Two new two-step immunoassays for free thyroxin evaluated: solid-phase radioimmunoassay and time-resolved fluoroimmunoassay

1990 ◽  
Vol 36 (7) ◽  
pp. 1355-1360 ◽  
Author(s):  
P Nuutila ◽  
P Koskinen ◽  
K Irjala ◽  
L Linko ◽  
H L Kaihola ◽  
...  
Keyword(s):  
Solid Phase ◽  
Equilibrium Dialysis ◽  
Late Pregnancy ◽  
Clinical State ◽  
Albumin Concentration ◽  
Time Resolved ◽  
One Step ◽  
Solid Phase Radioimmunoassay ◽  
Dialysis Method ◽  
Method R

Abstract We measured concentrations of free thyroxin (FT4) in serum by using two new two-step FT4 assays--a solid-phase two-step radioimmunoassay. Spectria, and a time-resolved fluoroimmunoassay. Delfia--and compared the results with those by a two-step FT4 assay (RIA-gnost), a one-step FT4 analog assay (Amerlex-M), and FT4 measured after equilibrium dialysis. The new FT4 assays classified 30 hypothyroid and 43 hyperthyroid patients (untreated) well. In 138 patients with nonthyroidal illness (NTI) and in late pregnancy (n = 36), fewer subnormal FT4 values were reported by Spectria (P less than 0.001), Delfia (P less than 0.001), and RIA-gnost (P less than 0.01) than by Amerlex-M. The results of the Spectria and Delfia methods correlated with the results of the dialysis method (r = 0.76) in NTI patients and pregnancy, and were in better agreement with the clinical state than was FT4 by Amerlex-M. The FT4 values by Amerlex-M, but not by other methods, correlated with albumin concentration. We conclude that these new two-step methods present good alternatives for FT4 analysis.

scholarly journals A solid-phase radioimmunoassay for free thyroxine in serum compared with equilibrium dialysis method.

1980 ◽  
Vol 132 (4) ◽  
pp. 375-383
Author(s):  
KATSUMI YOSHIDA ◽  
TOSHIRO SAKURADA ◽  
HIROFUMI KITAOKA ◽  
HIROSHI FUKAZAWA ◽  
NOBUKO KAISE ◽  
...  
Keyword(s):  
Solid Phase ◽  
Equilibrium Dialysis ◽  
Free Thyroxine ◽  
Solid Phase Radioimmunoassay ◽  
Dialysis Method

Laser-excited immunofluorometric assay of prolactin, with use of antibodies coupled to lanthanide-labeled diethylenetriaminepentaacetic acid.

1986 ◽  
Vol 32 (7) ◽  
pp. 1323-1327 ◽  
Author(s):  
H Déchaud ◽  
R Bador ◽  
F Claustrat ◽  
C Desuzinges
Keyword(s):  
Plasma Sample ◽  
Solid Phase ◽  
Nitrogen Laser ◽  
Diethylenetriaminepentaacetic Acid ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Step Procedure ◽  
Polystyrene Tube ◽  
Sandwich Type ◽  
One Step

Abstract We describe an immunofluorometric assay for prolactin based on lanthanide labeling of a monoclonal antibody and measuring time-resolved fluorescence. In this "sandwich"-type assay, the label (Eu3+) was bound to the second antibody by means of a simple, rapid method involving the anhydride of diethylenetriaminepentaacetic acid. To measure the photoluminescence of europium (or other lanthanides), we have developed a time-resolved fluorometer with a nitrogen laser as the pulsed excitation source. During the assay, the solid-phase antibody immobilized inside a polystyrene tube is incubated with the plasma sample and the second antibody in a one-step procedure. Results for 67 human plasmas correlated well (r = 0.98) with those by an immunoradiometric method.

Europium and samarium as labels in time-resolved immunofluorometric assay of follitropin.

1987 ◽  
Vol 33 (1) ◽  
pp. 48-51 ◽  
Author(s):  
R Bador ◽  
H Déchaud ◽  
F Claustrat ◽  
C Desuzinges
Keyword(s):  
Solid Phase ◽  
Lanthanide Ions ◽  
Nitrogen Laser ◽  
Plasma Samples ◽  
Diethylenetriaminepentaacetic Acid ◽  
Time Resolved ◽  
Step Procedure ◽  
One Step ◽  
The Difference ◽  
Incorporation Ratio

Abstract This time-resolved immunofluorometric assay for human follitropin involves use of europium- or samarium-labeled monoclonal antibodies, with an average incorporation ratio of 3 mol of Eu3+ or Sm3+ per mole of antibody. These lanthanide ions are bound to the antibody molecules by means of the anhydride of diethylenetriaminepentaacetic acid. The solid-phase antibody is immobilized inside polystyrene tubes in which plasma samples were assayed in a one-step procedure. After incubation, the fluorescence intensity of Eu3+ or Sm3+ label is measured by time-resolved fluorometry, with a nitrogen laser as the pulsed excitation source. The sensitivity of the assay is largely better with Eu3+ than with Sm3+ because of the difference in their intrinsic luminescence properties. Results obtained with the proposed methods correlated well with those by an immunoradiometric method.

On the albumin dependence of measurements of free thyroxin. I. Technical performance of seven methods.

1986 ◽  
Vol 32 (1) ◽  
pp. 108-115 ◽  
Author(s):  
G Csako ◽  
M H Zweig ◽  
C Benson ◽  
M Ruddel
Keyword(s):  
Equilibrium Dialysis ◽  
Inverse Correlation ◽  
Albumin Concentration ◽  
Good Precision ◽  
Step Method ◽  
Significant Inverse Correlation ◽  
Technical Performance ◽  
One Step ◽  
The One ◽  
Marked Dependence

Abstract We evaluated three one-step (analog) and two two-step radioimmunoassay for free thyroxin (FT4), and a FT4 index calculated from the total T4 (TT4) and thyroxin-binding globulin (TBG) ratio for technical performance, for correlation with the reference FT4 method (equilibrium dialysis), and for dependence on TBG and albumin concentrations. The one-step methods (Amerlex, Coat-A-Count, and GammaCoat) showed greater precision than the two-step procedures (GammaCoat and Spiria). Results by the latter two techniques, however, correlated better with those by equilibrium dialysis than did those by the analog methods or by TT4/TBG. Only the GammaCoat two-step method had a slight but statistically significant (inverse) correlation with TBG concentration. All three analog methods and TT4/TBG showed a marked dependence on albumin concentration, whereas the Spiria technique showed only a slight dependence. Only equilibrium dialysis was independent of both the TBG and albumin concentration. Thus, despite their good precision, the analog (one-step) FT4 methods and the TT4/TBG approach cannot be expected to produce valid results when the concentration of albumin in serum is abnormally low or high.

Hapten-heterologous conjugates evaluated for application to free thyroxine immunoassays

1993 ◽  
Vol 39 (2) ◽  
pp. 256-262 ◽  
Author(s):  
M J Khosravi ◽  
A Papanastasiou-Diamandi
Keyword(s):  
Solid Phase ◽  
Free Thyroxine ◽  
Clinical Samples ◽  
Time Resolved ◽  
Standard Curve ◽  
Sequential Binding ◽  
One Step ◽  
Titration Step ◽  
The One ◽  
Derivatives Of

Abstract We evaluated the effect of hapten heterology on free thyroxine (FT4) immunoassays involving the biotin-streptavidin system and time-resolved fluorometry. We compared protein derivatives of thyroxine (T4) and triiodothyronine (T3) as solid-phase antigen or biotinylated protein-tracer conjugate for competitive (or sequential) binding to a mouse anti-T4 monoclonal antibody. In both one- and two-step assays, the heterologous combination of the antibody and T3 conjugates showed superior standard curve sensitivity but up to eightfold lower zero standard signal (B(o)) when the same amounts of antibody and conjugates were used. The improved sensitivity was not altered when the amount of coupled T3 was increased to obtain a B(o) value similar to that of the homologous combination of antibody and T4 conjugates. In the two-step format, the sensitivity of the homologous assay was insufficient for routine use, consistent with displacement of bound T4 during the antibody back-titration step (demonstrated in the T4 displacement experiment with excess conjugate). Results from the one-step (labeled antibody) heterologous assay for approximately 85 clinical samples correlated well with those from an immunofluorometric assay and a two-step radioimmunoassay. The assay was not affected by a wide variation in endogenous serum concentrations of T4-binding globulin and albumin.

Time-resolved fluoroimmunoassay of human choriogonadotropin.

1983 ◽  
Vol 29 (1) ◽  
pp. 60-64 ◽  
Author(s):  
K Pettersson ◽  
H Siitari ◽  
I Hemmilä ◽  
E Soini ◽  
T Lövgren ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Solid Phase ◽  
Cross Reactivity ◽  
Sandwich Assay ◽  
Time Resolved ◽  
Alpha Subunits ◽  
Human Choriogonadotropin ◽  
Step Procedure ◽  
One Step ◽  
The One

Abstract We describe time-resolved fluoroimmunoassay for human choriogonadotropin involving monoclonal antibodies directed against the beta- and alpha-subunits. The latter antibody was labeled with europium, which was measured by counting for 1 s after the immunoreaction was completed. In the solid-phase sandwich assay, both a one-step and two-step procedure were used; the respective measuring ranges were 0.7-135 and 0.7-350 int. units/L, the latter covering a 500-fold dynamic range. The CV within the assay range was between 4 and 8%, depending on the dose. Cross reactivity with lutropin in the one- and two-step procedures was 1.6% and 1.0%, respectively.

Meaning of serum free-thyroxin values in nonthyroidal illnesses: seven methods compared.

1983 ◽  
Vol 29 (12) ◽  
pp. 2091-2093 ◽  
Author(s):  
D W Chan ◽  
J M Waud ◽  
E Taylor ◽  
J Stem ◽  
H Drew ◽  
...  
Keyword(s):  
Enzyme Inhibitor ◽  
Equilibrium Dialysis ◽  
The Other ◽  
Free T4 ◽  
Serum Free ◽  
One Step ◽  
Dialysis Method

Abstract Serum free thyroxin (FT4) was determined in 40 patients with various nonthyroidal illnesses. We studied seven methods: (1) a free thyroxin index calculated from total T4 and triiodothyronine resin uptake; (2) a free T4 index determined by enzyme inhibitor assays (Abbott's "Tetrazyme" and "Thyrozyme"); (3) a free T4 index calculated from total T4 and thyroxin-binding globulin; (4) free T4 by equilibrium dialysis; (5) Amersham's free T4 RIA; (6) Clinical Assays' one-step free T4 RIA; and (7) Clinical Assays' two-step free T4 RIA. Approximately half of the free T4 results were in the euthyroid range and the other half in the hypothyroid range by methods 1, 2, 5, and 6. Results for free T4 by methods 3 and 7 were similar to those by equilibrium dialysis (method 4), the percentages of patients with results in the euthyroid range being 68%, 65%, and 76%, respectively.

Direct and indirect techniques for free thyroxin compared in patients with nonthyroidal illness. I. Effect of free fatty acids.

1989 ◽  
Vol 35 (1) ◽  
pp. 102-109 ◽  
Author(s):  
G Csako ◽  
M H Zweig ◽  
J Glickman ◽  
J Kestner ◽  
M Ruddel
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Solid Phase ◽  
Equilibrium Dialysis ◽  
Free Fraction ◽  
Molar Ratio ◽  
Nonthyroidal Illness ◽  
Binding Rate ◽  
Number Of Patients ◽  
One Step

Abstract We examined the effect of endogenous free fatty acids (FFA) on the measurement of free thyroxin (FT4) by five different methodologies represented in 16 different assays in a large number of patients with nonthyroidal illness (NTI). Some, but not all, one-step (analog) FT4 RIAs negatively correlated with FFA concentration. All two-step FT4 RIAs, equilibrium dialysis FT4, and the dialyzable (free) fraction of T4 positively correlated. In contrast, a binding-rate-based FT4 RIA, FT4 indices based on T3 macroaggregated albumin uptake, and T4/TBG ratios did not correlate. We also analyzed the FT4-FFA relationship with a second, more sensitive approach by correlating test results with FFA/albumin molar ratio as an estimate of the "excess" (nonalbumin bound) FFA. We found that all FT4 RIAs, equilibrium dialysis FT4, FT4 indices based on T3 uptake, the dialyzable fraction of labeled T4 in equilibrium dialysis, the fraction of labeled T4 bound to solid phase antibody in the binding-rate-based RIA, and T3 uptake correlated with the FFA/albumin molar ratio. This FFA dependency was comparable among all the various techniques and was relatively small. Thus, increases or decreases in FT4 results due to varying FFA (and albumin) concentrations are highly likely with most currently available methods (only the T4/TBG ratio did not reveal FFA-dependency), but the magnitude of changes varies with the "excess" FFA.

Sign in / Sign up

Export Citation Format

Share Document