely related to T{sub 3}U and that T{sub 4} and T{sub 3}U show opposite behaviour when measured in sera with altered TBG: a low T{sub 4} in serum with reduced TBG{sub TOTAL} is compensated by a high value for T{sub 3}U, while an elevated T{sub 4} in serum with increased TBG{sub TOTAL} is compensated by a low value for T{sub 3}U. In both cases the product of T{sub 4} and T{sub 3} renders a normal FT{sub 4}I value, showing a certain association with the concentration of free T{sub 4} in serum (FT{sub 4}). In fact, this index has been  More>>
Authors:
Publication Date:
Dec 31, 1992
Product Type:
Technical Report
Report Number:
NMS-1
Reference Number:
SCA: 550601; PA: AIX-29:049612; EDB-98:095822; SN: 98002003648
Resource Relation:
Other Information: DN: 3 figs, 4 tabs; PBD: 1992; Related Information: Is Part Of Handbook of nuclear medicine practice in developing countries; PB: 728 p.
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; BLOOD SERUM; CONCENTRATION RATIO; DEVELOPING COUNTRIES; DIAGNOSTIC TECHNIQUES; GLOBULINS; IN VITRO; PATIENTS; THYROID; THYROXINE
OSTI ID:
640600
Research Organizations:
International Atomic Energy Agency, Vienna (Austria). Nuclear Medicine Section
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ON: DE98635463; TRN: XA9847614049612
Availability:
INIS; OSTI as DE98635463
Submitting Site:
INIS
Size:
pp. 261-272
Announcement Date:
Sep 18, 1998

Citation Formats

Cuaron, A. In vitro thyroid testing in populations with low thyroxine binding globulin capacity. IAEA: N. p., 1992. Web.
Cuaron, A. In vitro thyroid testing in populations with low thyroxine binding globulin capacity. IAEA.
Cuaron, A. 1992. "In vitro thyroid testing in populations with low thyroxine binding globulin capacity." IAEA.
@misc{etde_640600,
title = {In vitro thyroid testing in populations with low thyroxine binding globulin capacity}
author = {Cuaron, A}
abstractNote = {Total thyroxine (T{sub 4}) concentration in serum is a reliable indicator of thyroid function in most individuals, but it is affected by altered concentrations of thyroxine-binding globulin (TBG) in serum. Within certain limits, the variations in total TBG binding capacity (TBG{sub TOTAL}) caused by the fluctuations in the concentration of this binding globulin in serum can be modulated by calculating the free thyroxine index (FT{sub 4}I) as the product of T{sub 4} and the in vitro uptake of triiodothyronine by a secondary binder (T{sub 3}U). This calculation is empirically based on the facts that free TBG binding capacity (TBG{sub FREE}) is inversely related to T{sub 3}U and that T{sub 4} and T{sub 3}U show opposite behaviour when measured in sera with altered TBG: a low T{sub 4} in serum with reduced TBG{sub TOTAL} is compensated by a high value for T{sub 3}U, while an elevated T{sub 4} in serum with increased TBG{sub TOTAL} is compensated by a low value for T{sub 3}U. In both cases the product of T{sub 4} and T{sub 3} renders a normal FT{sub 4}I value, showing a certain association with the concentration of free T{sub 4} in serum (FT{sub 4}). In fact, this index has been shown to be superior than several FT{sub 4} assay systems in the assessment of thyroid status in clinical euthyroid subjects with relatively high or low T{sub 3}U 3 figs, 4 tabs}
place = {IAEA}
year = {1992}
month = {Dec}
}