Thyrotropin, Hyperthyroidism, and Bone Mass

Association of serum thyroid-stimulating hormone and bone mineral density in Chinese adults with normal thyroid function

PURPOSE

This study aims to investigate the association of serum TSH with BMD in Chinese adults with normal thyroid function.

METHODS

These participants were divided into tertiles based on serum TSH levels. Linear regression model and multinomial logistic regression models were used to analyze the associations of continuous BMD and categorical BMD with serum TSH, respectively.

RESULTS

In women younger than 60 years, BMD decreased with the increase of TSH at normal level, while in women older than 60 years, BMD increased with the increase of TSH at normal level; besides, the BMD of women younger than 60 years old was significantly higher than that of women over 60 years old (156.05 ± 39.34 mg/cm3 vs. 86.95 ± 29.51 mg/cm3, P < 0.001). Linear regression results showed negative associations of BMD and normal TSH level in women with age younger than 60 years (β=-4.34, P < 0.001), but this inverse trend was observed in women over 60 years old (β = 2.04, P = 0.041). Both in men younger than 60 years and over 60 years old, BMD decreased with the increase of TSH at normal levels; besides, the BMD of men younger than 60 years was significantly higher than those over 60 years old (143.08 ± 32.76 mg/cm3 vs. 108.13 ± 31.99 mg/cm3, P < 0.001).

CONCLUSIONS

The results demonstrated an opposite trend in BMD at normal TSH levels in younger and elder females, that is, in females younger than 60 years, BMD decreased with the increase of TSH, which indicated that TSH might play a different role in younger and elder females. However, this trend was not significant in males.

Neuroendocrinology of bone

The past decade has witnessed significant advances in our understanding of skeletal homeostasis and the mechanisms that mediate the loss of bone in primary and secondary osteoporosis. Recent breakthroughs have primarily emerged from identifying disease-causing mutations and phenocopying human bone disease in rodents. Notably, using genetically-modified rodent models, disrupting the reciprocal relationship with tropic pituitary hormone and effector hormones, we have learned that pituitary hormones have independent roles in skeletal physiology, beyond their effects exerted through target endocrine glands. The rise of follicle-stimulating hormone (FSH) in the late perimenopause may account, at least in part, for the rapid bone loss when estrogen is normal, while low thyroid-stimulating hormone (TSH) levels may contribute to the bone loss in thyrotoxicosis. Admittedly speculative, suppressed levels of adrenocorticotropic hormone (ACTH) may directly exacerbate bone loss in the setting of glucocorticoid-induced osteoporosis. Furthermore, beyond their established roles in reproduction and lactation, oxytocin and prolactin may affect intergenerational calcium transfer and therefore fetal skeletal mineralization, whereas elevated vasopressin levels in chronic hyponatremic states may increase the risk of bone loss.. Here, we discuss the interaction of each pituitary hormone in relation to its role in bone physiology and pathophysiology.

Dental implant considerations in patients with systemic diseases: An updated comprehensive review

BACKGROUND

Various medical conditions and the drugs used to treat them have been shown to impede or complicate dental implant surgery. It is crucial to carefully monitor the medical status and potential post-operative complications of patients with systemic diseases, particularly elderly patients, to minimize the risk of health complications that may arise.

AIM

The purpose of this study was to review the existing evidence on the viability of dental implants in patients with systemic diseases and to provide practical recommendations to achieve the best possible results in the corresponding patient population.

METHODS

The information for our study was compiled using data from PubMed, Scopus, Web of Science and Google Scholar databases and searched separately for each systemic disease included in our work until October 2023. An additional manual search was also performed to increase the search sensitivity. Only English-language publications were included and assessed according to titles, abstracts and full texts.

RESULTS

In total, 6784 studies were found. After checking for duplicates and full-text availability, screening for the inclusion criteria and manually searching reference lists, 570 articles remained to be considered in this study.

CONCLUSION

In treating patients with systemic conditions, the cost-benefit analysis should consider the patient's quality of life and expected lifespan. The success of dental implants depends heavily on ensuring appropriate maintenance therapy, ideal oral hygiene standards, no smoking and avoiding other risk factors. Indications and contraindications for dental implants in cases of systemic diseases are yet to be more understood; broader and hardcore research needs to be done for a guideline foundation.

Bone-organ axes: bidirectional crosstalk

In addition to its recognized role in providing structural support, bone plays a crucial role in maintaining the functionality and balance of various organs by secreting specific cytokines (also known as osteokines). This reciprocal influence extends to these organs modulating bone homeostasis and development, although this aspect has yet to be systematically reviewed. This review aims to elucidate this bidirectional crosstalk, with a particular focus on the role of osteokines. Additionally, it presents a unique compilation of evidence highlighting the critical function of extracellular vesicles (EVs) within bone-organ axes for the first time. Moreover, it explores the implications of this crosstalk for designing and implementing bone-on-chips and assembloids, underscoring the importance of comprehending these interactions for advancing physiologically relevant in vitro models. Consequently, this review establishes a robust theoretical foundation for preventing, diagnosing, and treating diseases related to the bone-organ axis from the perspective of cytokines, EVs, hormones, and metabolites.

Effects of selenium and iodine on Kashin-Beck disease: an updated review

Kashin-Beck disease (KBD) is an endochondral osteogenesis disorder characterised by epiphysis damage and secondary deformable arthropathy induced by multiple external factors, among which selenium (Se) and iodine deficiency are important influencing factors. Iodine deficiency is usually accompanied by a low Se content in the soil in the KBD areas of China. Se can reverse oxidative damage to chondrocytes. In addition, Se is related to the bone conversion rate and bone mineral density. Low Se will hinder growth and change bone metabolism, resulting in a decrease in the bone conversion rate and bone mineral density. Thyroid hormone imbalance caused by thyroid dysfunction caused by iodine deficiency can damage bone homeostasis. Compared with Se deficiency alone, Se combined with iodine deficiency can reduce the activity of glutathione peroxidase more effectively, which increases the vulnerability of chondrocytes and other target cells to oxidative stress, resulting in chondrocyte death. Clinical studies have shown that supplementation with Se and iodine is helpful for the prevention and treatment of KBD.

Pituitary crosstalk with bone, adipose tissue and brain

Traditional textbook physiology has ascribed unitary functions to hormones from the anterior and posterior pituitary gland, mainly in the regulation of effector hormone secretion from endocrine organs. However, the evolutionary biology of pituitary hormones and their receptors provides evidence for a broad range of functions in vertebrate physiology. Over the past decade, we and others have discovered that thyroid-stimulating hormone, follicle-stimulating hormone, adrenocorticotropic hormone, prolactin, oxytocin and arginine vasopressin act directly on somatic organs, including bone, adipose tissue and liver. New evidence also indicates that pituitary hormone receptors are expressed in brain regions, nuclei and subnuclei. These studies have prompted us to attribute the pathophysiology of certain human diseases, including osteoporosis, obesity and neurodegeneration, at least in part, to changes in pituitary hormone levels. This new information has identified actionable therapeutic targets for drug discovery.

A case of erythrogenic protoporphyria with thyrotoxicosis and liver dysfunction in an adult female

Erythropoietic protoporphyria (EPP) is an inherited metabolic disease caused by the deficiency in ferrochelatase (FECH) encoded by the FECH gene, and it is inherited in an autosomal recessive manner. EPP usually produces acute pain photosensitivity after exposure to sunlight in infancy or early childhood, and liver failure is the most serious associated complication. This article reported an adult female case of EPP complicated with thyrotoxicosis and liver dysfunction which is a rare condition. The patient's liver function improved after liver protection treatment, her thyroid function returned to normal, and her EPP symptoms improved significantly. Moreover, the c.286C>T gene mutation may be the pathogenic locus of EPP. For patients with abnormal liver function, the possibility of EPP should be considered after the common causes are excluded, and FECH gene detection should be done to confirm the diagnosis in time. When EPP is associated with thyrotoxicosis and liver dysfunction, priority may be given to hepatoprotective therapy.

Bone quality in endocrine diseases: determinants and clinical relevance

PURPOSE

Bone is one of the main targets of hormones and endocrine diseases are frequent causes of secondary osteoporosis and fractures in real-world clinical practice. However, diagnosis of skeletal fragility and prediction of fractures in this setting could be a challenge, since the skeletal alterations induced by endocrine disorders are not generally captured by dual-energy X-ray absorptiometry (DXA) measurement of bone mineral density (BMD), that is the gold standard for diagnosis of osteoporosis in the general population. The aim of this paper is to review the existing evidence related to bone quality features in endocrine diseases, proposing assessment with new techniques in the future.

METHODS

A comprehensive search within electronic databases was performed to collect reports of bone quality in primary hyperparathyroidism, hypoparathyroidism, hyperthyroidism, hypercortisolism, growth hormone deficiency, acromegaly, male hypogonadism and diabetes mellitus.

RESULTS

Using invasive and non-invasive techniques, such as high-resolution peripheral quantitative computed tomography or DXA measurement of trabecular bone score (TBS), several studies consistently reported altered bone quality as predominant determinant of fragility fractures in subjects affected by chronic endocrine disorders.

CONCLUSIONS

Assessment of skeletal fragility in endocrine diseases might take advantage from the use of techniques to detect perturbation in bone architecture with the aim of best identifying patients at high risk of fractures.

Bone circuitry and interorgan skeletal crosstalk

The past decade has seen significant advances in our understanding of skeletal homeostasis and the mechanisms that mediate the loss of bone integrity in disease. Recent breakthroughs have arisen mainly from identifying disease-causing mutations and modeling human bone disease in rodents, in essence, highlighting the integrative nature of skeletal physiology. It has become increasingly clear that bone cells, osteoblasts, osteoclasts, and osteocytes, communicate and regulate the fate of each other through RANK/RANKL/OPG, liver X receptors (LXRs), EphirinB2-EphB4 signaling, sphingolipids, and other membrane-associated proteins, such as semaphorins. Mounting evidence also showed that critical developmental pathways, namely, bone morphogenetic protein (BMP), NOTCH, and WNT, interact each other and play an important role in postnatal bone remodeling. The skeleton communicates not only with closely situated organs, such as bone marrow, muscle, and fat, but also with remote vital organs, such as the kidney, liver, and brain. The metabolic effect of bone-derived osteocalcin highlights a possible role of skeleton in energy homeostasis. Furthermore, studies using genetically modified rodent models disrupting the reciprocal relationship with tropic pituitary hormone and effector hormone have unraveled an independent role of pituitary hormone in skeletal remodeling beyond the role of regulating target endocrine glands. The cytokine-mediated skeletal actions and the evidence of local production of certain pituitary hormones by bone marrow-derived cells displays a unique endocrine-immune-skeletal connection. Here, we discuss recently elucidated mechanisms controlling the remodeling of bone, communication of bone cells with cells of other lineages, crosstalk between bone and vital organs, as well as opportunities for treating diseases of the skeleton.

Independent Skeletal Actions of Pituitary Hormones

Over the past years, pituitary hormones and their receptors have been shown to have non-traditional actions that allow them to bypass the hypothalamus-pituitary-effector glands axis. Bone cells-osteoblasts and osteoclasts-express receptors for growth hormone, follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), prolactin, oxytocin, and vasopressin. Independent skeletal actions of pituitary hormones on bone have been studied using genetically modified mice with haploinsufficiency and by activating or inactivating the receptors pharmacologically, without altering systemic effector hormone levels. On another front, the discovery of a TSH variant (TSH-βv) in immune cells in the bone marrow and skeletal action of FSHβ through tumor necrosis factor α provides new insights underscoring the integrated physiology of bone-immune-endocrine axis. Here we discuss the interaction of each pituitary hormone with bone and the potential it holds in understanding bone physiology and as a therapeutic target.

Patients with Thyroid Disorder, a Contraindication for Dental Implants? A Systematic Review

The thyroid gland is composed of the thyroid follicles, considered to be the functional units of the thyroid gland. The synthesis of the thyroid hormones occurs in these follicles. Triiodothyronine (T3) and thyroxine (T4) are the thyroid hormones and affect metabolic processes all through the body. This systematic evaluation was performed to answer the following PICO question: “Can patients with thyroid disorders undergo dental implant rehabilitation with the same survival rate as patients without thyroid disorders?”. A systematic review of the literature was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statements to gather available and current evidence of thyroid disorders and its relationship with dental implants. The electronic search, in the PubMed and Cochrane databases, yielded 22 articles. Out of the 22 articles, only 11 fulfilled the inclusion criteria. Manual research of the reference list yielded no additional papers. According to the SORT criteria and answering our PICO question, level B can be established to conclude that patients with thyroid disorders can be rehabilitated with dental implants, with similar survival rates as patients without thyroid disorders. Papers with higher scientific evidence and bigger sample size should be carried out.

Biofortification: Effect of Iodine Fortified Food in the Healthy Population, Double-Arm Nutritional Study

It is estimated that one-third of the world's population lives in areas where iodine (I) is scarce and its deficiency is responsible for many related disorders, such as goiter, reproductive failure, hearing loss, growth impairment, congenital I deficiency syndrome, and numerous kinds of brain injury. Mineral deficiencies can be overcome via dietary diversification and mineral supplementation. An alternative or even complementary way is represented by the intake of biofortified foods, which can tackle this lack of micronutrients. In this short-term double-arm nutritional intervention study, a cohort of ten people was supplemented with curly endive leaf biofortified with I and ten people with curly endive without biofortification (Intervention Study on Iodine Biofortification Vegetables (Nutri-I-Food - Full-Text View - ClinicalTrials.gov). The effects on whole-body homeostasis and specifically on I, glucose, lipid, and hepatic, iron metabolism was investigated. Blood samples were obtained at baseline and after 12 days of supplementation with curly endive and compared with controls. Hematochemical and urinary parameters were analyzed at baseline and after 12 days. The results showed that short-term I curly endive intervention did not affect the whole body homeostasis in healthy people and revealed an increase in I concentration in urine samples and an increase in vitamin D, calcium, and potassium concentration in blood samples only in the biofortified cohort respect to controls. This study suggests that short-term consumption of I curly endive crops is safe and could positively impact body health.

The Effect of Recombinant Human TSH on Sclerostin and Other Selected Bone Markers in Patients after Total Thyroidectomy for Differentiated Thyroid Cancer

The direct effect of TSH on bone metabolism in vivo is difficult to capture as the changes of its concentrations are followed by respective alterations of thyroid hormone levels. We evaluated the effect of recombinant human TSH (rhTSH) on sclerostin and other bone markers in 29 patients after total thyroidectomy for differentiated thyroid cancer (DTC), without any signs of disease recurrence, who received L-thyroxine, most at non-suppressive doses. For two consecutive days, the patients were administered a standard dose of 0.9 mg rhTSH, i.m. Concentrations of sclerostin, osteocalcin, β-CrossLaps, PTH, and some other parameters, were measured before and five days after the first rhTSH administration. The greater the increase in TSH concentration (∆TSH), the greater the decrease in: ∆sclerostin (r = -0.672; p < 0.001), ∆β-CrossLaps (r = -0.580; p < 0.001) and ∆osteocalcin (r = -0.405; p = 0.029) levels, were recorded. The degree of TSH increase depended on the baseline PTH (r = 0.651; p < 0.001), age, and creatinine concentrations. rhTSH strongly inhibited bone turnover, thus, TSH-independently of thyroid hormones-exerted a direct protective effect on bone metabolism. Baseline PTH affected the magnitude of TSH increase and the degree of lowering in sclerostin and β-CrossLaps that suggest factors affecting PTH may play a role in the effect of TSH on the bone.