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Related Concept Videos

Hyperthyroidism I: Introduction01:25

Hyperthyroidism I: Introduction

Hyperthyroidism is a type of thyrotoxicosis characterized by the thyroid gland's overproduction of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). This hormone excess increases the basal metabolic rate and enhances sensitivity to catecholamines.DiagnosisDiagnosis is based on clinical features and biochemical testing. It typically shows suppressed thyroid-stimulating hormone (TSH) levels below 0.4 mIU/L, with elevated free T3 and/or T4. Additional tests, including thyroid...
Synthesis and Regulation of Thyroid Hormones01:20

Synthesis and Regulation of Thyroid Hormones

Low blood levels of the thyroid hormones — triiodothyronine (T3) and thyroxine (T4) — signal the hypothalamus to release the thyrotropin-releasing hormone (TRH). TRH then reaches the pituitary gland and stimulates the release of thyroid-stimulating hormone(TSH) into the bloodstream.
Upon reaching the thyroid gland, TSH stimulates the follicular cells' active uptake of iodide ions from the blood. The ions diffuse to the apical surface of the cells and are oxidized to iodine. The iodine is then...
Hypothyroidism II: Pathophysiology01:23

Hypothyroidism II: Pathophysiology

Hypothyroidism is a disorder characterized by insufficient production of thyroid hormones, which regulate metabolism, energy balance, and multiple organ systems.TypesHypothyroidism is classified based on the level of dysfunction. Primary hypothyroidism results from intrinsic thyroid gland dysfunction, causing reduced hormone production despite normal or increased stimulation. Secondary hypothyroidism arises from inadequate thyroid-stimulating hormone (TSH) secretion by the pituitary. Tertiary...
Hyperthyroidism II: Pathophysiology01:27

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Hyperthyroidism is a hypermetabolic state caused by elevated levels of thyroid hormones, triiodothyronine (T3) and thyroxine (T4). It results from dysregulation at the thyroid, pituitary, or immune system level and affects multiple organ systems.PathophysiologyThe most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder in which antibodies, specifically thyroid-stimulating antibodies (TSAb), a subtype of TSH receptor antibodies (TRAb), bind to and activate TSH receptors...
Therapeutic Drug Monitoring: Drug Analysis Methods01:26

Therapeutic Drug Monitoring: Drug Analysis Methods

Therapeutic Drug Monitoring (TDM) is a clinical practice that measures specific drug levels in a patient's blood or body tissues to tailor drug therapy effectively. This monitoring is critical for managing drugs with narrow therapeutic indices like digoxin and phenytoin, ensuring they are both safe and effective. For instance, monitoring theophylline levels in asthma patients involves precision and sensitivity to adjust doses according to individual responses to therapy, ensuring efficacy and...
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The thyroid hormone (TH) plays a pivotal role in the intricate orchestration of physiological processes, exerting profound effects on development, metabolism, and homeostasis throughout different life stages.
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Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model
04:39

Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model

Published on: March 17, 2023

Accuracy issues in free thyroxine testing methods.

Jerald C Nelson1, Elliot W Yoo, R Bruce Wilcox

  • 1Loma Linda University School of Medicine, Loma Linda, CA, USA.

Seminars in Perinatology
|November 15, 2008
PubMed
Summary
This summary is machine-generated.

Neonatal free thyroxine (T4) assay results vary by method. Analog-based assays can yield inaccurate free thyroxine (T4) measurements due to protein binding, impacting clinical interpretation.

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Area of Science:

  • Endocrinology
  • Clinical Chemistry
  • Neonatal Medicine

Background:

  • Assay methodology significantly influences the incidence of low neonatal free thyroxine (T4) results.
  • Understanding the behavior of free thyroxine (T4) assays in the presence of binding proteins is crucial for accurate neonatal assessment.

Purpose of the Study:

  • To investigate the impact of different binding proteins on free thyroxine (T4) assay results.
  • To evaluate the accuracy of analog-based free T4 assays in representing actual free T4 concentrations under various conditions.

Main Methods:

  • Comparison of nonanalog and analog-based free T4 assay results.
  • Assessment of free T4 concentrations with and without the addition of albumin, transthyretin, and thyroxine-binding globulin.
  • Evaluation of assay specificity for free T4 versus bound T4 forms.

Main Results:

  • Analog-based free T4 assays produced similar results across a wide range of free T4 concentrations.
  • Albumin and transthyretin increased analog-based free T4 assay results, despite decreasing free T4 concentrations.
  • Thyroxine-binding globulin decreased both free T4 concentrations and assay results, with some results not reflecting actual concentrations.
  • Some assays lacked specificity for free T4 over bound T4 forms.

Conclusions:

  • The protein binding T4 significantly affects total T4 assay results, particularly those used in free T4 index calculations.
  • Methodology-dependent variations in neonatal free T4 assays necessitate careful interpretation.
  • Analog-based free T4 assays may not accurately reflect free T4 concentrations in the presence of certain binding proteins.