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Related Concept Videos

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...
Functions of Thyroid Hormones01:18

Functions of Thyroid Hormones

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.
TH is indispensable for the normal development and maturation of the skeletal, muscular, and nervous systems during fetal and childhood growth. It facilitates bone mineral turnover and regulates protein synthesis in developing tissues, contributing significantly to overall growth and...
Hyperthyroidism II: Pathophysiology01:27

Hyperthyroidism II: Pathophysiology

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...
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 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...
Mitral Stenosis I: Introduction01:22

Mitral Stenosis I: Introduction

Mitral Valve Stenosis (MVS) is a heart condition where the mitral valve narrows, impeding blood circulation from the left atrium to the left ventricle. The etiology and pathophysiology of this condition are multifaceted, leading to a cascade of cardiovascular complications.Causes of Mitral Valve StenosisRheumatic Heart Disease: It is the main cause of mitral valve stenosis, particularly in developing nations. This condition arises from rheumatic fever, an inflammatory illness resulting from...

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Related Experiment Video

Updated: Jul 14, 2026

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice
08:21

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Published on: June 15, 2020

Thyroid stimulating hormone and left ventricular function.

Amjid Iqbal1, Henrik Schirmer, Per Lunde

  • 1Department of Cardiology, University Hospital of North Norway, 9038 Tromsø, Norway. amjid.iqbal@unn.no

The Journal of Clinical Endocrinology and Metabolism
|June 15, 2007
PubMed
Summary

Subclinical thyroid dysfunction, specifically low thyroid-stimulating hormone (TSH) levels, may affect myocardial velocities. However, subclinical hypothyroidism does not appear to impact cardiac function or left ventricular mass.

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Echocardiographic Assessment of Cardiac Anatomy and Function in Adult Rats
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Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice
08:21

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Published on: June 15, 2020

Echocardiographic Assessment of Cardiac Anatomy and Function in Adult Rats
08:09

Echocardiographic Assessment of Cardiac Anatomy and Function in Adult Rats

Published on: December 13, 2019

Area of Science:

  • Cardiology
  • Endocrinology
  • Thyroidology

Background:

  • Overt thyroid dysfunction is linked to cardiac disease, but the relationship with subclinical thyroid dysfunction is less clear.
  • Understanding the cardiac implications of subclinical thyroid dysfunction is crucial for comprehensive patient care.

Purpose of the Study:

  • To investigate the association between serum TSH levels and cardiac function.
  • To determine if subclinical thyroid dysfunction influences left ventricular mass and function.

Main Methods:

  • Cross-sectional epidemiological and nested case-control studies were conducted.
  • Echocardiography, including conventional and pulsed-wave tissue Doppler (PWTD), assessed cardiac function.
  • Left ventricular mass index (LVMI) and myocardial velocities were measured in subjects with varying TSH levels and normal free T4/T3.

Main Results:

  • No significant correlation was observed between serum TSH levels and LVMI.
  • Subjects with subclinical hypothyroidism (TSH 3.50-10.0 mIU/liter) showed no signs of cardiac dysfunction.
  • Individuals with low TSH (<0.50 mIU/liter) exhibited increased myocardial velocities on PWTD compared to euthyroid controls.

Conclusions:

  • Serum TSH levels are not significantly associated with LVMI, except possibly in overt thyroid disease.
  • Subclinical hypothyroidism (mildly elevated TSH) appears to be associated with normal cardiac function.
  • Lower TSH levels (<0.50 mIU/liter) are linked to detectable changes in myocardial velocities, suggesting potential subclinical cardiac effects.