A two-step radioimmunoassay for free triiodothyronine in serum.

1987 ◽  
Vol 33 (3) ◽  
pp. 372-376 ◽  
Author(s):  
M G Rajan ◽  
A M Samuel
Keyword(s):  
Pregnant Women ◽  
Solid Phase ◽  
Equilibrium Dialysis ◽  
Normal Subjects ◽  
Free Triiodothyronine ◽  
High Affinity ◽  
The Mean ◽  
Hyperthyroid Patients ◽  
Normal Adults ◽  
Good Agreement

Abstract Using a high-affinity solid-phase-bound antibody (Ka = 1.2 X 10(11) L/mol), we have standardized a two-step radioimmunoassay for free triiodothyronine (FT3) in serum, based on immunoextraction. The method was validated by comparison with an equilibrium-dialysis procedure (r = 0.96) involving RIA of T3 in the dialysate standardized with the same antibody and by a commercial (Liso-Phase, International-CIS) method. The two-step RIA could detect as little as 0.2 pg per milliliter. The mean CVs within and between assays were 9% and 12%, respectively. FT3 values measured in 30 normal adults ranged from 1.77 to 4.77 ng/L. Comparison with ratios of total T3 to thyroxin-binding globulin showed good agreement in normal subjects, pregnant women, and hypothyroid and hyperthyroid patients.

Enzyme immunoassay of free triiodothyronine in serum.

1987 ◽  
Vol 33 (1) ◽  
pp. 172-176 ◽  
Author(s):  
N Hata ◽  
K Miyai ◽  
Y Endo ◽  
Y Iijima ◽  
Y Doi ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Enzyme Immunoassay ◽  
Solid Phase ◽  
Equilibrium Dialysis ◽  
Reference Interval ◽  
Normal Range ◽  
Free Triiodothyronine ◽  
Normal Limits ◽  
The Mean ◽  
Measurable Range

Abstract In this new solid-phase antibody enzyme immunoassay for free triiodothyronine (FT3) in serum, beta-D-galactosidase conjugated to triiodothyronine is used. Results are uninfluenced by physiological concentrations of thyroxin-binding globulin or albumin. Results correlate well with those determined by equilibrium dialysis (r = 0.95). The mean CVs within and between assays were 6.1 and 9.5%, respectively. The measurable range of FT3 in serum is 0.7 to 26 ng/L; the normal reference interval is 1.9 to 8.9 ng/L. Concentrations of FT3 in serum of patients with hyperthyroidism were high; those of patients with hypothyroidism were within normal limits or low, and those of patients with congenitally decreased or increased TBG were within the normal range. In normal pregnant women, concentrations of FT3 as determined by radioimmunoassay correlated with those of albumin, declining as pregnancy progressed, but FT3 values determined by the proposed method or equilibrium dialysis were within the normal range and did not change during pregnancy.

THE "EFFECTIVE THYROXINE RATIO" – NEW IN VITRO TEST OF THYROID FUNCTION AND ITS CORRELATION WITH FREE THYROXINE

1974 ◽  
Vol 76 (1) ◽  
pp. 83-88 ◽  
Author(s):  
Janusz Nauman ◽  
Alicja Nauman
Keyword(s):  
Pregnant Women ◽  
Normal Subjects ◽  
Free Thyroxine ◽  
In Vitro Test ◽  
High Reproducibility ◽  
Vitro Test ◽  
The Mean ◽  
Hypothyroid Patients ◽  
Hyperthyroid Patients

ABSTRACT The effective thyroxine ratio (ETR) and absolute concentration of free thyroxine (AFT4) were estimated in the sera of 31 normal subjects, 27 hyperthyroid patients, 12 hypothyroid patients and 21 euthyroid pregnant women. The mean ETR value in the controls was 1.0 ± 0.18, in the hyperthyroid patients 1.31 ± 0.25, in the hypothyroid patients 0.71 ± 0.21 and in normal pregnant women 0.99 ± 0.24. The mean AFT4 in the normal subjects was 3.0 ± 0.53 ng/100 ml, in the hyperthyroid patients 9.49 ± 2.44 ng/ 100 ml, in the hypothyroid patients 0.58 ± 0.15 ng/100 ml and in the pregnant women 2.84 ± 0.63 ng/100 ml, respectively. High reproducibility of ETR and a significant positive correlation between ETR and AFT4 with r = 0.96 suggest that ETR might be a suitable in vitro test for routine clinical evaluation of the thyrometabolic state.

Diagnostic value of thyrotropin concentrations in serum as measured by a sensitive immunoradiometric assay.

1986 ◽  
Vol 32 (3) ◽  
pp. 461-464 ◽  
Author(s):  
F Bassett ◽  
C J Eastman ◽  
G Ma ◽  
G F Maberly ◽  
H C Smith
Keyword(s):  
Monoclonal Antibodies ◽  
Pregnant Women ◽  
Solid Phase ◽  
Diagnostic Value ◽  
Immunoradiometric Assay ◽  
Highly Sensitive ◽  
Hospital Patients ◽  
The Mean ◽  
Seriously Ill ◽  
Hyperthyroid Patients

Abstract A new, highly sensitive immunoradiometric thyrotropin (TSH) assay involving solid-phase-coupled monoclonal antibodies (Boots-Celltech Sucrosep IRMA-TSH) has been evaluated in a wide variety of patients with thyroidal and nonthyroidal illnesses and the results compared with those obtained by conventional diagnostic TSH RIAs. The sensitivity of the present assay ranged from 0.036 to 0.1 milli-int. unit/L (mean 0.056). TSH, measurable in serum of each of 128 euthyroid patients, ranged from 0.1 to 6.3 milli-int. units/L (mean 1.7, SD 1.1). Similar concentrations were found in 15 healthy pregnant women. TSH was undetectable in 27 hyperthyroid patients, of whom six were tested with thyroliberin stimulation and failed to respond. The mean TSH concentration measured in 62 seriously ill hospital patients of 2.7 (SD 2.5) milli-int. units/L was significantly higher (p less than 0.05) than in the euthyroid patients. Basal values and peak TSH responses to thyroliberin testing correlated well (r = 0.63, n = 48), irrespective of clinical diagnosis. We conclude that the present assay readily discriminates between euthyroid and hyperthyroid patients and should replace conventional TSH RIAs in diagnostic laboratories.

Effect of stripping thyroxin from thyroxin-binding globulin on the measurement of free thyroxin in serum by equilibrium dialysis and by radioimmunoassay

1990 ◽  
Vol 36 (2) ◽  
pp. 313-318 ◽  
Author(s):  
T Nakagawa ◽  
K Matsumura ◽  
K Takeda ◽  
N Shinoda ◽  
A Matsuda ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Equilibrium Dialysis ◽  
Normal Subjects ◽  
Sample Volume ◽  
Dilution Factor ◽  
Free T4 ◽  
Mean Values ◽  
Patient Groups ◽  
The Mean ◽  
Influence Measurement

Abstract In considering factors that might influence measurement of free thyroxin (T4), we evaluated the proportion (%) of T4 that could be stripped from thyroxin-binding globulin (TBG). The percentage of free T4 was measured in serially diluted sera from four normal subjects, four patients with hyperthyroidism or hypothyroidism, four pregnant women, and four malnourished subjects with low TBG. The critical percentage of stripping was determined by the product of the percentage free T4 and the critical dilution factor (the point where the percentage free T4 began to decrease). The mean values obtained for the respective patient groups--6.38%, 2.76%, 16.73%, 9.75%, and 4.28%--were proved to be related to the rate of saturation of TBG with T4. Values for percentage stripping determined with the "GammaCoat two-step RIA" and the "LiquiSol RIA" were well within the critical percentage stripping by equilibrium dialysis, except in the case of low-TBG serum as measured by LiquiSol RIA. Free T4 concentration as measured by LiquiSol RIA decreased as sample volume decreased. These findings were ascribed to the relatively high values for percentage stripping in the LiquiSol RIA, which led to erroneously low values for free T4.

Chemically blocked analog assays for free thyronines. II. Use of equilibrium dialysis to optimize the displacement by chemical blockers of T4 analog and T3 analog from albumin while avoiding displacement of T4 and T3 from thyroxin-binding globulin.

1988 ◽  
Vol 34 (1) ◽  
pp. 17-23 ◽  
Author(s):  
L R Witherspoon ◽  
A S el Shami ◽  
S E Shuler ◽  
H Neely ◽  
R Sonnemaker ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Equilibrium Dialysis ◽  
Clinical Results ◽  
Antibody Binding ◽  
Albumin Binding ◽  
Free Triiodothyronine ◽  
Hyperthyroid Patients

Abstract Chemical blockers used to displace thyronine analog from albumin in analog kits for assay of free thyroxin (FT4) or free triiodothyronine (FT3) may also displace thyroxin (T4) or triiodothyronine (T3) from thyroxin-binding globulin (TBG), resulting in an apparent TBG dependence of results of free hormone estimates. We used equilibrium dialysis and antibody binding to assess the displacement of thyronine analogs and thyronines from albumin and TBG by use of chemical blockers. We chose a combination of two chemical blockers, which eliminated thyronine analog-albumin binding but minimized thyronine displacement from TBG for use in FT4 and FT3 assays. These blocked-analog free-hormone assays yielded accurate clinical results in euthyroid patients, hypo- and hyperthyroid patients, and in pregnant women. FT4 results were not entirely normalized in all nonthyroidally ill patients, indicating that decreased analog-albumin binding is not the only factor resulting in low FT4 results. In current Diagnostic Products Corp. (DPC) FT4 and FT3 blocked-analog kits, the blocker concentrations are the same as we used in these assays.

scholarly journals Functional Status of Maternal Thyroid Gland in Eclampsia

2019 ◽  
Vol 31 (1) ◽  
pp. 9-14
Author(s):  
M Hafizur Rahman ◽  
Mahbub Ara Chowdhury ◽  
Shahin Mahmuda
Keyword(s):  
Pregnant Women ◽  
Normal Pregnancy ◽  
Hormonal Changes ◽  
Free Triiodothyronine ◽  
College Hospital ◽  
Medical College ◽  
The Mean ◽  
Maternal Thyroid ◽  
Complicated Pregnancy ◽  
In Pregnancy

Marked changes in maternal thyroid activity occur in pregnancy. During pregnancy bodily hormonal changes and metabolic demands result in complex alteration in the bio-chemical parameters of thyroid activities. Besides these, thyroid enlargement, increased thyroid capability for iodine uptake and increase in basal metabolic rate are evidential though these findings are not usually associated with symptoms of hyperthyroidism in pregnancy. Serum concentration of thyroid hormone thyroxine and triiodothyronine in complicated pregnancy like eclamptic toxemia is another field of controversy. To evaluate the changes in thyroid function in normal pregnancy and eclamptic toxemia, a study was undertaken in Rajshahi Medical College Hospital. We collected serum specimens from non pregnant but married women, normal 3rd trimester pregnant women and patients with eclampsia at 3rd trimester of pregnancy and measured serum concentrations of total and free thyroxine (TT4 & FT4) and total and free triiodothyronine (TT3 & FT3 ) by using RIA. Among the study subjects, 10 women were married but non pregnant, 12 women were in their 3rd trimester of normal pregnancy and 32 patients of eclamptic toxemia with 3rd trimester of pregnancy. In normal pregnancy, FT4 and FT3 levels remained normal while TT4 and TT3 levels were elevated. In patients with toxemia of pregnancy, the mean serum TT3 concentration was significantly lower than that of normal pregnancy and the serum FT3 concentrations were below the normal pregnancy range. The mean serum TT4 and FT4 concentrations in patients with eclampsia were however, significantly higher than those in normal pregnant women. TAJ 2018; 31(1): 9-14

An improved ultrafiltration method for free thyroxine and triiodothyronine in serum.

1980 ◽  
Vol 26 (1) ◽  
pp. 159-162 ◽  
Author(s):  
J Sophianopoulos ◽  
I Jerkunica ◽  
C N Lee ◽  
D Sgoutas
Keyword(s):  
Radiochemical Purity ◽  
Specific Activity ◽  
Equilibrium Dialysis ◽  
Free Ligand ◽  
High Specific Activity ◽  
Free Thyroxine ◽  
Free Triiodothyronine ◽  
Men And Women ◽  
Adult Men ◽  
Hyperthyroid Patients

Abstract We describe an ultrafiltration technique for rapidly and directly determining free triiodothyronine or free thyroxine, or both. After equilibrating serum at 37 degrees C with purified tracer of high specific activity, we placed 0.15 mL of serum in 2.8 mL of phosphate buffer (0.1 mol/L, pH 7.4) in the ultrafiltration cell and obtained successive 0.2- and 0.6-mL fractions of protein-free ultrafiltrate. Under our conditions free ligand concentration was independent of flow rate. After purifying the second fraction with protein-coated charcoal, we could determine the proportion of free triiodothyronine or free thyroxine. Samples from normal adult men and women, including women who were taking oral contraceptives or were pregnant, and from hypo- and hyperthyroid patients gave results that agreed with those obtained by equilibrium dialysis. Speed is the main advantage of the method: one technologist can complete the procedure in 2 h and, using a multi-micro-ultrafiltration system, can process many samples in one day. For laboratories where index-type reactions are performed routinely and direct free triiodothyronine or free thyroxine is determined only on selected specimens, this method is superior to dialysis. It is also very convenient for rapidly purifying tracers, to at least 97% radiochemical purity, with 94% recovery and no dilution.

TRIIODOTHYRONINE AND THYROXINE NUCLEAR RECEPTORS IN LYMPHOCYTES FROM NORMAL, HYPER- AND HYPOTHYROID SUBJECTS

1977 ◽  
Vol 85 (1) ◽  
pp. 44-54 ◽  
Author(s):  
Th. Lemarchand-Béraud ◽  
A.-Ch. Holm ◽  
B. R. Scazziga
Keyword(s):  
Nuclear Receptors ◽  
Binding Sites ◽  
Intact Cell ◽  
Affinity Constant ◽  
Limited Capacity ◽  
Intact Cells ◽  
High Affinity ◽  
The Mean ◽  
Hypothyroid Patients ◽  
Hyperthyroid Patients

ABSTRACT In an investigation of thyroxine (T4) and triiodothyronine (T3) receptors in humans, the lymphocyte was chosen as the target cell. This study was performed to elucidate whether T3 and T4 bind to different receptors, if T4 is bound only after conversion into T3, and whether there is any modification of the receptors in hyper- and hypothyroidism. Lymphocytes were found to possess a high-affinity, limited-capacity binding sites for both T4 and T3. The mean equilibrium affinity constant (Ka) was 2.28 · 1010 ± 0.21 m−1 for T3, and 0.98 · 1010 ± 0.16 m−1 for T4. The mean number of saturable binding sites was 115 for T3, and 102 for T4. The binding capacities and affinities also determined in the lymphocyte nuclei isolated after incubation of the intact cell, were similar to those observed in the intact cells. In competition experiments, labelled T4 was as readily displaced by T3 as by T4 itself, whereas labelled T3 was displaced only by a 40 times higher concentration of T4 than T3. These observations suggest identical receptors for the two hormones and a binding of T4 as such, provided it is not in competition with T3. In lymphocytes from hyperthyroid patients, receptor affinities and numbers remained unchanged. In lymphocytes from hypothyroid patients, the affinity was normal, but the mean number of T3 binding sites was increased to 310 (P < 0.001), to return to normal after a few months of treatment.

Discrepancies between serum free triiodothyronine and free thyroxin as measured by equilibrium dialysis and analog radioimmunoassay in nonthyroidal illnesses.

1984 ◽  
Vol 30 (5) ◽  
pp. 760-762 ◽  
Author(s):  
K Liewendahl ◽  
S Tikanoja ◽  
T Helenius ◽  
M Välimäki
Keyword(s):  
Serum Albumin ◽  
Equilibrium Dialysis ◽  
Healthy Controls ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
The Mean

Abstract We determined free triiodothyronine (FT3) and free thyroxin (FT4) in serum of patients with various nonthyroidal illnesses (NTI), by both commercial analog-type radioimmunoassays (A) and new equilibrium dialysis procedures (D). The mean FT3 was significantly lower in NTI by both techniques, but the decreases were of different magnitudes. The FT3(D):FT3(A) ratio was 1.96, vs 1.11 for healthy controls. In NTI the mean FT4(D) was somewhat increased, whereas the mean FT4(A) was much lower than normal, the above ratio being 1.70, vs 0.92 for controls. We ascribe these discrepancies, at least in part, to binding of radiolabeled T3- and T4-analog tracers to serum albumin.

Enzyme immunoassay of free thyroxin in serum.

1984 ◽  
Vol 30 (10) ◽  
pp. 1682-1685 ◽  
Author(s):  
M Ito ◽  
K Miyai ◽  
K Doi ◽  
H Mizuta ◽  
N Amino
Keyword(s):  
Pregnant Women ◽  
Enzyme Immunoassay ◽  
Equilibrium Dialysis ◽  
Normal Adult ◽  
Double Antibody ◽  
Low Concentrations ◽  
The Mean ◽  
Measurable Range

Abstract We describe a double-antibody enzyme immunoassay for free thyroxin (FT4) in serum with use of beta-D-galactosidase conjugated to thyroxin. The method is uninfluenced by thyroxin-binding globulin or albumin. Values for FT4 so determined correlated well with those determined by radioimmunoassay (r = 0.98) and equilibrium dialysis (r = 0.89). The mean variability (CV) within and between assays was 7.4% and 7.6%, respectively. The measurable range of FT4 in serum was 2.8 to 109 ng/L. The FT4 concentrations in serum as determined by this method were 8.4 to 15.5 ng/L for 26 normal adult subjects; 26 to greater than 109 ng/L for 10 patients with hyperthyroidism; less than 2.8 to 8.0 ng/L for seven patients with hypothyroidism; 7.3 to 15.8 ng/L for eight pregnant women; and 12.2 and 13.5 ng/L for two patients with low concentrations of thyroxin-binding globulin.

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