Five kits for estimating free thyroxin concentration in serum evaluated, and correlated with other indices to thyroid status.

Wilke, T J

doi:10.1093/clinchem/28.10.2051

Cited by 23 publications

(4 citation statements)

References 14 publications

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“…Modifications of free hormone levels during pregnancy have been the subject of controversies over the past years, partially biased by methodological flaws in the techniques used for determining free hormones, which were affected by the changes in TBG, albumin, and FFA associated with pregnancy (40)(41)(42)(43). Several reports in-…”

Section: Discussionmentioning

confidence: 99%

Regulation of Maternal Thyroid during Pregnancy*

Glinoer

Nayer²,

Bourdoux³

et al. 1990

The Journal of Clinical Endocrinology & Metabolism

661

379

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A prospective study was undertaken in 606 healthy women during pregnancy to evaluate the changes occurring in maternal thyroid economy as a result of 1) the increased thyroid hormone-binding capacity of serum, 2) the effects of increased levels of hCG on TSH and on the thyroid, and 3) a marginally low iodine intake in the population (50-75 micrograms/day). Four main features were observed. First, thyroidal activity adjusted to the marked increase in serum T4-binding globulin: pregnancy was accompanied by an overall reduction in the T4/T4-binding globulin ratio, with lower free T4 and T3 levels, although in most cases free hormone levels remained within the normal range. The adjustment of thyroidal output of T4 and T3 did not occur similarly in all subjects. In approximately one third of the women, there was relative hypothyroxinemia, higher T3/T4 ratios (presumably indicating preferential T3 secretion), and higher, although normal, serum TSH concentrations. Second, high hCG levels were associated with thyroid stimulation, both functionally (lower serum TSH) and anatomically (increased thyroid size). The data are consistent with a TSH-like effect of hCG on the thyroid. Hence, regulation of the maternal thyroid is complex, resulting from both elevated hCG (mainly in the first half of gestation) and increasing TSH (mainly in the second half of gestation). Third, a significant increase in serum thyroglobulin levels was observed throughout gestation, especially during the last trimester. Fourth, increased thyroid volume was common, and goiter formation not uncommon (goiter was found in 9% of women at delivery). In conclusion, the alterations in maternal thyroid function during gestation are intricate and far from fully understood. In areas of marginally low iodine intake, gestation is associated in a significant number of women with relative hypothyroxinemia, increased thyroglobulin, and enlarged thyroid.

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Section: Discussionmentioning

confidence: 99%

Regulation of Maternal Thyroid during Pregnancy*

Glinoer

Nayer²,

Bourdoux³

et al. 1990

The Journal of Clinical Endocrinology & Metabolism

661

379

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“…The concentration of TBG progressively increases with the duration of pregnancy (18,19). Therefore -äs expected -T 4 values by both methods were significantly increased (p < 0.001) äs compared with the control group in third trimester pregnants.…”

Section: Subjects With Increased Thyroid Hormone Binding Capacitymentioning

confidence: 99%

Laboratory and Clinical Experience with a Monoclonal Antibody-Based Radioimmunoassay for Serum Total Thyroxine

Wilke¹,

Sheedy²,

Hirning³

1985

Clinical Chemistry and Laboratory Medicine

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The performance characteristics and diagnostic value of a monoclonal antibody-based radioimmunoassay for serum total thyroxine (Mallinckrodt) are described. Between-batch precision (coefficient of Variation) was 10.4% at 87 nmol/1 and 3.3% at 185 nmolA Scatchard analysis revealed a linear plot with a K a of 5.4 x 10 8 1/mol. \ Sensitivity was 4.5 nmol/1 of thyroxine. An association study showed that the assay reached equilibrium well within the specified incubation time. Cross-reaction of triiodothyronine and reverse triiodothyronine in the assay was 0.6% and 25.0% respectively. Analytical recovery was 91-110%. Linearity was well demonstrated but dilutions of a high concentration of thyroxine in serum did not parallel the Standard curve. The correlation coefficient for comparison with a polyclonal antibody assay was 0.95 for 83 patients. The diagnostic accuracy of the monoclonal antibody assay was adequate for most patients with thyroid disease, pregnant women, oral contraceptive users and subjects on thyroxine-replacement therapy. Measurement of total thyroxine by a monoclonal antibody-based method shows no definite advantage over the conventional polyclonal antibody assay. Erfahrungen in Laboratorium undKlinik mit einem Radioimmunassay für das gesamte Thyroxin im Serum auf der Grundlage eines monoklonalen Antikörpers Zusammenfassung: Die Charäkteristika der Durchführung und der diagnostische Wert eines Radioimmunassay mit monoklonalem Antikörper für das gesamte Thyroxin im Serum (Mallinckrodt) werden beschrieben. Die Impräzision von Serie zu Serie beträgt als Variationskoeffizient 10,4% bei 87 nmol/1 und 3,3% bei 185 nmol/1. Die Scatchard-Analyse ergab einen linearen Verlauf mit einem Wert für K a von 5,4 x 10 8 1/mol. Die Empfindlichkeit betrug 4,5 nmol/1 Thyroxin. Eine Bindungsstudie ergab, daß das Gleichgewicht innerhalb der angegebenen Inkubationszeit völlig erreicht wird. Die Kreuzreaktionen von Triiodthyronin und reverse Triiodthyronin betrugen 0,6 bzw. 25,0%. Die analytische Wiederfindung betrug 91-110%. Es konnte völlige Linearität nachgewiesen werden, jedoch ergaben Verdünnungen einer hohen Konzentration von Thyroxin im Serum keinen parallelen -Verlauf mit der Standardkurve. Der Korrelationskoeffizient für ein Vergleichsverfahren mit polykloiiälem Antikörper betrug r = 0,95 (n = 83 Patienten). Die diagnostische Richtigkeit des Radioimmunassay mit monoklonalem Antikörper war für die meisten Patienten mit Schilddrüsenerkrankungen, für Frauen* die orale Kontraceptiva einnahmen oder schwanger waren, sowie Personen unter Thyroxin^Substitution genügend. Die Bestimmung des Gesamtthyroxins unter Verwendung eines monoklonalen Antikörpers zeigt keinen deutlichen Vorteil gegenüber der Verwendung konventioneller polyklonaler Antikörper.

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“…Various methods have been employed to the determination of FT4 in serum, such as equilibrium dialysis 3 - 7 , ultrafiltration 8 , chromatography on polyacrylamide gel 9 , 10 or Sephadex 11 , radioimmunoassay (RIA) by use of the radioactive isotope 125 I 12 - 14 , enzyme immunoassay 15 - 17 , time-resolved fluorescence 18 , bioluminescent immunoassay 19 , fluoroimmunoassay 20 - 23 , ,chemiluminescence immunoassay 24 , 25 , electrochemiluminescence immunoassay 26 , 27 , and mass spectrometry 28 , 29 . These methods have disadvantages.…”

Section: Introductionmentioning

confidence: 99%

Development of a highly sensitive and selective microplate chemiluminescence enzyme immunoassay for the determination of free thyroxine in human serum

Wang¹,

Chen²,

Lin³

et al. 2007

Int. J. Biol. Sci.

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A microplate chemiluminescence enzyme immunoassay (CLEIA) with high sensitivity, selectivity and reproducibility was developed for the determination of free thyroxine (FT4) in human serum. A competitive assay has been utilized with horseradish peroxidase (HRP) labeled thyroxine analog in the chemiluminescence (CL) detection. The CL signal produced by the emission of photons from luminol was directly proportional to the amount of analyte. The linear range was 0.45-7.5 ng dL -1 and the detection limit was 0.09 ng dL -1 . Experimental conditions, such as temperature, pH, incubation time, titration level and other relevant variables upon the CL signal have been examined and optimized. A coefficient of variance of less than 16% was obtained for intra-and inter-assay precision. The present method has been successfully applied to the analysis of FT4 in human serum. The positive and negative coincidence ratios are satisfactory. Good correlations were obtained between the results by the proposed method and radioimmunoassay (RIA), as well as a Bayer ACS-180SE detection system.

show abstract

Five kits for estimating free thyroxin concentration in serum evaluated, and correlated with other indices to thyroid status.

Cited by 23 publications

References 14 publications

Regulation of Maternal Thyroid during Pregnancy*

Regulation of Maternal Thyroid during Pregnancy*

Laboratory and Clinical Experience with a Monoclonal Antibody-Based Radioimmunoassay for Serum Total Thyroxine

Development of a highly sensitive and selective microplate chemiluminescence enzyme immunoassay for the determination of free thyroxine in human serum

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