Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Synthesis and Regulation of Thyroid Hormones

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...

Hyperthyroidism I: Introduction

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...

Hypothyroidism II: Pathophysiology

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: Pathophysiology

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...

Graves Disease II: Pathophysiology

Graves Disease II: Pathophysiology

Graves’ disease is an autoimmune disorder characterized by the production of thyroid-stimulating immunoglobulins (TSI) that activate TSH receptors, leading to excessive synthesis and release of thyroid hormones (T3 and T4) and resulting in hyperthyroidism.Among all causes of hyperthyroidism, Graves’ disease is the most common and can happen at any age, though it is more frequent in women. It produces a hypermetabolic state with features such as weight loss, tachycardia, tremor, and heat...

Goiter

Goiter

Goiter refers to an abnormal enlargement of the thyroid gland that may appear as a diffuse goiter (uniform enlargement) or nodular (single or multiple nodules). Functionally, it is classified as nontoxic (normal/low hormone levels) or toxic (excess hormone production).PathophysiologyDiffuse thyroid enlargement typically results from prolonged stimulation by thyroid-stimulating hormone (TSH) or TSH-like agents, commonly seen in hypothyroidism or iodine deficiency. In contrast, in hyperthyroid...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

The genotypic and phenotypic landscape of PDHA1-related pyruvate dehydrogenase complex deficiency.

Brain : a journal of neurology·2025

Same author

Expanding the Phenotypic Spectrum of Methylenetetrahydrofolate Reductase (MTHFR) Deficiency in Childhood: A Case Series.

Clinical case reports·2025

Same author

Hepatic Phenotype in NBAS-Associated Disease: Clinical Course, Prognostic Factors and Outcome in 230 Patients.

Liver international : official journal of the International Association for the Study of the Liver·2025

Same author

Glycerol intoxication syndrome in young children, following the consumption of slush ice drinks.

Archives of disease in childhood·2025

Same author

Catalogue of inherited autosomal recessive disorders found amongst the Roma population of Europe.

European journal of medical genetics·2024

Same author

MRI in LARS1 deficiency-Spectrum, patterns, and correlation with acute neurological deterioration.

Journal of inherited metabolic disease·2024

Search research articles

Related Experiment Video

Updated: Jun 18, 2026

Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model

Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model

Published on: March 17, 2023

Elevated TSH levels in a mentally retarded boy.

Ellen Crushell¹, William Reardon

¹National Centre for Inherited Metabolic Disorders, Children's University Hospital and Our Lady's Children's Hospital, Dublin, Ireland.

European Journal of Pediatrics

|November 26, 2009

Summary

This summary is machine-generated.

Allan-Herndon-Dudley syndrome (AHDS) is caused by MCT8 gene mutations. Elevated T3 levels, despite hypothyroidism diagnosis, can indicate AHDS in infants with developmental delays.

More Related Videos

A Versatile, Behavioral Method to Investigate Thyroid Hormone Effects on Cerebellar Function

A Versatile, Behavioral Method to Investigate Thyroid Hormone Effects on Cerebellar Function

Published on: October 6, 2023

Related Experiment Videos

Last Updated: Jun 18, 2026

Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model

Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model

Published on: March 17, 2023

A Versatile, Behavioral Method to Investigate Thyroid Hormone Effects on Cerebellar Function

A Versatile, Behavioral Method to Investigate Thyroid Hormone Effects on Cerebellar Function

Published on: October 6, 2023

Area of Science:

Genetics
Endocrinology
Neurodevelopmental Disorders

Background:

Allan-Herndon-Dudley syndrome (AHDS) is an X-linked disorder characterized by intellectual disability and hypotonia.
Mutations in the monocarboxylate transporter 8 (MCT8) gene, also known as SLC16A2, are the underlying cause of AHDS.
MCT8 is crucial for thyroid hormone transport into cells.

Observation:

A 23-month-old boy presented with severe developmental delay, hypotonia, recurrent emesis, and irritability.
He was diagnosed with hypothyroidism at 4 months of age, but triiodothyronine (T3) levels were paradoxically elevated.
These clinical features and laboratory findings prompted molecular investigation.

Findings:

Molecular analysis identified a single base duplication (c.1614dupC) in exon 5 of the MCT8 gene.
This genetic mutation, leading to a frameshift (p.Ile539fs), is consistent with a diagnosis of AHDS.
The findings confirm MCT8 gene mutations as the cause of the patient's condition.

Implications:

Triiodothyronine (T3) levels are a key diagnostic marker for AHDS, even in the presence of hypothyroidism.
Elevated thyroid-stimulating hormone (TSH) levels should also raise suspicion for AHDS.
Early and accurate diagnosis of AHDS is essential for appropriate management and genetic counseling.