Association of subclinical thyroid dysfunction with bone mineral density and fracture: a meta-analysis of prospective cohort studies

New Insights in the Pathophysiology, Epidemiology, and Response to Treatment of Osteoporotic Vertebral Fractures

CONTEXT

Vertebral fractures (VFs) make up an important but challenging group of fractures often caused by osteoporosis. Osteoporotic fractures pose unique diagnostic challenges in generally requiring imaging for diagnosis. The objective of this narrative mini-review is to provide an overview of these recent advances in our knowledge of VF pathophysiology and epidemiology with particular focus on endocrine diseases, prevention, and treatment.

EVIDENCE ACQUISITION

We searched PubMed on May 23, 2022, for studies of VFs in humans. Results were limited to papers available as full-text publications in English, published from 2020 and onward. This yielded 3457 citations. This was supplemented by earlier publications selected to add context to the recent findings.

EVIDENCE SYNTHESIS

Studies addressed VF risk in hyperthyreosis, hyperparathyroidism, acromegaly, Cushing syndrome, primary aldosteronism, and diabetes. For pharmaceutical treatment, new studies or analyses were identified for romosozumab and for weekly teriparatide. Several studies, including studies in the immediate pipeline, were intervention studies with vertebroplasty or kyphoplasty, including combination with stem cells or pharmaceuticals.

CONCLUSIONS

Endocrinologists should be aware of the high likelihood of osteoporotic VFs in patients with endocrine diseases. Though licensed treatments are able to substantially reduce the occurrence of VFs in patients with osteoporosis, the vast majority of recent or ongoing randomized controlled trials in the VF area focus on advanced invasive therapy of the fracture itself.

The relationship of hip fracture and thyroid disorders: a systematic review

Introduction

Bone density regulation is considered one of the systems affected by thyroid hormones, leading to low bone density that can result in pathologic fractures, including hip fractures. This review aimed to update clinicians and researchers about the current data regarding the relationship between hip fractures and thyroid disorders.

Methods

English papers were thoroughly searched in four main online databases of Scopus, Web of Science, PubMed, and Embase. Data extraction was done following two steps of screening/selection using distinct inclusion/exclusion criteria. This study used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) checklist and the Newcastle-Ottawa Scale (NOS) as bias assessment.

Results

In total, 19 articles were included in the research. The risk of hip fractures in women with differentiated thyroid cancer (DTC) is higher than hip fractures caused by osteoporosis. Men with hyperthyroidism and subclinical hyperthyroidism are at higher risk for hip fracture. Also, a decrease in serum thyroid stimulating hormone (TSH) may be associated with an increased risk of hip fracture.

Conclusion

Reaching a consensus conclusion regarding the association between subclinical thyroid dysfunction and hip fracture is not feasible due to the heterogenicity of evidence; however, there may be a higher risk of fracture in individuals with subclinical hyperthyroidism.

Long-term thionamide antithyroid treatment of Graves' disease

Thionamide antithyroid drugs (ATD) are the treatment of choice for Graves' hyperthyroidism. The major drawback of ATD treatment for 1-2 years is the relapse of hyperthyroidism in about 50% of patients. Recently, it has been shown that ATD treatment for more than five years is accompanied by long-term remission in majority of patients without additional major side effects in both adults and children. Compared to radioactive iodine therapy, long-term ATD results in more favorable outcomes. This review summarizes the evidence on long-term ATD therapy regarding the remission rate of hyperthyroidism, efficacy and safety, indications and mode of therapy in patients with hyperthyroidism.

Subclinical hypothyroidism, outcomes and management guidelines: a narrative review and update of recent literature

Subclinical hypothyroidism (SCH) is diagnosed when serum thyroid stimulation hormone (thyrotropin; TSH) levels are above the reference range, accompanied by levels of free thyroxine within its reference range. The management of SCH remains a diagnostic and therapeutic challenge despite many years of research relating to its epidemiology, aetiology, effectiveness of treatment and safety. European Thyroid Association (ETA) guidelines for the management of SCH were published almost a decade ago. This narrative review summarizes the clinical literature relating to SCH and outcomes since the publication of these guidelines. Clinical evidence emerging during the previous decade generally supports the view that SCH is associated with adverse outcomes to an extent that is intermediate between euthyroidism and overt hypothyroidism although evidence that treatment with thyroid hormone replacement is beneficial is lacking. Accordingly, the rationale for the recommendations for intervention in the ETA guidelines based on the age of the patient, level of serum TSH, symptoms and comorbidities remains valid today.

Update on subclinical thyroid dysfunction

Subclinical thyroid dysfunction is defined by serum thyroid-stimulating hormone (TSH) levels either greater or less than the reference range with normal thyroxine (T4) concentrations, and consists of subclinical hypothyroidism (SCH) and subclinical hyperthyroidism (SCHyper). For the proper diagnosis of SCH, it is most important to be able to correctly evaluate the serum TSH levels, which have numerous unique characteristics. We also need to be versed in TSH harmonization, which was recently launched world-wide. In this review, we will attempt to determine the best clinical approaches to the treatment of subclinical thyroid dysfunction based on recent guidelines published from several countries and novel findings of several recent large-scale clinical studies.

Secondary Osteoporosis and Metabolic Bone Diseases

Fragility fracture is a worldwide problem and a main cause of disability and impaired quality of life. It is primarily caused by osteoporosis, characterized by impaired bone quantity and or quality. Proper diagnosis of osteoporosis is essential for prevention of fragility fractures. Osteoporosis can be primary in postmenopausal women because of estrogen deficiency. Secondary forms of osteoporosis are not uncommon in both men and women. Most systemic illnesses and organ dysfunction can lead to osteoporosis. The kidney plays a crucial role in maintaining physiological bone homeostasis by controlling minerals, electrolytes, acid-base, vitamin D and parathyroid function. Chronic kidney disease with its uremic milieu disturbs this balance, leading to renal osteodystrophy. Diabetes mellitus represents the most common secondary cause of osteoporosis. Thyroid and parathyroid disorders can dysregulate the osteoblast/osteoclast functions. Gastrointestinal disorders, malnutrition and malabsorption can result in mineral and vitamin D deficiencies and bone loss. Patients with chronic liver disease have a higher risk of fracture due to hepatic osteodystrophy. Proinflammatory cytokines in infectious, autoimmune, and hematological disorders can stimulate osteoclastogenesis, leading to osteoporosis. Moreover, drug-induced osteoporosis is not uncommon. In this review, we focus on causes, pathogenesis, and management of secondary osteoporosis.

Thyroid-stimulating hormone is associated with trabecular bone score and 5-year incident fracture risk in euthyroid postmenopausal women: the OsteoLaus cohort

Thyroid-stimulating hormone (TSH) excess or deficiency influences bone density and fracture risk. Nevertheless, does TSH in the reference range influence bone health? In euthyroid postmenopausal women, TSH levels in the reference range were positively associated with trabecular bone score and negatively with incident fractures, without affecting BMD.

PURPOSE

Subclinical hyperthyroidism is associated with low bone mineral density (BMD) and increased fracture risk. In healthy postmenopausal women, association between thyroid-stimulating hormone (TSH) in the normal range and BMD is contradictory. Trabecular bone score (TBS), an index of bone micro-architecture, is often decreased in secondary osteoporosis (OP). The aim was to determine the association between thyroid hormones (TSH, fT4) and BMD, TBS, and the incident 5-year OP fractures, in euthyroid post-menopausal women.

METHODS

We assessed 1475 women of the CoLaus/OsteoLaus cohort. We evaluated BMD at lumbar spine, femoral neck and total hip, lumbar spine TBS, and vertebral fracture with DXA. Incident major OP fractures were evaluated 5 years later by questionnaire and DXA. Women with anti-osteoporotic, antidiabetic, thyroid-modifying, hormone replacement, or systemic corticoid treatment were excluded.

RESULTS

Five hundred thirty-three women (age 68.4 ± 7.3 years, BMI 25.9 ± 4.6 kg/m2, TSH 2.03 ± 0.87 mU/l, fT4 15.51 ± 1.85 pmol/l) met the inclusion criteria. There was no significant association between TSH or fT4 and BMD measures at any site. A positive association was found between TSH and TBS (β = 0.138, p < 0.01), even after adjusting for age, BMI, and duration of menopause (β = 0.086, p < 0.05). After a 5-year follow-up, women with incident major OP fractures had lower TSH levels (1.77 ± 0.13 vs. 2.05 ± 0.04 mU/l, p < 0.05) than women without fractures, while no difference was found for fT4.

CONCLUSION

In euthyroid postmenopausal women, TSH levels were positively associated with TBS and negatively with incident fractures, without affecting BMD. Further studies are needed to evaluate the influence of thyroid hormones on TBS.

Application and prospect of trabecular bone score in differentiated thyroid cancer patients receiving thyrotropin suppression therapy

Thyroid-stimulating hormone (TSH) suppression therapy is one of the common treatments for most patients with differentiated thyroid cancer (DTC). Unfortunately, its detrimental effects on bone health are receiving increasing attention. It may increase the risk of osteoporosis and osteoporotic fractures. The trabecular bone score (TBS) is a relatively new gray-scale texture measurement parameter that reflects bone microarchitecture and bone strength and has been shown to independently predict fracture risk. We reviewed for the first time the scientific literature on the use of TBS in DTC patients on TSH suppression therapy and aim to analyze and compare the utility of TBS with bone mass strength (BMD) in the management of skeletal health and prediction of fracture risk. We screened a total of seven relevant publications, four of which were for postmenopausal female patients and three for all female patients. Overall, postmenopausal female patients with DTC had lower TBS and a significant reduction in TBS after receiving TSH suppression therapy, but their BMD did not appear to change significantly. In addition, TBS was also found to be an independent predictor of osteoporotic fracture risk in postmenopausal women with DTC receiving TSH suppression therapy. However, due to limitations in the number of studies and study populations, this evidence is not sufficient to fully demonstrate the adverse effects of TSH suppression therapy on patients' TBS or BMD and the efficacy of TBS, and subsequent larger and more case-cohort studies are needed to further investigate the relationship and application of TBS to TSH suppression therapy in terms of skeletal health impairment and fracture risk in DTC patients.

Effect of TSH Suppression Therapy on Bone Mineral Density in Differentiated Thyroid Cancer: A Systematic Review and Meta-analysis

CONTEXT

Because subclinical hyperthyroidism increases the risk of osteoporosis and fractures, concerns are growing about the long-term skeletal safety of TSH suppression therapy after total thyroidectomy in patients with differentiated thyroid cancer (DTC).

OBJECTIVE

We aimed to determine the effect of TSH suppression therapy on bone mineral density (BMD) in DTC patients.

METHODS

We searched PubMed, Embase, the Cochrane library, and other sources. Eligible observational studies included DTC patients who underwent TSH suppression therapy and BMD measurement. Two independent reviewers extracted data on the studies' characteristics and outcomes and determined their risk of bias. Data were extracted from each study for postmenopausal/premenopausal women's and men's lumbar spine (LS), femoral neck (FN), and total hip (TH) BMD and summed using a random-effects meta-analysis model. The weighted mean differences with 95% CIs are expressed for the differences in outcome measurements between groups.

RESULTS

Seventeen studies (739 patients and 1085 controls) were included for quantitative analysis. In postmenopausal women, TSH suppression therapy showed a significant decrease in LS BMD (-0.03; -0.05, -0.02), and a similar trend was seen in TH. In premenopausal women, TSH suppression therapy significantly increased LS BMD (0.04; 0.02, 0.06) and FN BMD (0.02; 0.01, 0.04). In men, there was no significant association between TSH suppression therapy and BMD at any site compared with the controls.

CONCLUSION

Evidence from observational studies suggests that postmenopausal women treated with TSH suppression therapy are at risk for lower BMD. Attention should be paid to long-term skeletal safety in DTC survivors.

Trabecular bone score in women with differentiated thyroid cancer on long-term TSH-suppressive therapy

INTRODUCTION

Thyrotropin stimulating hormone (TSH) suppression in patients with differentiated thyroid cancer (DTC) aims to decrease the growth and proliferation of thyroid cancer cells. However, the effect of TSH-suppressive therapy on bone microarchitecture remains undefined.

METHODS

Cross-sectional study including 43 women with DTC undergoing TSH-suppressive therapy (sTSH) compared to 20 women also on levothyroxine (LT4) therapy but with TSH in the low-normal range (nTSH) since the thyroid surgery. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA), and trabecular bone score (TBS) was evaluated using the TBS iNsigth software. Fracture risk assessed by FRAX, with and without TBS, was calculated. The relationship between suppressive therapy-related parameters and bone parameters was investigated.

RESULTS

The TBS mean values were not significantly different in the sTSH and nTSH groups (1.273 ± 0.12 vs 1.307 ± 0.14, p = 0.7197). In both groups, postmenopausal women had degraded microarchitecture (TBS 1.216 ± 0.11 vs 1.213 ± 0.09, p = 0.9333), while premenopausal women had normal microarchitecture (1.328 ± 0.11 vs 1.401 ± 0.12, p = 0.195). The percentage of all postmenopausal women with degraded TBS was 54.7%, while the percentage of osteoporosis diagnoses was 16.1%. The TBS-adjusted FRAX-probability of fracture was similar in sTSH and nTSH groups. Body mass index (BMI) and menopausal status were the only variables associated with TBS and BMD.

CONCLUSION

Trabecular microarchitecture assessed by TBS was similar between women on long-term suppressive therapy in DTC and those on LT4 replacement therapy aiming at a TSH level within the low-normal reference range. Low TBS values were observed in postmenopausal women of both groups, suggesting that not only suppressed TSH levels but also a low-normal TSH is associated with deteriorated bone microarchitecture in postmenopausal women following total thyroidectomy.

Biased and allosteric modulation of bone cell-expressing G protein-coupled receptors as a novel approach to osteoporosis therapy

On the cellular level, osteoporosis (OP) is a result of imbalanced bone remodeling, in which osteoclastic bone resorption outcompetes osteoblastic bone formation. Currently available OP medications include both antiresorptive and bone-forming drugs. However, their long-term use in OP patients, mainly in postmenopausal women, is accompanied by severe side effects. Notably, the fundamental coupling between bone resorption and formation processes underlies the existence of an undesirable secondary outcome that bone anabolic or anti-resorptive drugs also reduce bone formation. This drawback requires the development of anti-OP drugs capable of selectively stimulating osteoblastogenesis and concomitantly reducing osteoclastogenesis. We propose that the application of small synthetic biased and allosteric modulators of bone cell receptors, which belong to the G-protein coupled receptors (GPCR) family, could be the key to resolving the undesired anti-OP drug selectivity. This approach is based on the capacity of these GPCR modulators, unlike the natural ligands, to trigger signaling pathways that promote beneficial effects on bone remodeling while blocking potentially deleterious effects. Under the settings of OP, an optimal anti-OP drug should provide fine-tuned regulation of downstream effects, for example, intermittent cyclic AMP (cAMP) elevation, preservation of Ca²⁺ balance, stimulation of osteoprotegerin (OPG) and estrogen production, suppression of sclerostin secretion, and/or preserved/enhanced canonical β-catenin/Wnt signaling pathway. As such, selective modulation of GPCRs involved in bone remodeling presents a promising approach in OP treatment. This review focuses on the evidence for the validity of our hypothesis.

Treatment of Subclinical Hyperthyroidism in the Elderly: Comparison of Radioiodine and Long-Term Methimazole Treatment

Background: This study aimed to compare the effectiveness and safety of radioiodine (RAI) and long-term methimazole (MMI) in the treatment of subclinical hyperthyroidism (SH) in the elderly. Methods: From 306 patients, aged ≥65 years, with SH, 83 patients with thyrotropin <0.1 mU/L entered the study. In this randomized parallel-group trial, 41 and 42 patients were randomized to either RAI or long-term MMI treatment, respectively. Results: In the RAI and MMI groups, 3 and 4 patients were excluded due to side effects, choosing other modes of treatment, and not returning for follow-up; 35 and 36 patients completed 60 months of follow-up, respectively. In the RAI group, 23 (66%) became hypothyroid, and 12 (34%) remained euthyroid 60 months after a fixed dose of 15 mCi RAI. In the MMI group, the starting dose was 10 mg daily and decreased to 4.9 ± 1.0, 4.3 ± 1.0, 4.4 ± 1.4, 4.3 ± 1.8, and 3.7 ± 1.3 mg after 1, 2, 3, 4, and 5 years of continuous MMI treatment, employing titration method. By the end of study, 34 (94%) patients were euthyroid and 2 patients with diffuse goiter developed spontaneous hypothyroidism with MMI treatment. Minor adverse events occurred in both groups in the first four months of treatment. No death or serious side effects were observed during 60 months of follow-up. Conclusions: Both RAI and long-term low-dose MMI therapies are effective and safe for treatment of SH in the elderly.

Skeletal health in patients with differentiated thyroid carcinoma

Osteoporosis and fractures are important comorbidities in patients with differentiated thyroid cancer (DTC), with potential negative impact on quality of life and survival. The main determinant of skeletal fragility in DTC is the thyrotropin (TSH)-suppressive therapy, which is commonly recommended to prevent disease's recurrence, especially in patients with structural incomplete response after thyroid surgery and radio-iodine therapy. TSH-suppressive therapy can stimulate bone resorption with consequent bone loss, deterioration of bone microstructure and high risk of fragility fractures. The skeletal effects of TSH-suppressive therapy may be amplified when thyroid cancer cells localize to the skeleton inducing alterations in bone remodelling, impairment of bone structure and further increase in risk of fractures. The management of skeletal fragility in DTC may be challenging, since prediction of fractures is a matter of uncertainty and data on effectiveness and safety of bone-active agents in this clinical setting are still scanty. This review deals with pathophysiological, clinical and therapeutic aspects of skeletal fragility of patients with DTC.

Bone metabolism is a key factor for clinical outcome of tibial plateau fractures

Purpose

Given that tibial plateau fractures (TPF) are rare, they may pose a challenge to the treating surgeon due to their variety of complex fracture patterns. Numerous studies have identified potential fracture-specific, surgery-related, and patient-related risk factors for impaired patient outcomes. However, reports on the influence of bone metabolism on functional outcomes are missing.

Methods

In a retrospective multicenter cohort study, 122 TPF of 121 patients were analyzed with respect to radiological and clinical outcomes (Rasmussen) with a mean follow-up of 35.7 ± 24.9 months. The risk factor assessment included bone metabolism-affecting comorbidities and medication.

Results

The findings showed that 95.9% of the patients reported a good-to-excellent clinical outcome, and 97.4% reported a good-to-excellent radiological outcome. Logistic regression revealed that potentially impaired bone metabolism (IBM) was an independent risk factor for the clinical (p = 0.016) but not the radiological outcome (Table 4). Patients with 41-type B fractures and a potential IBM had a seven times higher risk to present a fair-to-poor clinical outcome [OR 7.45, 95 CI (4.30, 12.92)]. The most common objective impairment was a limited range of motion in 16.4% of the patients, especially in 41-type C fractures (p = 0.06). The individual failure analysis additionally identified surgery-related options for improvement.

Conclusion

This study demonstrated that potential IBM was an independent risk factor for a poor-to-fair clinical outcome.

Trabecular bone deterioration in differentiated thyroid cancer: Impact of long-term TSH suppressive therapy

Background

Conflicting results has been reported regard osteoporosis and fractures in patients with Differentiated Thyroid Cancer (DTC). Our objective was to evaluate the long‐term effects of TSH suppression therapy with Levothyroxine (LT4) on trabecular bone score (TBS) and bone mineral density (BMD) in females with DTC after thyroidectomy.

Methods

About 145 women with resected DTC and receiving long‐term TSH therapy, were stratified according to the degree of TSH suppression. Mean duration of follow‐up was 12.3 ± 6.1 years. BMD and TBS, were assessed using dual‐energy X‐ray absorptiometry (DXA) and TBS iNsight (Med‐Imaps), at baseline (1‐3 months after surgery) and at the final study visit.

Results

In patients stratified by duration of TSH suppression therapy (Group I, 5‐10 years; Group II, >10 years), slight increases from baseline TSH levels were observed. Significant decreases in LS‐BMD and FN‐BMD were seen in patients after >10 years. TBS values were lower in Groups I (1.289 ± 0.122) and II (1.259 ± 0.129) compared with baseline values (P = .0001, both groups). Regarding the degree of TSH suppression, TBS was significantly reduced in those with TSH < 0.1 µU/mL (P = .0086), and not in patients with TSH suppression of 0.1.‐0.5 or >0.5 µU/mL.

Conclusions

We found deterioration of trabecular structure in patients with DTC and TSH suppression therapy below 0.1 µU/mL and after 5‐10 years of follow‐up. Significant changes in BMD according to TSH levels were not observed. Trabecular Bone Score is a useful technique for identifying thyroid cancer patients with risk of bone deterioration.

The Influence of Thyroid Pathology on Osteoporosis and Fracture Risk: A Review

Thyroid hormones are important factors that regulate metabolism and cell differentiation throughout the human body. A complication of thyroid pathology is represented by an alteration of the bone metabolism which can lead to osteoporosis and fragility fractures, known to have a high mortality rate. Although there is a consensus on the negative impact of hyperthyroidism on bone metabolism, when referring to hypothyroidism, subclinical hypothyroidism, or subclinical hyperthyroidism, there is no general agreement. The aim of our review was to update clinicians and researchers about the current data regarding the bone health in hypothyroidism, subclinical hypothyroidism, and subclinical hyperthyroidism patients. Thyroid disorders have an important impact on bone metabolism and fracture risk, such that hyperthyroidism, hypothyroidism, and subclinical hyperthyroidism are associated with a decreased bone mineral density (BMD) and increased risk of fracture. Subclinical hypothyroidism, on the other hand, is not associated with osteoporosis or fragility fractures, and subclinical hyperthyroidism treatment with radioiodine could improve bone health.