scholarly journals USE OF THE FREE THYROXINE INDEX TO REFINE THE LOWER LIMIT OF A FREE THYROXINE IMMUNOASSAY FOR DETECTION OF SECONDARY HYPOTHYROIDISM

2020 ◽  
Author(s):  
Gregory P. Westcott ◽  
Christopher M. Mulla ◽  
James V. Hennessey
Keyword(s):  
Lower Limit ◽  
Medical Center ◽  
Area Under The Curve ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Imaging Data ◽  
Free T4 ◽  
Secondary Hypothyroidism ◽  
Free Thyroxine Index ◽  
Stimulating Hormone

Objective: To determine the utility of measuring free T4 index (FT4I) in patients with low free T4 (FT4) by immunoassay and normal TSH in the evaluation for secondary hypothyroidism. Methods: We performed a retrospective medical chart review of patients seen at a single institution as outpatients who had a simultaneously normal TSH, low FT4, and any FT4I measured between June 2014 and October 2016. Demographic, laboratory, and imaging data were collected. Using FT4I level as the reference for diagnosis of hypothyroidism, the sensitivity and specificity of FT4 immunoassay lower limit thresholds were determined. Within each threshold group, available brain imaging and biochemical evaluation was categorized according to presence or absence of pituitary disease. Results: A total of 155 sets of result pairs (FT4 and FT4I) performed on 118 subjects were analyzed. The lower limit of normal FT4 by immunoassay at this institution is 0.93 ng/dL, though all pairs with FT4 ≥ 0.89 ng/dL had a normal FT4I. All pairs with FT4 ≤ 0.67 ng/dL had a low FT4I. No pituitary macroadenomas were identified in any subjects, though rates of pituitary imaging in this patient sample were low. Conclusions: Patients with a borderline low FT4 by immunoassay often have a normal FT4I. In such patients at our center, significant structural and biochemical pituitary pathology was uncommon. Abbreviations: ACTH = adrenocorticotropic hormone; AUC = area under the curve; BIDMC = Beth Israel Deaconess Medical Center; FSH = follicle-stimulating hormone; FT4 = free thyroxine; FT4I = free thyroxine index; IGF-1 = insulin-like growth factor 1; LH = luteinizing hormone; PPV = positive predictive value; ROC = receiver operating characteristic; SD = standard deviation; TSH = thyroid stimulating hormone.

scholarly journals In primary care, is measuring free-thyroxine plus thyroid-stimulating hormone to detect hypopituitarism cost-effective? A cost utility analysis using Markov chain models

BMJ Open ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. e029369 ◽  
Author(s):  
Brian Shine ◽  
Tim James ◽  
Amanda Adler
Keyword(s):  
Primary Care ◽  
Model Simulation ◽  
Cost Effective ◽  
Cost Utility ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Thyroid Function Tests ◽  
Life Years ◽  
Secondary Hypothyroidism ◽  
Stimulating Hormone

ObjectiveWe examined whether it is cost-effective to measure free thyroxine (FT4) in addition to thyrotropin (thyroid-stimulating hormone (TSH)) on all requests for thyroid function tests from primary care on adult patients.BackgroundHypopituitarism occurs in about 4 people per 100 000 per year. Loss of thyrotropin (TSH) secretion may lead to secondary hypothyroidism with a low TSH and low FT4, and this pattern may help to diagnose hypopituitarism that might otherwise be missed.DesignMarkov model simulation.Primary outcome measureIncremental cost-effectiveness ratio (ICER), the ratio of cost in pounds to benefit in quality-adjusted life years of this strategy.ResultsThe ICER for this strategy was £71 437. Factors with a large influence on the ICER were the utilities of the treated hypopituitary state, the likelihood of going to the general practitioner (GP) and of the GP recognising a hypopituitary patient. The ICER would be below £20 000 at a cost to the user of an FT4 measurement of £0.61.ConclusionWith FT4 measurements at their present cost to the user, routine inclusion of FT4 in a thyroid hormone profile is not cost-effective.

Establishment of Early Pregnancy Related Thyroid Hormone Models and Reference Intervals for Pregnant Women in China Based on Real World Data

2021 ◽  
Vol 53 (04) ◽  
pp. 272-279
Author(s):  
Chaochao Ma ◽  
Xiaoqi Li ◽  
Lixin Liu ◽  
Xinqi Cheng ◽  
Fang Xue ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Pregnant Women ◽  
Early Pregnancy ◽  
Gestational Age ◽  
Dynamic Change ◽  
Reference Intervals ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Stimulating Hormone

AbstractThyroid hormone reference intervals are crucial for diagnosing and monitoring thyroid dysfunction during early pregnancy, and the dynamic change trend of thyroid hormones during pregnancy can assist clinicians to assess the thyroid function of pregnant women. This study aims to establish early pregnancy related thyroid hormones models and reference intervals for pregnant women. We established two derived databases: derived database* and derived database#. Reference individuals in database* were used to establish gestational age-specific reference intervals for thyroid hormones and early pregnancy related thyroid hormones models for pregnant women. Individuals in database# were apparently healthy non-pregnant women. The thyroid hormones levels of individuals in database# were compared with that of individuals in database* using nonparametric methods and the comparative confidence interval method. The differences in thyroid stimulating hormone and free thyroxine between early pregnant and non-pregnant women were statistically significant (p<0.0001). The reference intervals of thyroid stimulating hormone, free thyroxine and free triiodothyronine for early pregnant women were 0.052–3.393 μIU/ml, 1.01–1.54 ng/dl, and 2.51–3.66 pg/ml, respectively. Results concerning thyroid stimulating hormone and free thyroxine reference intervals of early pregnancy are comparable with those from other studies using the same detection platform. Early pregnancy related thyroid hormones models showed various change patterns with gestational age for thyroid hormones. Early pregnancy related thyroid hormones models and reference intervals for pregnant women were established, so as to provide accurate and reliable reference basis for the diagnosing and monitoring of maternal thyroid disfunction in early pregnancy.

Method specific second-trimester reference intervals for thyroid-stimulating hormone and free thyroxine

2009 ◽  
Vol 42 (7-8) ◽  
pp. 750-753 ◽  
Author(s):  
Rechelle Silvio ◽  
Karly J. Swapp ◽  
Sonia L. La'ulu ◽  
Kara Hansen-Suchy ◽  
William L. Roberts
Keyword(s):  
Reference Intervals ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Second Trimester ◽  
Stimulating Hormone

Preterm to term infant postmenstrual age reference intervals for thyroid-stimulating hormone and free thyroxine

2021 ◽  
Author(s):  
George M. Ziegler ◽  
Jonathan L. Slaughter ◽  
Monika Chaudhari ◽  
Herveen Singh ◽  
Pablo J. Sánchez ◽  
...  
Keyword(s):  
Reference Intervals ◽  
Thyroid Stimulating Hormone ◽  
Term Infant ◽  
Free Thyroxine ◽  
Postmenstrual Age ◽  
Stimulating Hormone

Subclinical Hyperthyroidism: Diagnostic Criteria and Principles of Treatment

2016 ◽  
pp. 75-79
Author(s):  
Vita Galitskaya
Keyword(s):  
Hormone Receptors ◽  
Color Doppler ◽  
Specific Treatment ◽  
Nodular Goiter ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Subclinical Hyperthyroidism ◽  
Mineral Density ◽  
Free Triiodothyronine ◽  
Stimulating Hormone

This article presents the European Thyroid Association guidelines for diagnosis and treatment of subclinical hyperthyroidism, 2015. Determination of thyroid1stimulating hormone levels can help to diagnose a variety of pathological conditions: hypertension, cardiac fibrillation, atrial fibrillation, mineral density reduction in bones, menstrual irregularities, infertility, which require specific treatment after detection of hormonal status disorders (subclinical, overt), taking into account the patient’s age. Diagnosis of endogenous subclinical hyperthyroidism is based solely on the results of laboratory tests, not clinical criteria. Endogenous subclinical hyperthyroidism is defined by the presence of sub-normal levels of thyroid-stimulating hormone with normal levels of free thyroxine, total triiodothyronine, and/or free triiodothyronine. There are two categories of endogenous subclinical hyperthyroidism: stage 1 – the level of thyroid-stimulating hormone is 0,1–0,39 mIU/l; stage 2 – the level of thyroid-stimulating hormone is <0.1 mIU/l. The levels of free thyroxine and free triiodothyronine, as a rule, are medium-high value at a subclinical level of thyroid hormone and can help differentiate between endogenous subclinical hyperthyroidism from overt hyperthyroidism. It is recommended to study the thyroid-stimulating hormone level as the first test for the diagnosis of subclinical hyperthyroidism. In identifying low levels of thyroid-stimulating hormone it is necessary to investigate the level of free thyroxine, free or bound triiodothyronine. Patients with primary sub-normal levels of thyroid-stimulating hormone with concentration of thyroid hormones in the upper limit or in normal range should be evaluated within 2-3 months. It is recommended to perform scintigraphy and possible 24-hour test the absorption of radioactive iodine if in patient with 2nd degree endogenous subclinical hyperthyroidism there is nodular goiter to determine treatment strategy. Ultrasonography with color Doppler can be informative for patients with endogenous subclinical hyperthyroidism and nodular goiter. Determining the level of antibodies to thyroid-stimulating hormone receptors can confirm the etiology of autoimmune-induced hyperthyroidism.

Genetic thyroid stimulating hormone regulation of atrial fibrillation risk is mediated through an effect on height

2021 ◽  
Author(s):  
Mingjian Shi ◽  
Ali M Manouchehri ◽  
Christian M Shaffer ◽  
Nataraja Sarma Vaitinadin ◽  
Jacklyn N Hellwege ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Genetic Association ◽  
Multiple Testing ◽  
Mendelian Randomization ◽  
Later Life ◽  
Thyroid Stimulating Hormone ◽  
Hormone Regulation ◽  
Nucleotide Polymorphisms ◽  
Free T4 ◽  
Stimulating Hormone

Abstract Background A genetic predisposition to lower thyroid stimulating hormone (TSH) levels associates with increased atrial fibrillation (AF) risk through undefined mechanisms. Defining the genetic mediating mechanisms could lead to improved targeted therapies to mitigate AF risk. Methods We used two-sample Mendelian randomization (MR) to test associations between TSH-associated single nucleotide polymorphisms (SNPs) and 16 candidate mediators. We then performed multivariable Mendelian randomization (MVMR) to test for a significant attenuation of the genetic association between TSH and AF, after adjusting for each mediator significantly associated with TSH. Results Four candidate mediators (free T4, systolic blood pressure, heart rate, and height) were significantly inversely associated with genetically predicted TSH after adjusting for multiple testing. In MVMR analyses, adjusting for height significantly decreased the magnitude of the association between TSH and AF from -0.12 (s.e. 0.02) occurrences of AF per standard deviation change in height to -0.06 (0.02) (p=0.005). Adjusting for the other candidate mediators did not significantly attenuate the association. Conclusions The genetic association between TSH and increased AF risk is mediated, in part, by taller stature. Thus, some genetic mechanisms underlying TSH variability may contribute to AF risk through mechanisms determining height occurring early in life that differ from those driven by thyroid hormone level elevations in later life.

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.

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