Competitive Protein Binding Analysis for Thyroxine Using Sephadex Column (Tetralute) Evaluation of the Procedure, Interference with Drugs and Clinical Application

The method of competitive protein binding analysis of T4 using Tetralute kit was evaluated. The net retention was decreased when the procedure of competition and separation was performed under higher temperature but the final T4-I values were constant when the standard and test sera were identically...

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Published inRADIOISOTOPES Vol. 24; no. 11; pp. 763 - 768
Main Authors KATAYAMA, Yoshiaki, SAWAZAKI, Norio, KUMAHARA, Yuichi, KAWASHIMA, Minoru, MIYAI, Kiyoshi, ISHIBASHI, Kaichiro, AZUKIZAWA, Mizuo
Format Journal Article
LanguageJapanese
Published Japan Radioisotope Association 15.11.1975
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ISSN0033-8303
1884-4111
DOI10.3769/radioisotopes.24.11_763

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Summary:The method of competitive protein binding analysis of T4 using Tetralute kit was evaluated. The net retention was decreased when the procedure of competition and separation was performed under higher temperature but the final T4-I values were constant when the standard and test sera were identically treated. Coefficient of variation (C.V.) was 4% (within-assay) and 6% (between-assay) respectively. However, the T4-I values of pooled serum for quality control were slightly lower in earlier experiments in which correction factors (1.03-1.62 in 18 out of 21 assays) were necessary. T4-I values were determined by the Tetralute in 155 cases. These were as follows : 4.9±0.8 μg/dl (euthyroid subjects), 6.4±1.2 μg/dl (cord serum), 7.1±1.1 μg/dl (pregnant women), 9.0±3.6 μg/dl (trophoblastic disease), 13.3±4.8 μg/dl (Graves' disease), 6.3±1.6 μg/dl (Plummer's disease), <2.5-3 μg/dl (primary hypothyroidism), <2.5 μg/dl (TBG deficiency), 5.5±1.8 μg/dl (hypopituitarism), 5.2±1.4 μg/dl (Pituitary adenoma) and 3.6±0.7 μg/dl (anorexia nervosa) . There was good correlation between T4-I values determined by Tetralute and Res-O-Mat T4 (r=0.96) . Following oral administration of Telepaque serum PBI was markedly elevated while T4-I determined by Tetralute did not change. In vitro addition of diphenylhydantoin (500 μg/ml), salicylate (4 mg/ml) and phenobarbital (1 mg/ml) had no or little effects on T4 deter-mination by Tetralute. Benzbromarone in high concentration (0.1 mg/ml) caused higher value of T4-I determined by Tetralute when added to TBG solution but only slightly increase when added to serum.
ISSN:0033-8303
1884-4111
DOI:10.3769/radioisotopes.24.11_763