A Comparison of Serum Thyroxine [T4(D)], RT3U Ratio and T4-RT3 Index with Radioiodine Uptake in the Triiodothyronine Suppression Test

1972 ◽  
Vol 11 (04) ◽  
pp. 317-323
Author(s):  
R. Höschl ◽  
T. M. D. Gimlette
Keyword(s):  
Free Thyroxine ◽  
Radioiodine Uptake ◽  
Serum Thyroxine ◽  
Before And After ◽  
Free Thyroxine Index ◽  
Suppression Test

SummaryA total of 132 triiodothyronine suppression tests were performed using 100 μg of T3 for 7 days. Radioiodine uptake at four hours, serum thyroxine [T4(D)], T3 binding coefficient [RT3U ratio] and free thyroxine index [T4-RT3 index] were estimated before and after a course of triiodothyronine.T4(D) decreased significantly in only 38.4% of T3 suppression tests assessed as positive by the decrease in radioiodine uptake; it did not change or increased significantly in 84.7% of tests negative by radioiodine uptake.RT3U ratio showed little change in all groups. The changes in T4-RT3 index were similar to those of T4(D).The correlation of changes in T4(D) with 4 hour radioiodine uptake is poor (r = 0.34).Agreement between changes in radioiodine uptake and T4(D) was observed only in 54% of tests; between changes in uptake and T4-RT3 index in 69.4%.Estimation of serum thyroxine or free thyroxine index in the T3 suppression test cannot substitute for the radioiodine uptake for reasons which are discussed.

A Comparison of Serum Thyroxine [T4(D)], RT3U Ratio and T4-RT3 Index with Radioiodine Uptake in the TSH Stimulation Test

1972 ◽  
Vol 11 (04) ◽  
pp. 324-332
Author(s):  
R. Höschl ◽  
T. M. D. Gimlette
Keyword(s):  
Free Thyroxine ◽  
Stimulation Test ◽  
Radioiodine Uptake ◽  
Serum Thyroxine ◽  
Positive Serum ◽  
Free Thyroxine Index ◽  
Reliable Parameter ◽  
Stimulation Tests ◽  
Tsh Stimulation ◽  
Better Than

SummaryA total of 236 TSH stimulation tests were performed using 10 units of TSH intramuscularly. 4 hour uptake of 132I, serum thyroxine [T4(D)], T3 binding coefficient [RT3U ratio] and free thyroxine index [T4-RT3 index] were estimated before and 18 hours after TSH.In 88 tests classified by radioiodine uptake change as positive serum thyroxine increased significantly in only 63.7%, T4-RT3 index in 61.5%.Out of 108 tests classified as negative by radioiodine uptake, serum thyroxine increased significantly in 14.8% and T4-RT3 index in 13.0%.The RT3U ratio procedure used was the least reliable parameter in testing thyroid response to TSH stimulation, T4RT3 index was no better than T4(D) alone.The change in serum thyroxine levels in response to TSH stimulation is in our opinion unreliable for the evaluation of TSH tests, and correlates poorly with changes in radioiodine uptake (r = 0.37), for reasons which are discussed.

DIAGNOSTIC VALUE OF SERUM THYROXINE AND FREE THYROXINE INDEX

2009 ◽  
Vol 194 (1-6) ◽  
pp. 341-348 ◽  
Author(s):  
K. Liewendahl ◽  
R. Ruutu ◽  
B.-A. Lamberg
Keyword(s):  
Diagnostic Value ◽  
Free Thyroxine ◽  
Serum Thyroxine ◽  
Free Thyroxine Index

Thyroid-Function Tests in Diphenylhydantoin-Treated Patients

1975 ◽  
Vol 21 (10) ◽  
pp. 1388-1392 ◽  
Author(s):  
Melvin R Stjernholm ◽  
Robert N Alsever ◽  
Merritt C Rudolph
Keyword(s):  
Clinical Status ◽  
Normal Subjects ◽  
Normal Serum ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Binding Assays ◽  
Normal Range ◽  
Drug Interference ◽  
Serum Thyroxine ◽  
Free Thyroxine Index

Abstract We compared the free-thyroxine index in normal adults and in euthyroid patients taking diphenylhydantoin. All subjects had normal serum thyrotropin concentrations. Serum thyroxine concentrations were determined by two commonly used competitive protein-binding assays, which yielded slightly different values, but which consistently showed the same degree of decrease in mean serum thyroxine concentration in drug-treated patients as compared to the normal subjects. When 14C-labeled diphenylhydantoin was added to serum before the assay, it was separated from thyroxine in the Ames method, whereas by the Murphy-Pattee method both drug and thyroxine were extracted together. Thus, the decrease in serum thyroxine concentrations during diphenylhydantoin therapy cannot be the result of drug interference with the binding of thyroxine to binding proteins in the assays. Triiodothyronine uptake, evaluated by two methods, was identical in the two groups. The free-thyroxine indexes for all normal persons were within the manufacturer's normal range, but 21% of the drug-treated patients had subnormal indexes by the Ames method; the indexes as measured by the Murphy— Pattee method were in the lower half of the normal range. Because the triiodothyronine uptake was unaffected by the drug treatment, the decreases in the indexes must have resulted from the lower serum thyroxine concentrations. We conclude that the free-thyroxine index may not provide a valid estimate of either the clinical status or the free-thyroxine concentration in patients taking diphenylhydantoin.

Evaluation of serum triiodothyronine and adjusted triiodothyronine (free triiodothyronine index) in pregnancy.

1977 ◽  
Vol 23 (3) ◽  
pp. 490-492 ◽  
Author(s):  
M E Parslow ◽  
T H Oddie ◽  
D A Fisher
Keyword(s):  
Free Thyroxine ◽  
Free Triiodothyronine ◽  
Thyroxine Binding Globulin ◽  
Serum Thyroxine ◽  
Free Thyroxine Index ◽  
Total Triiodothyronine ◽  
Total Thyroxine ◽  
Highly Correlated ◽  
Normal Men ◽  
Male Subjects

Abstract We measured serum thyroxine (free and total), triiodothyronine (free and total), thyroxine-binding globulin, and triiodothyronine uptake by talc in 97 normal men and 50 pregnant women. Mean serum thyroxine and triiodothyronine concentrations were higher in the pregnant subjects (104 vs. 78 mug/liter and 1.69 vs. 1.30 mug/liter) because of a higher mean thyroxine-binding globulin concentration (70 vs. 38 mg/liter). Mean triiodothyronine uptake by talc was lower in the pregnant subjects (0.82 vs. 1.03). Mean free thyroxine concentrations were similar in the two groups, but mean free triiodothyronine concentrations were 10% lower in the pregnant subjects. Triiodothyronine uptake by talc and the diayzable thyroxine and triiodothyronine fractions were highly correlated (r = 0.85 and r = 0.82, P less than 0.001). Calculated free thyroxine index and free triiodothyronine index values (hyroxine and triiodothyronine indirectly adjusted, using triiodothyronine talc uptake to compensate for differences in thyroxine-binding globulin concentration), were statistically similar (84 vs. 82 and 1.38 vs. 1.34) in pregnant and male subjects. The results indicate that the total triiodothyronine concentration can be normalized on the basis of the triiodothyronine uptake by talc to correct for variations in thyroxine-binding globulin concentration.

Serum free thyroxine in patients with T3-toxicosis

1985 ◽  
Vol 110 (3) ◽  
pp. 354-359 ◽  
Author(s):  
Enio Martino ◽  
Alessandro Pacchiarotti ◽  
Fabrizio Aghini-Lombardi ◽  
Lucia Grasso ◽  
Giovanni Bambini ◽  
...  
Keyword(s):  
Clinical Evidence ◽  
Elevated Serum ◽  
Normal Serum ◽  
Free Thyroxine ◽  
Total Serum ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Serum Thyroxine ◽  
Free Thyroxine Index ◽  
Serum Free Thyroxine

Abstract. The serum free thyroxine concentration was measured by direct radioimmunoassay in 38 untreated T3-thyrotoxic patients with elevated serum total and free triiodothyronine, normal serum thyroxine and free thyroxine index, no TSH response to TRH, and with clinical evidence of hyperthyroidism. An elevation of circulating free thyroxine values was observed in 58% of the patients, whereas total serum thyroxine concentration was within the normal range. It is suggested, therefore, that T3-thyrotoxicosis should be reserved for patients with elevated serum total T3 and free T3 concentrations and normal serum total T4 and free T4 concentrations. Serum thyroxine-binding globulin concentrations were significantly lower (P < 0.025) in patients with an elevated serum free thyroxine (18.7 ± 3.6 μg/ml: mean ± sd) as compared with those in patients with a normal free thyroxine concentration (23.4 ± 2.6 μg/ml). In addition, no daily fluctuations in total and free thyroxine concentration were observed in 6 patients over a 4–8 day period.

Thyroid Function in Respiratory Distress Syndrome (RDS) of the Newborn

PEDIATRICS ◽  
1974 ◽  
Vol 54 (4) ◽  
pp. 423-428
Author(s):  
Ralph A. Redding ◽  
Celina Pereira
Keyword(s):  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Thyroid Function ◽  
Gestational Age ◽  
Distress Syndrome ◽  
Newborn Infants ◽  
Free Thyroxine ◽  
Total Serum ◽  
Serum Thyroxine ◽  
Free Thyroxine Index

Preliminary evaluation of thyroid function, utilizing total serum thyroxine (T4) and triiodothyronine (T3) resin uptake, was assessed following delivery in three groups of babies and their respective mothers; 40 premature new-borns with respiratory distress syndrome (RDS), 39 prematures comparable by gestational age who failed to develop RDS, and 22 full-term normal babies. The group of premature newborn infants in whom RDS occurred, as compared to the other two groups, had significantly lower mean total serum thyroxine levels and "free thyroxine index" (T4 x %T3 uptake/100). When matched by gestational age, the differences were also significant. Two days following delivery, the total serum T4 in the surviving prematures with RDS as compared to prematures without RDS was also significantly lower. The mean values for total T4 and "free thyroxine index" in the respective mothers of the three groups were not significantly different. Since L-thyroxine has been shown to increase the production of lung surfactant, widely accepted as deficient in RDS newborn infants, an association between lung immaturity and fetal thyroid function is postulated.

Free-Thyroxine Index in Schizophrenic Patients before and after Neuroleptic Treatment

1980 ◽  
Vol 6 (1) ◽  
pp. 29-33 ◽  
Author(s):  
F. Rinieris ◽  
G.N. Christodoulou ◽  
A. Souvatzoglou ◽  
D.A. Koutras ◽  
C. Stefanis
Keyword(s):  
Free Thyroxine ◽  
Neuroleptic Treatment ◽  
Before And After ◽  
Free Thyroxine Index ◽  
Schizophrenic Patients
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