Free thyroxine, free triiodothyronine, and thyrotropin concentrations in hypothyroid and thyroid carcinoma patients receiving thyroxine therapy

1987 ◽  
Vol 116 (3) ◽  
pp. 418-424 ◽  
Author(s):  
K. Liewendahl ◽  
T. Helenius ◽  
B.-A. Lamberg ◽  
H. Mähönen ◽  
G. Wägar
Keyword(s):  
Thyroid Carcinoma ◽  
Equilibrium Dialysis ◽  
Primary Hypothyroidism ◽  
Free Thyroxine ◽  
Suppressive Therapy ◽  
Free Triiodothyronine ◽  
Thyroxine Therapy ◽  
Thyroxine Replacement ◽  
Hypothyroid Patients ◽  
Serum Tsh

Abstract. Free thyroxine (FT4) and free triiodothyronine (FT3) concentrations in serum were measured by direct equilibrium dialysis methods in patients receiving thyroxine replacement or suppression therapy. Four of 50 hypothyroid patients euthyroid on replacement therapy (mean thyroxine dose 120 μg/day) had supra-normal FT4 concentrations, whereas the FT3 concentrations were normal in all. Forty-one of 56 operated thyroid carcinoma patients on suppressive therapy (mean thyroxine dose 214 μg/day) had raised FT4 concentrations, whereas the FT3 concentration was elevated in only one patient. There was a large difference in mean FT4 values for hypothyroid and thyroid carcinoma patients (17.2 vs 29.5 pmol/l), whereas the difference in mean FT3 values was small (5.0 vs 6.1 pmol/l), suggesting a decreased peripheral conversion of T4 to T3 with increasing concentrations of FT4. Serum TSH concentrations, as determined by an immunoradiometric assay, varied from < 0.02 to 11.9 mU/l in treated hypothyroid patients; 21 patients (42%) had values outside the reference limits. As a single test, serum TSH is therefore not very useful for the assessment of adequate thyroxine dosage in patients with primary hypothyroidism. In thyroid carcinoma patients, the TSH concentrations were < 0.18 mU/l; 45 patients had values < 0.02 mU/l indicating sufficient suppression of TSH secretion in the majority of cases. On the basis of these results we recommend the combination of FT3 and TSH tests for monitoring thyroxine replacement and suppression therapy. FT4 appears less useful than FT3 for this purpose even if special reference values values were adopted for each patient group.

scholarly journals Routine free thyroxine reference intervals are suboptimal for monitoring children on thyroxine replacement therapy and target intervals need to be assay-specific

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Elizabeth Wheeler ◽  
Kay Weng Choy ◽  
Lit Kim Chin ◽  
Nilika Wijeratne ◽  
Alan McNeil ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Reference Intervals ◽  
Clinical Diagnostics ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Free Triiodothyronine ◽  
Central Hypothyroidism ◽  
Thyroxine Replacement ◽  
Ortho Clinical Diagnostics ◽  
Serum Tsh

AbstractCentral hypothyroidism is a condition where there is (qualitatively or quantitatively) TSH deficiency, leading to reduced thyroid hormone production. In such patients, serum TSH does not accurately reflect the adequacy of thyroxine replacement, as the log-linear relationship between thyrotropin (TSH) and free thyroxine (FT4) is lost. We aimed to prospectively determine the optimal physiological FT4 treatment range for children treated for primary hypothyroidism, based on their serum TSH concentrations. This information could be used to guide optimal therapy for all children on thyroxine replacement, including those with central hypothyroidism. In total, sixty children (median age: 11 years, range: 11 months to 18 years) were recruited over 21 months. They were prescribed a stable dose of thyroxine for at least 6–8 weeks prior to a thyroid function test that consisted of serum TSH, FT4 and free triiodothyronine (FT3) measurements. The serum sample for the thyroid function tests was collected before ingestion of the daily dose, i.e. the trough concentration, and measured using Beckman Coulter UniCel DxI 800 instrument, Siemens Advia Centaur, Roche Cobas, Abbott Architect, Ortho Clinical Diagnostics Vitros 5600 (Ortho-Clinical Diagnostics, Raritan, NJ) platforms. The FT4 and FT3 reference intervals showed significant inter-method difference. The lower limit of the FT4 reference intervals were generally shifted mildly higher when the TSH concentration of the children were restricted from 0.5–5.0 mIU/L to 0.5–2.5 mIU/L. By contrast, the upper limit of the FT3 and FT4 reference intervals were relatively stable for the different TSH concentrations. Assay-specific target ranges for optimal thyroxine therapy are required until FT4 assay standardisation is realised.

Patients with Central Hypothyroidism are Less Sufficiently Treated with Levothyroxine than Patients with Primary Hypothyroidism

2021 ◽  
Author(s):  
Barbara Samec ◽  
Gaja Setnikar ◽  
Simona Gaberscek ◽  
Tomaz Kocjan
Keyword(s):  
Primary Hypothyroidism ◽  
Free Thyroxine ◽  
Free Triiodothyronine ◽  
Central Hypothyroidism ◽  
Tsh Levels

Abstract Background Contrary to patients with hypothyroidism after radioiodine (HRI) or after thyroidectomy (HTh), patients with central hypothyroidism (CH) cannot rely on thyrotropin (TSH) level to guide their treatment with L-thyroxine (L-T4). Consequently, they are at constant risk of under- or overtreatment. We aimed to establish the adequacy of L-T4 treatment in patients with CH in our cohort. Methods Consecutive patients with CH on L-T4 treatment were compared with patients adequately treated for HRI or HTh. Levels of free thyroxine (fT4) and free triiodothyronine (fT3) were evaluated and the fT4/fT3 ratio was calculated. Results Forty patients with CH, 136 patients with HRI and 43 patients with HTh were included in this study. Patients with HRI were significantly younger than patients with HTh and CH (p<0.001 for both). Levels of fT4 were significantly lower in CH than in adequately treated patients with HRI and HTh (median (range), 15.6 (12.7–21.3), 18.4 (12.2–28.8), and 18.7 (13.8–25.5) pmol/L, respectively, p<0.001 for both comparisons). Levels of fT3 did not differ significantly (p=0.521) between CH, HRI and HTh (median (range), 4.5 (2.7–5.9), 4.3 (3.2–6.2), and 4.4 (2.9–5.5) pmol/L, respectively). Accordingly, the fT4/fT3 ratio was significantly lower in the CH group than in HRI and HTh groups (median (range), 3.7 (2.5–5.2), 4.2 (1.2–7.7), and 4.4 (2.5–6.1), respectively, p<0.001 for both comparisons). Conclusions Patients with CH have lower fT4 levels and lower fT4/fT3 ratios than patients adequately treated for HRI or HTh. The cause for this difference may be the unreliable TSH levels in patients with CH.

Subclinical hypothyroidism

2011 ◽  
pp. 543-547
Author(s):  
Jayne A. Franklyn
Keyword(s):  
Thyroid Function ◽  
Subclinical Hypothyroidism ◽  
Expert Panel ◽  
Elevated Serum ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Free Triiodothyronine ◽  
Function Tests ◽  
Serum Tsh

Subclinical hypothyroidism is defined biochemically as the association of a raised serum thyroid-stimulating hormone (TSH) concentration with normal circulating concentrations of free thyroxine (T4) and free triiodothyronine (T3). The term subclinical hypothyroidism implies that patients should be asymptomatic, although symptoms are difficult to assess, especially in patients in whom thyroid function tests have been checked because of nonspecific complaints such as tiredness. An expert panel has recently classified individuals with subclinical hypothyroidism into two groups (1): (1) those with mildly elevated serum TSH (typically TSH in the range 4.5–10.0 mU/l) and (2) those with more marked TSH elevation (serum TSH >10.0 mU/l).

scholarly journals Misleading results from immunoassays of serum free thyroxine in the presence of rheumatoid factor

1997 ◽  
Vol 43 (6) ◽  
pp. 957-962 ◽  
Author(s):  
Anthony G W Norden ◽  
Rodwin A Jackson ◽  
Lorraine E Norden ◽  
A Jane Griffin ◽  
Margaret A Barnes ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Rheumatoid Factor ◽  
Equilibrium Dialysis ◽  
Thyroid Stimulating Hormone ◽  
Normal Serum ◽  
Free Thyroxine ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Serum Free Thyroxine ◽  
Stimulating Hormone

Abstract A novel interference with measurements of serum free thyroxine (FT4) caused by rheumatoid factor (RhF) is described. We found misleading, sometimes gross, increases of FT4 results in 5 clinically euthyroid elderly female patients with high RhF concentrations. All 5 patients had high FT4 on Abbott AxSYM® or IMx® analyzers. “NETRIA” immunoassays gave misleading results in 4 of the 5 patients; Amerlex-MAB® in 2 of 4 patients; AutoDELFIA®in 2 of the 5; and Corning ACS-180® and Bayer Diagnostics Immuno 1® in 1 of the 5. BM-ES700® system results for FT4 in these women remained within the reference range. Results for serum T4, thyroid-stimulating hormone, free triiodothyronine, thyroid-hormone-binding globulin, and FT4 measured by equilibrium dialysis were normal in all 5 patients. Drugs, albumin-binding variants, and anti-thyroid-hormone antibodies were excluded as interferences. Addition to normal serum of the RhF isolated from each of the 5 patients increased the apparent FT4 (Abbott AxSYM). Screening of 83 unselected patients demonstrated a highly significant positive correlation between FT4 (Abbott AxSYM) and RhF concentrations. Discrepant, apparently increased FT4 with a normal result for thyroid-stimulating hormone should lead to measurement of the patient’s RhF concentration.

Central and Peripheral Nerve Conduction in Thyroid Dysfunction: The Influence of l-Thyroxine Therapy Compared with Warming upon the Conduction Abnormalities of Primary Hypothyroidism

1983 ◽  
Vol 64 (6) ◽  
pp. 617-622 ◽  
Author(s):  
R. J. Abbott ◽  
B. P. O'Malley ◽  
D. B. Barnett ◽  
L. Timson ◽  
F. D. Rosenthal
Keyword(s):  
Peripheral Nerve ◽  
Nerve Conduction ◽  
Primary Hypothyroidism ◽  
Control Group ◽  
Conduction Delay ◽  
Evoked Responses ◽  
Visual Evoked Responses ◽  
Thyroxine Therapy ◽  
Hypothyroid Patients ◽  
Visual Evoked

1. The latencies of the visual evoked responses, indices of central nerve conduction, and peripheral nerve conduction were slowed in patients with primary hypothyroidism compared with controls. 2. in thyrotoxic patients, there was no change in the latencies of the visual evoked responses and peripheral nerve conduction compared with the control group. 3. The abnormalities seen in hypothyroidism were reversed by L-thyroxine therapy. 4. Warming untreated hypothyroid patients significantly improved both central and peripheral nerve conduction. 5. The conduction delay found in hypothyroidism is to a large extent dependent upon a subnormal body temperature.

Circadian thyrotropin variations are preserved in normal pregnant women

1995 ◽  
Vol 133 (1) ◽  
pp. 71-74 ◽  
Author(s):  
Elio Roti ◽  
Luigi Bartalena ◽  
Roberta Minelli ◽  
Mario Salvi ◽  
Eliana Gardini ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Pregnant Women ◽  
Free Thyroxine ◽  
Third Trimester ◽  
Circadian Variations ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
Trimester Pregnancy ◽  
Serum Tsh ◽  
Serum Free Thyroxine

Roti E, Bartalena L, Minelli R, Salvi M, Gardini E, Pistolesi A, Martino E, Braverman LE. Circadian thyrotropin variations are preserved in normal pregnant women. Eur J Endocrinol 1995;133:71–4. ISSN 0804–4643 Serum thyrotropin (TSH) concentration circadian rhythm is abolished in many endocrine and nonendocrine diseases. In the present study we have measured serum TSH concentration over 24 h every 2 h in second and third trimester pregnant women. During the 24-h period, serum free thyroxine and free triiodothyronine concentrations did not change significantly. In contrast, serum TSH concentrations demonstrated significant circadian variations both in the second and third trimester pregnant women (p<0.02 and p <0.005, respectively). In summary, second and third trimester pregnancy is associated with a normal circadian TSH rhythm. Elio Roti, Centro per lo Studio, Prevenzione, Diagnosi e Cura delle Tireopatie, University of Parma, via Gramsci 14, 1-43100 Parma, Italy

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.

Urine TRH immunoreactivity in hypothyroid and hyperthyroid patients

1984 ◽  
Vol 105 (4) ◽  
pp. 482-486 ◽  
Author(s):  
Anna-Stina Suhonen ◽  
Juhani Leppäluoto ◽  
Jorma Salmi
Keyword(s):  
Healthy Subjects ◽  
Ammonium Acetate ◽  
Polar Solvent ◽  
Primary Hypothyroidism ◽  
Exchange Chromatography ◽  
Reverse Phase ◽  
Before And After ◽  
Hypothyroid Patients ◽  
Hyperthyroid Patients ◽  
Serum Tsh

Abstract. Urine samples from 8 healthy subjects, from 16 patients with primary hypothyroidism and 8 patients with Graves' hyperthyroidism were pre-purified in SP-Sephadex-C-25 cation-exchange-chromatography, subjected to reverse phase high-pressure liquid chromatography (HPLC) with 0.01 M ammonium acetate pH 4 as a polar and propanol as a non-polar solvent with a 1%/min gradient and assayed in our TRH radioimmunoassay. Urine TRH-immunoreactivity levels were measured before and after 3 months of treatment with thyroxine or methimazole. The urine TRH-levels in healthy subjects were 5.5 ± 1.4 ng/l (mean ± sem, n = 8). In the hypothyroid patients, the urine TRH levels were 50.6 ±40 ng/l before and 71.7 ± 45.3 ng/l after 3 months of treatment with thyroxine. These values did not significantly differ from those in healthy subjects. The large variations were due to highly elevated values in 3 patients. In 2 hypothyroid patients with initially high urine TRH values, 67 and 657 ng/l, urine TRH was measured 5 and 18 months later and was found to have decreased to 5 and 11 ng/l. In the hyperthyroid patients, urine TRH levels were 10.3 ± 3.9 ng/l before and 8.9 ± 3.3 ng/l after the treatment with methimazole and did not differ significantly from the levels in healthy subjects. After 3 months of treatment, the hyper- and the hypothyroid patients were euthyroid. Our results show, that, except in 2 hypothyroid patients, there does not appear to be any relationship between urine TRH levels and serum TSH or thyroid hormone levels in hypothyroid and hyperthyroid patients.

Intra-individual variation of thyroxin, triiodothyronine, and thyrotropin in treated hypothyroid patients: implications for monitoring replacement therapy.

1988 ◽  
Vol 34 (4) ◽  
pp. 696-699 ◽  
Author(s):  
M C Browning ◽  
W M Bennet ◽  
A J Kirkaldy ◽  
R T Jung
Keyword(s):  
Primary Hypothyroidism ◽  
Free Triiodothyronine ◽  
Post Dose ◽  
Strict Adherence ◽  
Mean Values ◽  
Specimen Collection ◽  
Total Triiodothyronine ◽  
The Mean ◽  
Random Fluctuations ◽  
Hypothyroid Patients

Abstract We measured total thyroxin (TT4), free thyroxin (FT4), total triiodothyronine (TT3), free triiodothyronine (FT3), and thyrotropin (TSH) in serum sampled before and 1, 2, 4, 6, and 8 h after administration of prescribed doses of thyroxin to 12 patients with proven primary hypothyroidism. At 2, 4, and 6 h post-dose, the mean values for TT4 and FT4 and also that at 8 h for FT4 significantly (P less than 0.05) exceeded the corresponding pre-dose values. No significant changes were found for TT3, FT3, or TSH. The mean intra-individual CVs over the study period were TT4 4.9%, FT4 5.7%, TT3 8.7%, FT3 8.7%, and TSH 20.2%. Individual subjects showed small but predictable changes in TT4 and FT4. Changes in TT3 and FT3 were greater but random. Fluctuations in TSH were greatest, but in all subjects with detectable concentrations the variations were of similar magnitude. We conclude that strict adherence to timing of specimen collection in relation to dosage is probably unnecessary.

scholarly journals Optimal laboratory testing for diagnosis and monitoring of thyroid nodules, goiter, and thyroid cancer

1996 ◽  
Vol 42 (1) ◽  
pp. 183-187 ◽  
Author(s):  
P W Ladenson
Keyword(s):  
Thyroid Cancer ◽  
Thyroid Carcinoma ◽  
Laboratory Testing ◽  
Thyroid Nodules ◽  
Tumor Burden ◽  
Primary Hypothyroidism ◽  
Thyroid Peroxidase ◽  
Serum Thyroglobulin ◽  
Serum Calcitonin ◽  
Serum Tsh

Abstract Optimal use of laboratory tests to diagnose and monitor patients with goiter, thyroid nodules, or thyroid cancer requires an appreciation of the pathophysiologic factors implicated in thyroid hyperplasia and neoplasia: growth factors (especially thyrotropin, TSH), growth-stimulating immunoglobulins, activating mutations of the TSH receptor, and other oncogenic transformations. In patients with diffuse goiter and thyroid nodules, serum TSH measurement in a highly sensitive assay excludes both primary hypothyroidism and common causes of thyrotoxicosis. In selected patients, screening for anti-thyroid peroxidase with or without anti-thyroglobulin antibodies can confirm the diagnosis of autoimmune thyroiditis. Serum calcitonin measurement is appropriate only when medullary thyroid carcinoma (MTC) is clinically suspected. Laboratory testing is essential in management of thyroid carcinoma patients after primary surgical therapy. Serum TSH measurement is vital to ensure that thyroxine replacement and TSH suppression are adequate in treatment of epithelial cancers. Serial monitoring of serum thyroglobulin (Tg) can detect tumor recurrence and quantify tumor burden. Interpretation of serum Tg results requires an appreciation of certain technical considerations (e.g., anti-Tg antibody interference) and the patient's concurrent TSH status. Periodic serum Tg measurements and 131I scans are complementary monitoring techniques. Serum calcitonin measurement and screening for ret protooncogene mutations are both valuable for identifying individuals with MTC.

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