Hypothyroidism associated with parathyroid disorders

Hypothyroidism-Etiologies, Evaluation, and Emergency Care

Thyroid hormone affects every human organ system and is a vital component of metabolism. Common and easily treatable, hypothyroidism does not usually require emergency management. However, myxedema coma is the decompensated form of hypothyroidism and can be life threatening if not treated expediently.

An Overview on Different L-Thyroxine (l-T4) Formulations and Factors Potentially Influencing the Treatment of Congenital Hypothyroidism During the First 3 Years of Life

Congenital hypothyroidism (CH) is a relatively frequent congenital endocrine disorder, caused by defective production of thyroid hormones (THs) at birth. Because THs are essential for the development of normal neuronal networks, CH is also a common preventable cause of irreversible intellectual disability (ID) in children. Prolonged hypothyroidism, particularly during the THs-dependent processes of brain development in the first years of life, due to delays in diagnosis, inadequate timing and dosing of levothyroxine (l-thyroxine or l-T₄), the non-compliance of families, incorrect follow-up and the interference of foods, drugs and medications affecting the absorption of l-T₄, may be responsible for more severe ID. In this review we evaluate the main factors influencing levels of THs and the absorption of l-T₄ in order to provide a practical guide, based on the existing literature, to allow optimal follow-up for these patients.

Pentabromoethylbenzene Exposure Induces Transcriptome Aberration and Thyroid Dysfunction: In Vitro, in Silico, and in Vivo Investigations

Pentabromoethylbenzene (PBEB), as one of the novel brominated flame retardants (NFBRs), has caused increasing public concern for health risks. Till now, information regarding potential effects of PBEB on thyroid function remains unclear. Herein, we investigated thyroid disruption of PBEB in vitro and in silico and evaluated thyroid dysfunction induced by PBEB using Sprague-Dawley rats. PBEB showed thyroid receptor (TR) β antagonistic activity with IC₅₀ of 9.82 × 10^-7 M in the dual-luciferase reporter gene assay and induced relative reorientation of helix 11 (H11) and H12 of the TR ligand binding domain as revealed by molecular dynamics simulations. PBEB (0.2, 2, 20 mg/kg BW/d) markedly altered the transcriptome profile of thyroid with induction of 17, 42, and 119 differentially expressed genes (DEGs) involved in thyroid hormone signaling and synthesis pathway, of which transthyretin and albumin are common DEGs. The 28-d exposure to PBEB significantly decreased the triiodothyronine level (from 7.23 to 5.67 ng/mL) and increased the thyrotropin level (from 7.88 to 12.86 mU/L) for female rats. PBEB consequently reduced thyroid weight and altered its morphology with more depleted follicles. Overall, our study provides the first account of evidence on PBEB exerted thyroid disruption, transcriptome aberration, and morphological alteration, facilitating health risk assessment of PBEB and structurally related NBFRs.

Physical Activity-Dependent Regulation of Parathyroid Hormone and Calcium-Phosphorous Metabolism

Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the effects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise. Altered PTH metabolism underlies hyperparathyroidism and hypoparathyroidism, the complications of which affect the organs involved in calcium and phosphorous metabolism (bone and kidney) and other body systems as well. Exercise affects PTH expression and secretion by altering the circulating levels of calcium and phosphate. In turn, PTH responds directly to exercise and exercise-induced myokines. Here, we review the main concepts of the regulation of PTH expression and secretion under physiological conditions, in acute and chronic exercise, and in relation to PTH-related disorders.

The effects of patient and disease-related factors on the quality of life in patients with hypoparathyroidism

This study aims to evaluate factors affecting the quality of life (QOL) of hypoparathyroidism. While QOL is reduced in post-surgical and non-surgical groups, mental health seems to be less affected in non-surgical patients. Having an additional disease affects QOL negatively but having thyroid cancer may not change the QOL results.

PURPOSE

Hypoparathyroidism (HypoPT) is an orphan disease, which causes physical, emotional, and cognitive problems. We aimed to estimate the factors affecting the quality of life (QOL) of HypoPT patients.

METHODS

Basal characteristics, treatments, and laboratory results of the participants were recorded. QOL of the patients and controls were evaluated via the Short Form-36 (SF-36) survey.

RESULTS

One hundred sixty HypoPT patients were compared with 148 controls. Patients had lower scores in all SF-36 domains than controls. Non-surgical patients had better scores in vitality and mental health compared with post-surgical ones. Males had higher scores in mental and physical health domains than females. Non-surgical patients had higher scores in mental health compared with post-surgical ones when calcium levels were between 8 and 8.9 mg/dL. When we compared the patients with the pathological results, QOL scores of post-surgical patients with thyroid cancer were not different from the patients with thyroid nodular hyperplasia. HypoPT patients having an additional disease presented lower scores in physical functions and general health. Disease duration was found out positively correlated with vitality in non-surgical patients.

CONCLUSION

While QOL is reduced in both post-surgical and non-surgical HypoPT groups, mental health seems to be less affected in non-surgical patients. Non-surgical patients might be tolerating hypocalcemia symptoms, lower calcium levels, and longer disease duration better than post-surgical ones. Having an additional disease affects the QOL negatively but having thyroid cancer may not change the QOL results of post-surgical patients.

Molecular defects in thyroid dysgenesis

Congenital hypothyroidism (CH) is a neonatal endocrine disorder that might occur as itself or be associated to congenital extra-thyroidal defects. About 85% of affected subjects experience thyroid dysgenesis (TD), characterized by defect in thyroid gland development. In vivo experiments on null mice paved the way for the identification of genes involved thyroid morphogenesis and development, whose mutation has been strongly associated to TD. Most of them are thyroid-specific transcription factors expressed during early thyroid development. Despite the arduous effort in unraveling the genetics of TD in animal models, up to now these data have been discontinuously confirmed in humans and only 5% of TD have associated with known null mice-related mutations (mainly PAX8 and TSHR). Notwithstanding, the advance in genetic testing represented by the next-generation sequencing (NGS) approach is steadily increasing the list of genes whose highly penetrant mutation predisposes to TD. In this review we intend to outline the molecular bases of TD, summarizing the current knowledge on thyroid development in both mice and humans and delineating the genetic features of its monogenetic forms. We will also highlight current strategies to enhance the insight into the non-Mendelian mechanisms of abnormal thyroid development.

Genetics and management of congenital hypothyroidism

Several evidences support a relevant genetic origin for Congenital Hypothyroidism (CH), however familial forms are uncommon. CH can be due to morphogenetic or functional defects and several genes have been originally associated either with thyroid dysgenesis or dyshormonogenesis, with a highly variable expressivity and a frequently incomplete penetrance of the genetic defects. The phenotype-driven genetic analyses rarely yielded positive results in more than 10% of cases, thus raising doubts on the genetic origin of CH. However, more recent unsupervised approaches with systematic Next Generation Sequencing (NGS) analysis revealed the existence of hypomorphic alleles of these candidate genes whose combination can explain a significant portion of CH cases. The co-segregation studies of the hypothyroid phenotype with multiple gene variants in pedigrees confirmed the potential oligogenic origin of CH, which finally represents a suitable explanation for the frequent sporadic occurrence of this disease.