Effect of total binding capacity of thyroxine binding globulin on the free thyroxine index
Journal Article
·
· J. Nucl. Med. Technol.; (United States)
OSTI ID:5875749
In search of a definite source of misleading free thyroxine index (FT/sub 4/I), the relationship between in vitro thyroid testing results and thyroxine-binding globulin (TBG) capacities were reexamined in sera from a population with a relatively high prevalence of serum TBG alterations. Sera from 21 subjects with different total thyroxine-binding globulin capacities (TTBG), were loaded with graded amounts of thyroxine (T/sub 4/) and assayed for T/sub 4/, T/sub 3/ uptake (T/sub 3/U), TTBG, and free T/sub 4/ concentration (FT/sub 4/I). Serum T/sub 4/, T/sub 3/U, and the calculated FT/sub 4/ index (FT/sub 4/I) were able to separate efficiently the samples according to their FT/sub 4/, but their respective normal ranges varied with TTBG. Interpretation of the results of the in vitro tests, in the light of TTBG, greatly improved their operating characteristics in the study of 141 patients with a high prevalence of TBG alterations. The misleading FT/sub 4/I is not the outcome of reduced intrinsic sensitivities of the in vitro tests, but a consequence of a shift of their normal ranges caused by a change of TTBG. By estimating TTBG from the values of T/sub 4/ and T/sub 3/U, this problem is easily solved without adding cost.
- Research Organization:
- Instituto Nacional de Cardiologia Ignacio Chavez, Mexico City, Mexico
- OSTI ID:
- 5875749
- Journal Information:
- J. Nucl. Med. Technol.; (United States), Journal Name: J. Nucl. Med. Technol.; (United States) Vol. 14:2; ISSN JNMTB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
BIOLOGICAL FUNCTIONS
BLOOD SERUM
BODY
CARBOXYLIC ACIDS
CHROMATOGRAPHY
ENDOCRINE GLANDS
FUNCTIONS
GLANDS
HORMONES
IMMUNOASSAY
IMMUNOLOGY
IN VITRO
ISOTOPE APPLICATIONS
LIQUID COLUMN CHROMATOGRAPHY
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PATIENTS
PEPTIDE HORMONES
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
SENSITIVITY
SEPARATION PROCESSES
THYROID
THYROID HORMONES
THYROXINE
TRACER TECHNIQUES
TRIIODOTHYRONINE
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
BIOLOGICAL FUNCTIONS
BLOOD SERUM
BODY
CARBOXYLIC ACIDS
CHROMATOGRAPHY
ENDOCRINE GLANDS
FUNCTIONS
GLANDS
HORMONES
IMMUNOASSAY
IMMUNOLOGY
IN VITRO
ISOTOPE APPLICATIONS
LIQUID COLUMN CHROMATOGRAPHY
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PATIENTS
PEPTIDE HORMONES
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
SENSITIVITY
SEPARATION PROCESSES
THYROID
THYROID HORMONES
THYROXINE
TRACER TECHNIQUES
TRIIODOTHYRONINE