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.

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.

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.

Lacking evidence for release of thyroid hormones from circulating thyroglobulin during subtotal thyroidectomy

1988 ◽  
Vol 117 (2) ◽  
pp. 219-224 ◽  
Author(s):  
J. Date ◽  
M. Blichert-Toft ◽  
U. Feldt-Rasmussen ◽  
V. Haas
Keyword(s):  
Thyroid Hormones ◽  
Mean Value ◽  
Thyroid Stimulating Hormone ◽  
Mean Values ◽  
Thyroid Resection ◽  
Free Thyroxine Index ◽  
Total Triiodothyronine ◽  
Total Thyroxine ◽  
The Mean ◽  
Peak Value

Abstract. The effect of subtotal thyroid resection for thyrotoxicosis on concentrations of serum thyroid hormones and thyroglobulin (Tg), was determined in 10 patients during operation and the subsequent 18 days. Mean serum Tg responded drastically, increasing from a pre-operative value of 0.30 nmol/l to a peak value of approximately 26 nmol/l during operation followed by a gradual decline to levels lower than before surgery on day 18. Mean serum total thyroxine was 114 nmol/l pre-operatively and free thyroxine index (FT4I) 105 units. Both fluctuated only slightly during operation. Postsurgically, the mean values decreased to below 50% of the pre-operative level. Mean serum total triiodothyronine (TT3) was 1.46 nmol/l pre-operatively. It decreased during operation, reaching a nadir of 0.55 nmol/l on day 2, whereafter the concentration increased slightly. Mean serum reverse T3 (rT3) was 0.45 nmol/l pre-operatively, increased 62% during surgery, and decreased postsurgically. The mean value of serum thyroid stimulating hormone (TSH) was 0.61 mU/l pre-operatively and remained below 1 mU/l during and after operation, but from day 10 concentration began to rise steadily. It is concluded that the vast release of Tg during thyroid resection did not contribute to the concentration of serum T4 to an extent of clinical relevance.

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

Comparison of Laboratory Test Results for Assessing Thyroid Function in Normal Subjects and Treated and Untreated Hyper- and Hypothyroid Patients

1971 ◽  
Vol 17 (3) ◽  
pp. 174-182 ◽  
Author(s):  
Norman D Lee ◽  
Boris Catz ◽  
M S Margolese ◽  
Vincent J Pileggi
Keyword(s):  
Binding Capacity ◽  
Normal Subjects ◽  
Free Thyroxine ◽  
Significant Finding ◽  
Normal Limits ◽  
Laboratory Test Results ◽  
Free Thyroxine Index ◽  
Normal Women ◽  
Normal Men ◽  
Hypothyroid Patients

Abstract Various indexes of thyroid status were measured in sera from normal men and women, normal women who were using oral contraceptives, hyper- and hypothyroid patients, and hypothyroid patients being successfully managed with various forms of replacement therapy. Total circulating thyroxine concentrations were measured by three methods as well as the thyroxine-binding capacity of the serum inter-alpha globulin, "free" thyroxine, and "free" thyroxine index. Our purpose was to compare the various measurements, and to assess their diagnostic usefulness. The most significant finding was that, of 197 hypothyroid patients, all of whom possessed total circulating thyroxine concentrations within normal limits, 28% showed subnormal "free" thyroxine concentrations.

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