DETERMINATION OF TOTAL AND FREE SERUM THYROXINE IN THYROID DISEASES

1971 ◽  
Vol 67 (4) ◽  
pp. 793-800 ◽  
Author(s):  
K. Liewendahl ◽  
J. Tötterman ◽  
B.-A. Lamberg
Keyword(s):  
Rapid Method ◽  
Clinical Laboratory ◽  
Normal Values ◽  
Free Thyroxine ◽  
Free Thyroxine Index ◽  
Total Thyroxine ◽  
Competitive Protein Binding ◽  
Free Serum ◽  
Good Linear Correlation

ABSTRACT The free thyroxine fraction in serum was determined by means of a rapid method based on the uptake of radioactive thyroxine by Sephadex (T4U). The corresponding values for percentage free thyroxine (PFT4) were obtained by simultaneous determination of the dialysable fraction. A good linear correlation was established between the two methods. Serum total thyroxine (T4) was determined by the competitive protein-binding technique. The concentration of the absolute free thyroxine (AFT4) was calculated. Of the three laboratory parameters tested, AFT4 showed the highest discrimination in both hyper- and hypothyroidism. The »free thyroxine index«, FT4I, which is a product of T4 and T4U, proved equally useful. Good results were also obtained with T4, whereas PFT4 showed the largest overlap with the normal values. PFT4 is important, however, for the calculation of AFT4. The rapid method for determination of the free thyroxine fraction described in this paper is suitable for routine use in the clinical laboratory.

Evaluation of a Kit (Thyrolute) for the Combined Determination of Serum Total Thyroxine and Sequential Free Thyroxine Index using Sephadex G-25 and 125I-thyroxine

1975 ◽  
Vol 12 (1-6) ◽  
pp. 200-206 ◽  
Author(s):  
P. J. N. Howorth ◽  
C. G. McKerron ◽  
P. Marsden
Keyword(s):  
Normal Subjects ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Thyroid Status ◽  
Two Stage ◽  
Accuracy And Precision ◽  
Free Thyroxine Index ◽  
Total Thyroxine ◽  
Similar Accuracy

A new kit (Thyrolute, Ames) for the combined determination of serum total thyroxine (T-4) and sequential free thyroxine index (F.T.I.) using Sephadex G-25 and 125I-thyroxine was evaluated in 136 patients and normal subjects. The T-4 determination was virtually identical to that used in the Ames Tetralute kit and had a similar accuracy and precision. The sequential F.T.I. was compared with a two-stage F.T.I. The two F.T.I.s showed highly significant correlations in the various groups of patients except euthyroid women with raised thyroxine-binding globulin (TBG) (pregnant or oral contraceptive). The overlap found for the sequential F.T.I. between euthyroid, hypothyroid, and thyrotoxic patients was slightly inferior (9%) to that found with the two-stage F.T.I. (6%), but its diagnostic success rate was higher than that of the serum T-4 determination alone. Serial observations of serum T-4 and sequential F.T.I. were also made on eight patients receiving carbimazole therapy for hyperthyroidism. The sequential F.T.I. showed complete parallelism with serum T-4 regardless of thyroid status, so that it was of no practical value in these patients. It was concluded that the sequential F.T.I kit would be of most value in the smaller hospital laboratory lacking facilities for the radioimmunoassay of thyroid hormones and thyroid stimulating hormone.

scholarly journals Evaluation of free and total L-thyroxine in serum by a commercial procedure.

1981 ◽  
Vol 27 (1) ◽  
pp. 149-152 ◽  
Author(s):  
M J Obregon ◽  
A Kurtz ◽  
R Ekins ◽  
G Morreale de Escobar
Keyword(s):  
Pregnant Women ◽  
Plasma Proteins ◽  
Diagnostic Value ◽  
Free Thyroxine ◽  
Total Thyroxine ◽  
Dialysis Method ◽  
Hypothyroid Patients ◽  
Hyperthyroid Patients ◽  
Normal Controls

Abstract We assessed a commercial kit (Corning Medical) for "free" and total thyroxine determination, results being compared to those obtained by the Ekins and Ellis dialysis method (free thyroxine) and the method of Weeke and Orskov (total thyroxine). The kit procedure permits determination of both free and total thyroxine within 4 to 5 h, and the combined results may disclose changes in binding to plasma proteins that would be missed if only free thyroxine were determined. With both free-thyroxine methods, the values distinguished hyperthyroid patients from normal controls and pregnant women with 100% accuracy, but there was some overlap between hypothyroid patients and controls. Absolute values with the kit procedure often exceed those obtained by dialysis, especially for hypothyroid patients and pregnant women. We conclude that the kit may be of as much diagnostic value as the dialysis method if the limitations regarding absolute values are kept in mind and the test is not used as a substitute for thyrotropin determinations in cases of suspected hypothyroidism.

Pictorial reporting of multiple thyroid function results.

1976 ◽  
Vol 22 (10) ◽  
pp. 1562-1566
Author(s):  
R W Pain ◽  
B M Duncan
Keyword(s):  
Thyroid Function ◽  
Reporting System ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Testing Procedures ◽  
Function Tests ◽  
Free Thyroxine Index ◽  
Total Thyroxine ◽  
Experience Difficulty

Abstract Clinicians experience difficulty in correctly interpreting the results of in vitro thyroid function tests in the presence of abnormalities of thyrobinding proteins or when results are borderline. This difficulty has been largely resolved in our laboratory by three innovations. First, the borderline areas for each of three routine tests of thyroid function (total thyroxine, thyrobinding index, and free thyroxine index) were accurately determined. Second, the results from this routine profile of three tests were displayed pictorially so as to produce patterns characteristic of various diagnostic situations, including euthyroidism in the presence of abnormalities of thyrobinding proteins. Third, interpretive comments and, in the case of borderline patterns, suggested further testing procedures were added to the report. Clinicians find the reporting system helpful and respond when additional tests are suggested. The system, operated manually at first, was later computerized.

Radioimmunoassay for normalized thyroxine with use of Sephadex columns.

1977 ◽  
Vol 23 (12) ◽  
pp. 2324-2328 ◽  
Author(s):  
W T Goedemans ◽  
P C Bartels ◽  
A F Roijers
Keyword(s):  
Protein Binding ◽  
Present Method ◽  
Free Thyroxine ◽  
Thyroxine Binding Globulin ◽  
Free Thyroxine Index ◽  
Competitive Protein Binding ◽  
Barbital Buffer

Abstract We describe a reproducible radioimmunoassay, with use of Sephadex columns, for measuring normalized thyroxine. In comparison with a competitive protein-binding procedure, the present method is more specific because antibody rather than thyroxine-binding globulin is responsible for the competition between endogeneous and tracer thyroxine. In barbital buffer, various concentrations of thyroxine binding pre-albumin and albumin had no influence on the results. Values obtained by the present method correlated well with those by the free thyroxine index and a generally accepted thyroxine normalized method.

A Rapid Method for the Determination of Urea in Blood and Urine

1961 ◽  
Vol 7 (5) ◽  
pp. 488-493 ◽  
Author(s):  
Jacob M Levine ◽  
Raul Leon ◽  
Frederick Steigmann
Keyword(s):  
Rapid Method ◽  
Clinical Laboratory

Abstract A rapid method for the determination of urea in blood and urine based upon the urea-p-dimethylaminobenzaldehyde reaction is described. Results of determinations can be reported in 15 min. The method described is suitable for routine use in the clinical laboratory.

scholarly journals Comparison between Determination of Free Thyroxine Index and Effective Thyroxine Ratio in Human Serum

BMJ ◽  
1974 ◽  
Vol 3 (5933) ◽  
pp. 708-711 ◽  
Author(s):  
E. G. M. D'Haene ◽  
F. J. L. Crombag ◽  
J. F. W. Tertoolen
Keyword(s):  
Human Serum ◽  
Free Thyroxine ◽  
Free Thyroxine Index

Dysthyronemia in normal concentrations of thyrotropin – analytical and clinical consequences

2013 ◽  
Vol 13 (2) ◽  
Author(s):  
Radovan Bílek ◽  
Luboslav Stárka ◽  
Václav Zamrazil
Keyword(s):  
Thyroid Hormones ◽  
Autoimmune Thyroid Disease ◽  
Reference Range ◽  
Normal Values ◽  
Free Fraction ◽  
Free Thyroxine ◽  
Autoimmune Thyroid ◽  
Total Triiodothyronine ◽  
Clinical Consequences

AbstractThis article discusses the conditions that may lead to a phenomenon called dysthyronemia. Here, the thyroid gland has concentration of thyrotropin in circulation within the reference range, but the concentrations of free or total fractions of thyroid hormones are outside the reference range. Normal values of thyrotropin (TSH) and increased values of THs are referred to as hyperthyroxinemia, while normal values of thyrotropin and decreased values of thyroid hormone are hypothyroxinemia. As shown by our observations, it is a relatively frequent situation in the parallel determinations of TSH and free thyroxine, when results verging on hyperthyroxinemia were found in 7% of cases (6.74%, n=259,590), and also in the parallel sets of TSH and total triiodothyronine when hypotriiodothyroninemia reached 8.5% (8.48%, n=73,143). We are assuming that the main cause of hyperthyroxinemia in the free thyroxine and TSH system is the presence of autoantibodies against thyroxine in patients with autoimmune thyroid disease. The reason of hypotriiodothyroninemia in the system of triiodothyronine and TSH is a decreased concentration of thyroid binding globulin in postmenopausal women. Manufacturers of immunoanalytical kits should take into account the potential adverse effects of autoantibodies against thyroid hormones when measuring the results of immunoassay determination of the free fraction of these hormones.

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