The effects of thyrotropin-suppressive therapy on bone metabolism in patients with well-differentiated thyroid carcinoma

Association between serum TSH concentration and bone mineral density: an umbrella review

INTRODUCTION

The aim of this study was to summarize the results of previous studies, standardize the data, and present new statistical results in order to provide physicians with clinically significant outcomes regarding the association between serum TSH concentration and bone mineral density (BMD).

METHODS

To perform this umbrella review, a systematic search was conducted in which major online medical databases, such as PubMed, Web of Science, Embase, Scopus, Cochrane Library, and Google Scholar, were searched for meta-analyses and systematic reviews regarding the effect of TSH on BMD. Furthermore, all primary studies were screened for statistical analysis.

RESULTS

The statistical outcomes of the present study were based on the data of 75,898 patients. The pooled risk ratio of any kind of fracture in patients with subclinical hyperthyroidism was estimated to be 1.36 (95% CI: 1.18-1.56; p < 0.001). The SMD for BMD in the distal radius in male patients receiving L-thyroxine suppression therapy was estimated to be -0.61 (95% CI: -1.10-(-0.11); p = 0.02). Furthermore, the pooled risk ratio of any fracture in patients receiving L-thyroxine suppression therapy was estimated to be 1.98 (95% CI: 0.98 - 3.98; p = 0.06). In these patients, the BMD may significantly differ from that in non-treated patients. However, the difference depends on the type of bone.

CONCLUSIONS

Our data confirmed that subclinical hyperthyroidism has a detrimental effect on bones, causing decreased BMD. Based on the obtained results, the authors suggest that a reduced TSH serum level itself may be an individual factor associated with decreased BMD and, thus, with a greater risk of bone fracture. Nevertheless, it should be noted that the effects of TSH suppression therapy differ between areas of interest for assessing BMD. Furthermore, the results have shown that this issue may, in specific areas, concern not only postmenopausal women but also male patients. These conclusions should contribute to a careful consideration of the application of TSH suppressive therapy in all patients. Particular attention should be given to patients after DTC, while all the advantages and disadvantages of implementing L-thyroxine therapy should be individually considered.

Differentiated thyroid cancer: a focus on post-operative thyroid hormone replacement and thyrotropin suppression therapy

PURPOSE

This review focuses on post-operative thyroid hormone replacement and thyrotropin suppression therapy in patients with differentiated thyroid cancer.

METHODS

A clinical review.

RESULTS

Differentiated thyroid cancers (DTC), including papillary and follicular thyroid cancers, have an excellent prognosis and their management leverages a unique set of clinical tools arising from homology to the normal thyroid follicular cell. Surgery is the cornerstone of initial management, and post-operative care often requires thyroid hormone replacement therapy, which may be approached with the intent of physiologic normalization or used pharmacologically to suppress TSH as part of a DTC treatment.

CONCLUSION

Management of DTC and approaches to TSH suppression are tailored to an individual's risk of DTC recurrence and are adjusted to a patient's clinical status and comorbidities over time with the goal of mitigating risk and maximizing benefit.

Evaluation and Management of Bone Health in Patients with Thyroid Diseases: A Position Statement of the Korean Thyroid Association

Thyroid hormones play an important physiological role in maintaining adult bone structure and strength. Consequently, thyroid dysfunction is related to skeletal outcomes. Overt hyperthyroidism is an established cause of high bone turnover with accelerated bone loss, leading to osteoporosis and increased fracture risk. Hyperthyroidism induced by thyroid-stimulating hormone-suppressive therapy in patients with differentiated thyroid cancer is a cause of secondary osteoporosis. In contrast, there is a lack of evidence on the negative impact of hypothyroidism on bone health. Considering the clinical updates on the importance of bone health in thyroid dysfunction, the Task Force from the Clinical Practice Guidelines Development Committee of the Korean Thyroid Association recently developed a position statement on the evaluation and management of bone health of patients with thyroid diseases, particularly focused on endogenous hyperthyroidism and thyroid-stimulating hormone-suppressive therapy-associated hyperthyroidism in patients with differentiated thyroid cancer. Herein, we review the Korean Thyroid Association's position statement on the evaluation and management of bone health associated with thyroid diseases.

The risk between thyrotropin suppression and bone mineral density in differentiated thyroid cancer

BACKGROUND

The effect of thyroid stimulating endocrine (TSH) suppression medical aid on bone mineral density (BMD) of patients with differentiated thyroid carcinoma (DTC) or differentiated thyroid malignant neoplastic disease is still controversial. Our aim was to investigate the effect of TSH suppression therapy on BMD of patients with DTC.

METHODS

A total of 1651 DTC patients with TSH-suppression medical care were analyzed by RevMan 5.3 software (https://training.cochrane.org/online-learning/core-software/revman/revman-5-download) in the present study. The PubMed and Embase databases were consistently hunted for works revealed through July 29, 2022.

RESULTS

The results indicated that a significant association between femoral bone mineral density (FN-BMD) (P = .02) or lumbar spine bone mineral density (L-BMD) (P = .04) and DTC patients with TSH-suppression therapy. However, the total hip bone mineral density (TH-BMD) was not significantly related to DTC patients with TSH-suppression therapy (P = .11). For premenopausal women, it was shown that TH-BMD (P = .02) or L-BMD (P = .01) were closely related to DTC patients with TSH-suppression therapy. However, there was no relationship between FN-BMD and DTC patients with TSH-suppression therapy (P = .06). For postmenopausal women, TH-BMD was closely related to DTC patients with TSH-suppression therapy (P = .02). It was revealed that there was no significant difference between L-BMD (P = .16) or FN-BMD (P = .26) and DTC patients with TSH-suppression therapy. For men, there was no relationship between FN-BMD (P = .94) or L-BMD (P = .29) and DTC patients with TSH-suppression therapy.

CONCLUSION

Our systematic review has demonstrated that TSH inhibition treatment mainly influence the TH-BMD or L-BMD of the DTC patients who were premenopausal women; the TH-BMD of the DTC patients who were postmenopausal women. In addition, there was no influence on the FN-BMD or L-BMD of the DTC patients who were men.

Proportion of serum thyroid hormone concentrations within the reference ranges in athyreotic patients on levothyroxine monotherapy: a retrospective study

Background

In patients receiving thyroid-stimulating hormone (TSH) suppressive therapy with levothyroxine (LT₄) after total thyroidectomy for thyroid cancer, thyroid function tests should be performed to adjust the LT₄ dose. Specifically, serum TSH concentrations are commonly measured because TSH suppression is necessary according to thyroid cancer risk. The aim of the present study was to elucidate whether free thyroxine (FT₄) or free triiodothyronine (FT₃) indicates better for adjusting the dose in athyreotic patients on LT₄ monotherapy after total thyroidectomy.

Methods

We retrospectively studied the compatibility of free thyroid hormone (FT₄ and FT₃) concentrations with reference ranges in athyreotic patients on LT₄ monotherapy after total thyroidectomy.

Results

We identified 2210 consecutive patients from their medical records. Of these patients, 250 had both FT₄ and FT₃ concentrations in addition to TSH. Two hundred seven had serum TSH concentrations below the reference range (0.5–5.0 μIU/mL), while 43 had them within the reference range. In the 207 patients with TSH concentrations below the reference range, 61 patients (29.5%) had FT₄ concentrations within the reference range (0.9–1.7 ng/dL) and 146 patients (70.5%) had FT₄ concentrations above the reference range. In contrast, 10 patients (4.8%) had FT₃ concentrations below the reference range (2.3–4.0 pg/mL) and 8 (3.9%) had FT₃ concentrations above the reference range; 189 patients (91.3%) had concentrations within the reference range. Of the 43 patients with TSH concentrations within the reference range, 25 (58.1%) had FT₄ concentrations within the reference range and 18 (41.9%) had FT₄ concentrations above the reference range. While, 11 patients (25.6%) had FT₃ concentrations below the reference range and one (2.3%) had FT₃ concentrations above the reference range; hence, 31 patients (72.1%) had FT₃ concentrations within the reference range.

Conclusion

This study showed that measuring FT₃ concentrations rather than FT₄ concentrations as the subsequent parameter of thyroid function might be more useful for disease management in terms of the proportion of serum thyroid hormone concentrations within the reference ranges. Furthermore, FT₃ measurement could be useful in providing more detailed treatments, including avoiding more aggressive TSH suppressive therapy and identifying the presence of low T₃ syndrome in the background.

99Tc-Methylene Diphosphonate Treatment is Safe and Efficacious for Osteoporosis in Postmenopausal Differentiated Thyroid Cancer Patients Undergoing TSH Suppression: A Three-Center Non-Randomized Clinical Study

Objective

To investigate the effects of ⁹⁹Tc-methylene diphosphonate (⁹⁹Tc-MDP) on osteoporosis (OS) in postmenopausal patients with differentiated thyroid cancer (DTC) under thyroid stimulating hormone (TSH) suppression.

Patients and Methods

Patients (n = 142) were divided into two groups: (1) ⁹⁹Tc-MDP (n = 70) and (2) alendronate (n = 72) treatments (NCT 02304757). Bone mineral density (BMD) in the lumbar spine and hip was evaluated by DXA, along with bone turnover markers, safety, and quality of life (QOL) using SF-36 at three time points: before treatment and at 6 and/or 12 months after treatment.

Results

The percentage change of BMD in total lumbar spine or hip showed no significant difference throughout the study (P > 0.025). ⁹⁹Tc-MDP and alendronate treatment alone significantly increased BMD in the lumbar spine, but alendronate treatment also significantly increased BMD in total hip at 6 and 12 months, as compared with the baseline. There were no significant differences in the results of the SF-36 scores between the two treatment groups at any time during the whole study period. ⁹⁹Tc-MDP significantly increased bone formation markers of osteocalcin at 6 and 12 months (P all < 0.05), PINP at 12 months (P = 0.001), and bone resorption markers of β-CTX at 6 and 12 months (p < 0.05) as compared with the alendronate treated group. No adverse event was observed in the ⁹⁹Tc-MDP treatment group compared with alendronate (P = 0.014).

Conclusion

⁹⁹Tc-MDP was as efficacious as alendronate in the improvement of lumbar BMD for DTC patients with OS under TSH stimulation. ⁹⁹Tc-MDP was shown to be safe and improved patients’ QOL.

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.

Thyrotropin, Hyperthyroidism, and Bone Mass

Thyrotropin (TSH), traditionally seen as a pituitary hormone that regulates thyroid glands, has additional roles in physiology including skeletal remodeling. Population-based observations in people with euthyroidism or subclinical hyperthyroidism indicated a negative association between bone mass and low-normal TSH. The findings of correlative studies were supported by small intervention trials using recombinant human TSH (rhTSH) injection, and genetic and case-based evidence. Genetically modified mouse models, which disrupt the reciprocal relationship between TSH and thyroid hormone, have allowed us to examine an independent role of TSH. Since the first description of osteoporotic phenotype in haploinsufficient Tshr +/- mice with normal thyroid hormone levels, the antiosteoclastic effect of TSH has been documented in both in vitro and in vivo studies. Further studies showed that increased osteoclastogenesis in Tshr-deficient mice was mediated by tumor necrosis factor α. Low TSH not only increased osteoclastogenesis, but also decreased osteoblastogenesis in bone marrow-derived primary osteoblast cultures. However, later in vivo studies using small and intermittent doses of rhTSH showed a proanabolic effect, which suggests that its action might be dose and frequency dependent. TSHR was shown to interact with insulin-like growth factor 1 receptor, and vascular endothelial growth factor and Wnt pathway might play a role in TSH's effect on osteoblasts. The expression and direct skeletal effect of a biologically active splice variant of the TSHβ subunit (TSHβv) in bone marrow-derived macrophage and other immune cells suggest a local skeletal effect of TSHR. Further studies of how locally secreted TSHβv and systemic TSHβ interact in skeletal remodeling through the endocrine, immune, and skeletal systems will help us better understand the hyperthyroidism-induced bone disease.

Bone Mineral Density in Adult Survivors of Pediatric Differentiated Thyroid Carcinoma: A Longitudinal Follow-Up Study

Background: Survivors of pediatric differentiated thyroid carcinoma (DTC) receive thyrotropin-suppressive therapy to minimize disease recurrence. However, knowledge about long-term effects of subclinical hyperthyroidism on bone mineral density (BMD) in pediatric DTC survivors is scarce, as is the information regarding long-term consequences of permanent hypoparathyroidism on BMD. We evaluated BMD in pediatric DTC survivors and investigated if BMD was affected by subclinical hyperthyroidism and/or permanent hypoparathyroidism during long-term follow-up. Methods: In this nationwide longitudinal study, we determined BMD in the lumbar spine and femur by dual energy X-ray absorptiometry in 65 pediatric DTC survivors. Measurements were repeated after minimal 5 years of follow-up in 46 pediatric DTC survivors. BMD results were evaluated according to the recommendations of the International Society for Clinical Densitometry (ISCD) and WHO. At both visits, we determined biochemical parameters and markers of bone resorption (C-terminal telopeptide of type I collagen [β-CTX]) and formation (N-propeptide of type I collagen [PINP] and osteocalcin). Results: First and second BMD measurements were done after a median follow-up of 17.0 (interquartile range [IQR] 8.0-25.0) and 23.5 (IQR 14.0-30.0) years after diagnosis, respectively. Median age at diagnosis was 15 years (IQR 13.0-17.0). Twenty-nine percent of the survivors had subclinical hyperthyroidism. In most survivors, BMD T- and Z-scores were within the reference range during both BMD evaluations. However, after 23.5 years of follow-up, a low BMD was found in 13.0%. In the 13 survivors with permanent hypoparathyroidism, BMD values did not differ after 5 years of follow-up compared with baseline values or in comparison with the 33 survivors without permanent hypoparathyroidism. During follow-up, turnover markers β-CTX and PINP remained stable. Conclusions: This longitudinal study of pediatric DTC survivors demonstrated normal and stable median lumbar spine and femur BMD values after a median time of 17 and 23.5 years after diagnosis. However, compared with controls, a lower BMD was still found in 13.0% after prolonged follow-up despite intensive follow-up. Based on the studied follow-up period, these data do not provide convincing evidence in support of standard monitoring of bone mass among DTC survivors, but may be restricted to individual cases at low frequency. Trial Registration: This follow-up study was registered in The Netherlands Trial Register under no. NL3280 (www.trialregister.nl/trial/3280).

Evaluation of osseous changes in dental panoramic radiography using radiomorphometric indices in patients with hyperthyroidism

OBJECTIVE

The aim of the present study was to compare radiomorphometric measurements on panoramic images of patients with hyperthyroidism (HT) to those of a control population.

STUDY DESIGN

In this retrospective study, the mental index (MI), inferior panoramic mandibular index (PMI), antegonial index (AI), gonial index (GI), and mandibular cortical index (MCI) were evaluated on dental panoramic radiographs (DPRs) of 40 patients with HT and 40 healthy age- and sex-matched individuals and compared between the groups. Quantitative data (MI, PMI, AI, and GI) were analyzed with the Student t and Mann-Whitney U tests. Categorical data (MCI) were analyzed with the chi-square test.

RESULTS

Statistically significant differences between the patient and control groups were found for inferior PMI (P = .001) and AI (P = .017) values, with smaller mean values among the patients. However, the measurements of MI (P = .59) and GI (P = .164) and the MCI distribution (P = .13) were similar in both groups.

CONCLUSIONS

Evaluating the radiomorphometric indices of inferior PMI and AI on the DPRs of patients with HT who are at high risk of secondary osteoporosis could be helpful in the early diagnosis of osteoporotic changes and in formulating surgical treatment plans.

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.

Effects of thyroid-stimulating hormone suppression after thyroidectomy for thyroid cancer on bone mineral density in postmenopausal women: a systematic review and meta-analysis

OBJECTIVES

We assessed thyroid-stimulating hormone (TSH) suppression effects on bone mineral density (BMD) in postmenopausal women who underwent thyroidectomy.

DATA SOURCES

PubMed, EMBASE, Cochrane Library, Web of Science and SCOPUS were searched from inception to 24 February 2021.

STUDY SELECTION

Case-control studies were included.

DATA EXTRACTION AND SYNTHESIS

Two authors independently reviewed the studies, extracted the data and performed meta-analysis of eligible studies.

RESEARCH DESIGN AND METHODS

Studies evaluating BMD in postmenopausal women with thyroid cancer who had thyroidectomy and levothyroxine therapy were included. Differences in BMD were presented as standardised mean differences (SMDs). Meta-analyses were conducted using a random-effects model.

RESULTS

Analysis of 16 case-control studies (426 patients and 701 controls without thyroid cancer) showed that stringent TSH suppression (TSH <0.10 mIU/L) after thyroidectomy had deleterious effects on the BMD of the lumbar spine in postmenopausal women compared with controls (SMD -0.55; 95% CI -0.99 to -0.10; I²=75.8%). There was no significant difference in patients with moderate TSH suppression (TSH 0.10-0.49 mIU/L). TSH suppression in postmenopausal women was not significantly associated with lower femoral neck BMD. Subgroup analysis of the lumbar spine showed that the association between stringent TSH suppression and lower BMD was consistent among studies with >10 years of follow-up (SMD -0.32; 95% CI -0.50 to -0.14). Subgroup analysis of the femoral neck showed that total thyroidectomy was related to detrimental effects on the BMD of the femoral neck (SMD -0.60; 95% CI -0.89 to -0.31; I²=90.4%), but near-total thyroidectomy was not (SMD 0.00; 95% CI -0.30 to 0.30; I²=55.6%).

CONCLUSIONS

Stringent TSH suppression had deleterious effects on the BMD of the lumbar spine after thyroidectomy in postmenopausal women. Further studies are needed to determine whether stringent TSH suppression after thyroidectomy increases the fracture risk.

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.

Effect of Thyroid-Stimulating Hormone Suppression on Muscle Function After Total Thyroidectomy in Patients With Thyroid Cancer

CONTEXT

Thyroid-stimulating hormone (TSH) suppression is recommended to reduce tumor recurrence following surgery for differentiated thyroid cancer (DTC). However, prolonged subclinical hyperthyroidism caused by levothyroxine treatment has deleterious effects on various organs.

OBJECTIVE

To evaluate the relationships of TSH concentration with muscle mass, muscle strength, and physical performance related to sarcopenia in patients with DTC undergoing TSH suppression following surgery.

METHODS

We studied 134 patients of >60 years who were undergoing TSH suppression therapy following surgery for DTC. We evaluated muscle mass and muscle function-related parameters and diagnosed sarcopenia using the threshold for Asian people.

RESULTS

The participants were 68.3 ± 7.2 years old and 36/134 (26.9%) were diagnosed with sarcopenia. They were allocated to high-TSH and low-TSH groups using a threshold concentration of 0.40 μU/mL, and grip strength was significantly lower in the low-TSH group. The data were further analyzed according to age and sex, and in the low-TSH group, male participants and those of <70 years were found to have significantly lower grip strength.

CONCLUSIONS

Low-TSH concentrations is associated with low grip strength, and this is most pronounced in individuals of <70 years of age. Therefore, muscle function should be considered an adverse effect of TSH suppression in patients with DTC who undergo TSH suppression therapy, especially in men of <70 years.

TSH suppressive therapy and bone

Thyroid hormones stimulate bone turnover in adults by increasing osteoclastic bone resorption. TSH suppressive therapy is usually applied in patients with differentiated thyroid cancer (DTC) to improve the disease outcome. Over the last decades several authors have closely monitored the potential harm suffered by the skeletal system. Several studies and meta-analyses have shown that chronic TSH suppressive therapy is safe in premenopausal women and men. Conversely, in postmenopausal women TSH suppressive therapy is associated with a decrease of bone mineral density, deterioration of bone architecture (quantitative CT, QCT; trabecular bone score, TBS), and, possibly, an increased risk of fractures. The TSH receptor is expressed in bone cells and the results of experimental studies in TSH receptor knockout mice and humans on whether low TSH levels, as opposed to solely high thyroid hormone levels, might contribute to bone loss in endogenous or exogenous thyrotoxicosis remain controversial. Recent guidelines on the use of TSH suppressive therapy in patients with DTC give value not only to its benefit on the outcome of the disease, but also to the risks associated with exogenous thyrotoxicosis, namely menopause, osteopenia or osteoporosis, age >60 years, and history of atrial fibrillation. Bone health (BMD and/or preferably TBS) should be evaluated in postmenopausal women under chronic TSH suppressive therapy or in those patients planning to be treated for several years. Antiresorptive therapy could also be considered in selected cases (increased risk of fracture or significant decline of BMD/TBS during therapy) to prevent bone loss.

Drugs Causing Bone Loss

Drugs may cause bone loss by lowering sex steroid levels (e.g., aromatase inhibitors in breast cancer, GnRH agonists in prostate cancer, or depot medroxyprogestone acetate - DMPA), interfere with vitamin D levels (liver inducing anti-epileptic drugs), or directly by toxic effects on bone cells (chemotherapy, phenytoin, or thiazolidinedions, which diverts mesenchymal stem cells from forming osteoblasts to forming adipocytes). However, besides effects on the mineralized matrix, interactions with collagen and other parts of the unmineralized matrix may decrease bone biomechanical competence in a manner that may not correlate with bone mineral density (BMD) measured by dual energy absorptiometry (DXA).Some drugs and drug classes may decrease BMD like the thiazolidinediones and consequently increase fracture risk. Other drugs such as glucocorticoids may decrease BMD, and thus increase fracture risk. However, glucocorticoids may also interfere with the unmineralized matrix leading to an increase in fracture risk, not mirrored in BMD changes. Some drugs such as selective serotonin reuptake inhibitors (SSRI), paracetamol, and non-steroidal anti-inflammatory drugs (NSAIDs) may not per se be associated with bone loss, but fracture risk may be increased, possibly stemming from an increased risk of falls stemming from effects on postural balance mediated by effects on the central nervous system or cardiovascular system.This paper performs a systematic review of drugs inducing bone loss or associated with fracture risk. The chapter is organized by the Anatomical Therapeutic Chemical (ATC) classification.

Thyroid hormone therapy in differentiated thyroid cancer

Surgery-with or without postoperative radioiodine-is the standard of care for most patients with differentiated thyroid carcinoma (DTC). Thyroid hormone replacement therapy is the mainstay of long-term medical management. Patients treated with total thyroidectomy and some who undergo lobectomy alone require thyroid hormone therapy to restore euthyroidism with normal serum thyroid-stimulating hormone (TSH) levels. Because TSH acts as a growth factor for thyroid follicular cells (including those that are neoplastic), it can potentially affect the onset and/or progression of follicular-cell derived thyroid cancer. For this reason, some patients are placed on thyroid hormone therapy at doses that suppress secretion of TSH (suppression therapy). This mini-review looks at the potential benefits and risks of this practice in patients diagnosed with DTC. Aggressive TSH-suppressive therapy is of little or no benefit to the vast majority of patients with DTC. Practice guidelines, therefore, recommend a graded algorithm in which the potential benefits of suppression are weighed against the associated cardiovascular and skeletal risks. Large randomized controlled studies are needed to confirm the presumed oncological benefits of TSH-suppression and its causal role in adverse cardiac, skeletal, and quality of life effects and to assess the efficacy of TSH normalization in reversing or reducing these effects.

Thyroid Hormone Suppression Therapy

Thyroid hormone suppression therapy is designed to lower serum thyrotropin (TSH) levels using doses of thyroid hormone in excess of what would normally be required to maintain a euthyroid state. The basis of this therapy is the knowledge that TSH is a growth factor for thyroid cancer, so that lower serum TSH levels might be associated with decreased disease activity. However, clinical studies have not documented improved outcomes with TSH suppression, except in patients with the most advanced disease. Furthermore, there are a number of negative outcomes related to aggressive thyroid hormone therapy, including osteoporosis, fracture, and cardiovascular disease. Therefore, a graded approach to TSH suppression is recommended by the American Thyroid Association, based on initial risk and ongoing risk assessment.

Effects of Thyrotropin Suppression on Bone Health in Menopausal Women with Total Thyroidectomy

Background

This study examined the change in the trabecular bone score (TBS), areal bone mineral density (aBMD), and osteoporosis in postmenopausal women who underwent thyrotropin (TSH)-suppressive therapy for treating papillary thyroid cancer after a total thyroidectomy procedure.

Methods

We evaluated 36 postmenopausal women who received a total thyroidectomy for papillary thyroid cancer and were undergoing TSH suppressive therapy with levothyroxine. Postmenopausal women (n=94) matched for age and body mass index were recruited as healthy controls. The aBMD and TBS of the lumbar spine were compared between dual energy X-ray absorptiometry (DXA) at baseline and at follow-up after an average of 4.92 years.

Results

There was no significant difference in the rate of diagnoses of osteoporosis, osteopenia, or normal bone status between the 2 groups during the baseline DXA evaluation. However, the TBS was significantly lower whereas aBMD did not show significant difference at the time of baseline DXA measurement (1st DXA, 1.343±0.098 vs. 1.372±0.06317, P<0.001; 2nd DXA, 1.342±0.095 vs. 1.370±0.062, P<0.001). The TBS and aBMD did not differ significantly between the initial and follow-up DXA images in both groups of TSH suppressive patients and controls.

Conclusions

The average value of TBS and aBMD did not significantly change during the follow-up period. The TSH suppressive therapy was revealed as not a significant factor for the progressive deterioration of bone status during long term follow-up.

Risk of Osteoporotic Fractures after Thyroid-stimulating Hormone Suppression Therapy in Patients with Thyroid Cancer

Background

The effects of subclinical hyperthyroidism on fracture risk induced by thyroid-stimulating hormone (TSH) suppression therapy in patients with thyroid cancer still remains controversial. We performed a meta-analysis and systematic review to evaluate the effects of TSH suppression therapy on osteoporotic fracture in patients with thyroid cancer.

Methods

We performed a systematic search to identify studies which included osteoporotic fractures (hip fracture and vertebral fracture) in patients on TSH suppression therapy for thyroid cancer. Main outcome measures were occurrence and risk of osteoporotic fractures including hip and vertebral fractures between patients and controls.

Results

A systematic search yielded a total of 8 studies appropriate for review which included osteoporotic fracture outcome in patients on TSH suppression therapy for thyroid cancer. Studies with larger number of subjects showed the higher risk of osteoporotic fracture in group with TSH suppression therapy, although studies with smaller sample size presented a similar risk of fracture with control group.

Conclusions

Although studies were limited by small numbers, results suggested possible association between chronic TSH suppression therapy and the increased risk of osteoporotic fractures in patients with thyroid cancer.

Evaluation of Bone Mineral Density Using DXA and cQCT in Postmenopausal Patients Under Thyrotropin Suppressive Therapy

PURPOSE

This study aimed to examine the discrepancy in osteoporosis diagnoses between central quantitative computed tomography (cQCT) and dual-energy X-ray absorptiometry (DXA) and evaluated correlations among volumetric bone mineral density (vBMD), areal bone mineral density (aBMD), and trabecular bone score(TBS) in postmenopausal women who were undergoing TSH suppressive therapy.

METHODS

We enrolled a total of 81 postmenopausal patients [median age: 58 years; interquartile range (IQR): 57 to 60 years] receiving TSH suppressive therapy with levothyroxine after undergoing total thyroidectomy for papillary thyroid cancer. Patients were diagnosed by their bone mineral density (BMD) T-score and categorized according to a vBMD threshold of 120 mg/cm3 for osteopenia and a threshold of 80 mg/cm3 for osteoporosis.

RESULTS

When DXA and cQCT were compared, the BMD evaluation results differed in 76% of patients (n = 62; P < 0.001), and the detection rate of osteoporosis was 30.9% for cQCT and 21.0% for DXA. Sixty-two patients had discordant results; in 46 of these patients (74%) whose DXA T-scores were normal, the diagnosis shifted to osteopenia (n = 35) and osteoporosis (n = 11) according to the vBMD on cQCT (P < 0.001), and their vBMD values were significantly correlated with TBS (r = 0.293; P = 0.008). However, aBMD was not significantly correlated with TBS (r = 0.080; P = 0.480). TBS was significantly lower in patients with osteopenia (median: 1.35; IQR: 1.18 to 1.47) and osteoporosis (median: 1.28; IQR: 1.07 to 1.47) than in those with a normal BMD value (median: 1.37; IQR: 1.25 to 1.49; P = 0.041) on cQCT. There was no significant difference in TBS according to DXA BMD status (P = 0.200).

CONCLUSIONS

DXA and cQCT yielded inconsistent results, and detection of osteopenia and osteoporosis was higher using cQCT. TBS showed a more significant correlation with vBMD than with aBMD.

J-Shaped Association Between Postoperative Levothyroxine Dosage and Fracture Risk in Thyroid Cancer Patients: A Retrospective Cohort Study

Long-term administration of supraphysiologic dosages of levothyroxine can have detrimental effect on the bone. We aimed to investigate fracture incidence among post-thyroidectomy thyroid cancer patients compared with a matched comparison group, and explore the association between levothyroxine dosage and fracture risk. From the Korean National Health Insurance database, virtually all thyroid cancer patients who received thyroidectomy in Korea from January 1, 2004 to December 31, 2012 were included. Matched subjects were selected by 1:1 propensity score matching. Cox proportional hazards regression analysis was used to determine relative risk of osteoporotic fracture. Of 185,956 thyroid cancer patients identified, fracture events were observed in 1096 subjects (0.56%) over a mean 4.35 years of follow-up. Compared to the matched comparison group, thyroid cancer patients had no elevated risk of osteoporotic fracture (hazard ratio [HR] 1.03; 95% confidence interval [CI], 0.94 to 1.12); however, the highest dosage group (≥170 μg/day) showed significantly higher risk (HR 1.25; 95% CI, 1.07 to 1.45), while the second quartile dosage group (115-144 μg/day) showed lower risk (HR 0.71; 95% CI, 0.59 to 0.84) compared to a matched comparison group. When the second quartile dosage group was considered as reference, increased fracture risk was observed in those who took either lower (first quartile: adjusted HR 1.31; 95% CI, 1.08 to 1.59) or higher dosage of levothyroxine (third quartile: adjusted HR 1.50; 95% CI, 1.26 to 1.79; fourth quartile: adjusted HR 1.79; 95% CI, 1.51 to 2.13). Thyroid cancer patients were more likely to be treated with osteoporosis medication (HR 1.22; 95% CI, 1.18 to 1.26) than the matched comparison group. Both high and low dosage of levothyroxine treatment was associated with a higher risk for fractures in a J-shaped dose-dependent manner in post-thyroidectomy patients. Future studies are needed to determine how to optimize thyroid-stimulating hormone (TSH) suppression and how to screen and manage fracture risk. © 2018 American Society for Bone and Mineral Research.

Thyroid diseases and bone health

Thyroid hormones are essential for skeletal development and are important regulators of bone maintenance in adults. Childhood hypothyroidism causes delayed skeletal development, retarded linear growth and impaired bone mineral accrual. Epiphyseal dysgenesis is evidenced by classic features of stippled epiphyses on X-ray. In severe cases, post-natal growth arrest results in a complex skeletal dysplasia. Thyroid hormone replacement stimulates catch-up growth and bone maturation, but recovery may be incomplete dependent on the duration and severity of hypothyroidism prior to treatment. A severe phenotype characteristic of hypothyroidism occurs in children with resistance to thyroid hormone due to mutations affecting THRA encoding thyroid hormone receptor α (TRα). Discovery of this rare condition recapitulated animal studies demonstrating that TRα mediates thyroid hormone action in the skeleton. In adults, thyrotoxicosis is well known to cause severe osteoporosis and fracture, but cases are rare because of prompt diagnosis and treatment. Recent data, however, indicate that subclinical hyperthyroidism is associated with low bone mineral density (BMD) and an increased risk of fracture. Population studies have also shown that variation in thyroid status within the reference range in post-menopausal women is associated with altered BMD and fracture risk. Thus, thyroid status at the upper end of the euthyroid reference range is associated with low BMD and increased risk of osteoporotic fragility fracture. Overall, extensive data demonstrate that euthyroid status is required for normal post-natal growth and bone mineral accrual, and is fundamental for maintenance of adult bone structure and strength.

Long-term treatment-related morbidity in differentiated thyroid cancer: a systematic review of the literature

Background

Differentiated thyroid cancer (DTC) occurs in relatively young patients and is associated with a good prognosis and long survival. The management of this disease involves thyroidectomy, radioiodine therapy, and long-term thyroid-stimulating hormone suppression therapy (THST). The long-term effects of the treatment and the interaction between subclinical hyperthyroidism and long-term hypoparathyroidism are poorly understood. This review sought to examine the available evidence.

Methods

A PubMed search was carried out using the search terms “Thyroid Neoplasms” AND (“Thyroxine” OR “Hypocalcemia” OR “Thyrotropin”). Original English language articles published in the last 30 years studying the morbidity from thyroid-stimulating hormone (TSH) suppression and hypoparathyroidism following a surgery for DTC were retrieved and reviewed by 2 authors.

Results

Of the 3,000 results, 66 papers including 4,517 patients were selected for the present study. Studies reported on a range of skeletal (included in 34 studies, 1,647 patients), cardiovascular (17 studies, 957 patients), psychological (10 studies, 663 patients), and other outcomes (10 studies, 1,348 patients). Nine of 26 studies on patients who underwent THST showed a reduction in bone density, and 13 of 23 studies showed an increase in bone turnover markers. Skeletal effects were more marked in postmenopausal women. There was no evidence of increased fracture risk, and only little data were available on hypoparathyroidism. Four of five studies showed an increased left ventricular mass index on echocardiography, and one study showed a higher prevalence of atrial fibrillation (AF). There was little difference in basic physiological parameters and limited literature regarding symptoms or significant events. Six studies showed associations between long-term TSH suppression and impaired quality of life. Impaired glucose metabolism and prothrombotic states were also found in DTC patients.

Conclusion

There is limited literature regarding long-term DTC treatment-related morbidity, particularly regarding the effects of long-term hypocalcemia. Most studies have focused on surrogate markers and not on clinical outcomes. A large prospective study on defined clinical outcomes would help characterize the morbidity of treatment and stimulate research on tailoring treatment strategies.

Biochemical Markers Reflecting Thyroid Function in Athyreotic Patients on Levothyroxine Monotherapy

BACKGROUND

Some investigators reported that among athyreotic patients on levothyroxine (LT4) monotherapy following total thyroidectomy, the patients with normal serum thyrotropin (TSH) levels had mildly low serum free triiodothyronine (fT3) levels, whereas the patients with mildly suppressed serum TSH levels had normal serum fT3 levels, and the patients with strongly suppressed serum TSH had elevated serum fT3 levels. The objective of the present study was to clarify which of these three patient groups is closer to their preoperative euthyroid condition.

METHODS

A total of 133 consecutive euthyroid patients with papillary thyroid carcinoma who underwent a total thyroidectomy were prospectively studied. The patients' serum levels of lipoproteins, sex hormone-binding globulin, and bone metabolic markers measured preoperatively were compared with the levels measured at postoperative LT4 therapy 12 months after the thyroidectomy.

RESULTS

The postoperative serum sex hormone-binding globulin (p < 0.001) and bone alkaline phosphatase (p < 0.01) levels were significantly increased in the patients with strongly suppressed TSH levels (≤0.03 μIU/mL). The postoperative serum low-density lipoprotein cholesterol levels were significantly increased (p < 0.05), and the serum tartrate-resistant acid phosphatase-5b levels were significantly decreased (p < 0.05) in the patients with normal TSH (0.3 < TSH ≤5 μIU/mL). In the patients with mildly suppressed TSH (0.03 < TSH ≤0.3 μIU/mL) and fT3 levels equivalent to their preoperative levels, all metabolic markers remained equivalent to their preoperative levels.

CONCLUSIONS

The serum biochemical markers of thyroid function in patients on LT4 following total thyroidectomy suggest that the patients with mildly suppressed TSH levels were closest to euthyroid, whereas those with normal TSH levels were mildly hypothyroid and those with strongly suppressed TSH levels were mildly hyperthyroid. These data may provide novel information on the management of patients following total thyroidectomy for thyroid cancer or benign thyroid disease.

Elevated levels of circulating thyroid hormone do not cause the medical sequelae of hyperthyroidism

BACKGROUND

Clinicians have been reluctant to use high dose thyroid (HDT) to treat affective disorders because high circulating levels of thyroid hormone have traditionally been equated with hyperthyroidism, and understood as the cause of the medical sequelae of hyperthyroidism, such as osteoporosis and cardiac abnormalities. This conclusion is not supported by (HDT) research.

METHODS

A literature review of research related to the morbidity and mortality of HDT treatment was performed.

RESULTS

There exists a large body of research involving the use of HDT treatment to prevent the recurrence of differentiated thyroid cancer and to treat affective disorders. A review of this literature finds a lack of support for HDT as a cause of osteoporosis, nor is there support for an increase in morbidity or mortality associated with HDT. This finding contrasts with the well-established morbidity and mortality associated with Graves' disease, thyroiditis, and other endogenous forms of hyperthyroidism.

DISCUSSION

The lack of evidence that exogenous HDT causes osteoporosis, cardiac abnormalities or increases mortality compared with the significant morbidity and mortality of hyperthyroidism requires an alternative cause for the medical sequelae of hyperthyroidism. One possibility is an autoimmune mechanism.

CONCLUSION

High circulating levels of thyroid hormone is not the cause of the sequela of hyperthyroidism. The reluctance to using high dose thyroid is unwarranted.

A Study to Assess the Validity of Estimation of Serum Ostase Level in Hyperthyroid and Hypothyroid Cases

INTRODUCTION

One of the more specific assessments of the metabolic status of bone in normal and in disease conditions is the measurement of bone specific alkaline phosphatase or ostase. The measurement of serum ostase has several advantages over the measurements of other bone parameter. Because of its relatively long half-life, in-vivo (1 to 3days), it is relatively unaffected by diurnal variation.

AIM

To find the correlation of serum ostase level in hyper and hypothyroid cases and also to study the validity of routine estimation of serum ostase in hyper and hypothyroid cases so as to monitor the base level bone health on presentation.

MATERIALS AND METHODS

Serum ostase level was studied in 74 patients with disorder of thyroid function. Serum ostase level, Thyroid Stimulating Hormone (TSH), FT3, FT4 levels were estimated by chemiluminescent technique. The instrument used was Beckman- coulter Access 2. A total of 39 patients were hypothyroid, 31 were hyperthyroid and 4 patients had subclinical hyperthyroidism.

RESULTS

The serum ostase level was found to be elevated above 40 μg/L in 26 of the cases and above 16 μg/L but below 40μg/L in 5 cases of hyperthyroidism along with decrease in Bone Mineral Density (BMD). Serum ostase level was found to be directly proportional to the serum FT3 level (Normal range of serum ostase is 8-16 μg/L).

CONCLUSION

From this study, an inference can be drawn that a routine estimation of serum ostase level in hyperthyroid cases will help in proper monitoring of decrease bone turnover as indicated by increase serum ostase level. Besides, the estimation of serum ostase level in hyperthyroid cases it is found to be valid in this study, which can turn to be an important guiding parameter to the treating physician to formulate necessary protocols and guidelines for prophylaxis, treatment and to monitor the response to therapy in cases of reduced bone turnover related to hyperthyroid state.

Bone mineral density and bone microarchitecture after long-term suppressive levothyroxine treatment of differentiated thyroid carcinoma in young adult patients

Bone mineral density (BMD) seems not to be decreased in young patients given long-term suppressive doses of levothyroxine (LT4), but information regarding the bone microstructure in these patients is lacking. The aim of this study was to determine whether supraphysiologic doses of LT4, initiated during childhood or adolescence for treatment of differentiated thyroid carcinoma (DTC), have any detrimental effects on bone microarchitecture as evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT). Seventeen patients (27.3 ± 7.1 years old) with DTC with subclinical hyperthyroidism since adolescence and 34 healthy volunteers matched for age, sex, and body mass index were studied by dual-energy X-ray absorptiometry (DXA) to determine the areal BMD at the lumbar spine, hip, and proximal third of the radius. Volumetric BMD and structural parameters of the trabecular and cortical bone were assessed by HR-pQCT of the distal radius and distal tibia. DTC patients were given suppressive doses of LT4 starting at a mean age of 12.6 years, and the mean duration of treatment was 14.2 years. In DTC patients, clinical parameters did not correlate with DXA or HR-pQCT parameters. No differences were found between the patients and controls with respect to BMD and Z scores at any site evaluated by DXA, and no differences were found in the bone microstructure parameters evaluated by HR-pQCT. This cross-sectional study suggests that long-standing suppressive therapy with LT4 during the attainment of peak bone mass may have no significant adverse effects on bone density or microarchitecture.

Role of Thyroid Hormones in Skeletal Development and Bone Maintenance

The skeleton is an exquisitely sensitive and archetypal T3-target tissue that demonstrates the critical role for thyroid hormones during development, linear growth, and adult bone turnover and maintenance. Thyrotoxicosis is an established cause of secondary osteoporosis, and abnormal thyroid hormone signaling has recently been identified as a novel risk factor for osteoarthritis. Skeletal phenotypes in genetically modified mice have faithfully reproduced genetic disorders in humans, revealing the complex physiological relationship between centrally regulated thyroid status and the peripheral actions of thyroid hormones. Studies in mutant mice also established the paradigm that T3 exerts anabolic actions during growth and catabolic effects on adult bone. Thus, the skeleton represents an ideal physiological system in which to characterize thyroid hormone transport, metabolism, and action during development and adulthood and in response to injury. Future analysis of T3 action in individual skeletal cell lineages will provide new insights into cell-specific molecular mechanisms and may ultimately identify novel therapeutic targets for chronic degenerative diseases such as osteoporosis and osteoarthritis. This review provides a comprehensive analysis of the current state of the art.

The effect of thyroid stimulating hormone suppressive therapy on bone geometry in the hip area of patients with differentiated thyroid carcinoma

Subclinical hyperthyroidism has been reported to increase the fracture risk. However, the effect of thyroid stimulating hormone (TSH) suppressive therapy on bone geometry in the hip area of patients with differentiated thyroid carcinoma (DTC) is still unclear. The aim of this study was to investigate the effect of TSH suppression on bone geometry in the hip area of pre- and postmenopausal women with DTC. We conducted a retrospective cohort study including 99 women with DTC (25 pre- and 74 postmenopausal) who had received TSH suppressive therapy for at least 3years and 297 control subjects (75 and 222, respectively) matched for sex and age. Bone mineral density (BMD) in the spine and hip area and bone geometry at the femoral neck measured by dual energy X-ray absorptiometry (DXA) were compared between patients and controls. The association between thyroid hormone and bone parameters was investigated. All analyses of bone parameters were adjusted for age, body mass index, and serum calcium levels. In premenopausal subjects, TSH suppressive therapy was not associated with poor bone parameters. In postmenopausal subjects, patients with DTC undergoing TSH suppression showed lower cross-sectional moment of inertia (CSMI), cross-sectional area, and section modulus and thinner cortical thickness at the femoral neck than those of control subjects, whereas their femoral neck BMD was comparable with controls. Total hip BMD was lower in postmenopausal patients than in controls. CSMI and section modulus at the femoral neck were independently associated with serum free T4 levels in postmenopausal patients. The difference in femoral neck bone geometry between patients and controls was only apparent in postmenopausal DTC patients with free T4 >1.79ng/dL (23.04pmol/l), and not in those with free T4 levels ≤1.79ng/dL (23.04pmol/l). TSH suppression in postmenopausal DTC patients was associated with decreased bone strength by altering bone geometry rather than BMD in the hip area, especially the femoral neck. This alteration in bone quality was observed only in patients with free T4 levels above the upper normal limit.

Increased Risk of Atrial Fibrillation After Treatment for Differentiated Thyroid Carcinoma

BACKGROUND

Patients with differentiated thyroid carcinoma (DTC) have a favorable prognosis after treatment with thyroidectomy, radioiodine, and TSH suppression. However, treatment is associated with long-term cardiovascular toxicity. The aim of this study was to evaluate whether there is an increased risk of atrial fibrillation (AF) in DTC patients and whether AF occurrence is related to DTC treatment.

PATIENTS AND METHODS

Incident AF was compared between 518 DTC patients and 1563 matched controls. A cumulative incidence curve was plotted, and competing risk regression analyses with adjustment for all-cause mortality were performed. Within the DTC cohort, associations between time-varying DTC treatment variables and incident AF were analyzed.

RESULTS

For both cohorts, the mean age was 48.6 years (75% of subjects were women). The AF incidence rate was 6.2/1000 person-years for DTC patients and 2.7/1000 person-years for controls. DTC patients had a 2.25-fold (95% confidence interval [CI], 1.40-3.63) and 2.47-fold (95% CI, 1.55-3.95) increased AF risk in crude and fully adjusted analyses, respectively. Within the DTC cohort, the TSH level (which was suppressed in 85.7% of patients) was not associated with AF, whereas a higher cumulative radioiodine dose slightly increased AF risk: subdistribution hazard ratio, 1.04 (95% CI, 1.01-1.08) per 50 mCi (1.85 GBq) increase, after adjustment.

CONCLUSION

Patients with DTC have an increased AF risk, independent from established AF risk factors. We could not demonstrate a relation between TSH and AF, whereas a higher cumulative radioiodine dose was associated with a slightly increased AF risk. Electrocardiogram screening for AF may be warranted during follow-up of DTC patients to allow early diagnosis and treatment of AF and to prevent its complications.

[What's new in follicular thyroid cancer management in 2014?]

The American Thyroid Association has presented new guidelines for the management of thyroid cancer. These guidelines tend to appreciate more accurately the individual risk of patients, to adapt accordingly the treatment and the follow up. The initial risk stratification has been completed, especially precising the risk of N1 patients, follicular thyroid cancers, and the prognostic impact of molecular markers. Indications, doses and modalities of radioiodine (RAI) have been reevaluated, restricting its utilization in order to avoid overtreatment of low risk patients. Moreover the response to initial treatment allows to restratify the risk of the patients, and to adapt the monitoring and the thyroid hormone therapy management. The risk of suppressive thyroid hormone therapy has also to be considered. Concerning advanced thyroid cancer, prognosis is mainly depending on its RAI sensitivity. The systemic treatment of progressive, threatening refractory cancers is nowadays based on targeted therapy. However none of these treatments has demonstrated an improvement in overall survival, and side effects are frequent. Fagin et al presented promising results concerning short term treatment with selective inhibitors of the MAPK pathway, able to partially restore RAI sensitivity of refractory lesions in murine models, and recently in human patients.

Management of endocrine disease: Secondary osteoporosis: pathophysiology and management

Osteoporosis is a skeletal disorder characterized by decreased mass and compromised bone strength predisposing to an increased risk of fractures. Although idiopathic osteoporosis is the most common form of osteoporosis, secondary factors may contribute to the bone loss and increased fracture risk in patients presenting with fragility fractures or osteoporosis. Several medical conditions and medications significantly increase the risk for bone loss and skeletal fragility. This review focuses on some of the common causes of osteoporosis, addressing the underlying mechanisms, diagnostic approach and treatment of low bone mass in the presence of these conditions.

Low BMI and low TSH value as risk factors related to lower bone mineral density in postmenospausal women under levothyroxine therapy for differentiated thyroid carcinoma

Objective

Treatment of differentiated thyroid carcinoma (DTC) includes suppression of TSH with levothyroxine therapy, which may negatively influence bone mineral density (BMD), but the effects are controversial. We aimed to evaluate the relationship between TSH-suppressive therapy and BMD in postmenopausal women with DTC.

Methodology

Cross-sectional study that assessed BMD by densitometry and risk factors for decreased BMD in 109 postmenopausal women under TSH-suppressive therapy for DTC, compared to an age-matched euthyroid women control group. Conditions that might have affected BMD were exclusion criteria.

Results

Patients were 58.4 ± 8.3 years-old, mean serum TSH was 0.21 ± 0.28μIU/ml. In BMD evaluation, T-scores were −1.09 ± 1.43 SD (lumbar spine) and −0.12 ± 1.18 SD (total femur). No significant differences were found between lumbar or femoral T-scores of patients and control group. Multivariate logistic regression analysis evidenced that low BMI and low mean TSH levels (assessed in the year of BMD measurement) were factors significantly related to lower lumbar and spinal BMD.

Conclusion

Although low TSH levels and low BMI were correlated with lower BMD, it was not observed an increased prevalence of osteopenia or osteoporosis in this cohort of post-menopausal women under levothyroxine treatment for DTC, when compared to age-matched control women. Nevertheless, such risk factors should be carefully observed in individual patients at high risk of decrease in BMD.

An examination of myth: a favorable cardiovascular risk-benefit analysis of high-dose thyroid for affective disorders

INTRODUCTION

High dose thyroid (HDT) is included in major treatment guidelines for the treatment of bipolar disorders. Yet it is seldom used partly based on perceived cardiovascular risks. The cardiovascular risks of HDT are examined.

METHODS

A literature search was conducted for the cardiovascular risks of HDT and for comparisons sake psychiatric medications. Case reports of atrial fibrillation (afib) associated with HDT are reported.

RESULTS

While hyperthyroidism is a significant cardiovascular risk factor causing a 20% premature death rate, HDT treatment does not appear to be of significant cardiovascular risk. HDT differs from hyperthyroidism in significant ways. The sequela of hyperthyroidism are increasingly tied to autoimmune complications which are absent with HDT. Equating hyperthyroidism with HDT is incorrect. The five case reports of HDT treatment associated with afib were potentially caused by other factors. If HDT increases the risks of afib, monitoring for afib would minimizes the risk. Even in overt hyperthyroidism the risk of other arrhythmias are minimal. When compared to many psychiatric medications HDT is as safe or safer.

LIMITATIONS

There are no direct studies of cardiovascular risks of HDT for affective patients. High tolerance of a medication does not necessarily imply lack of risk. The five case reports were spontaneous, other cases may not have been reported.

CONCLUSION

The cardiovascular risks of HDT appear to be low. HDT is at least as safe as or safer than many psychiatric medications. It is effective and well tolerated.

Thyrotropin suppression increases the risk of osteoporosis without decreasing recurrence in ATA low- and intermediate-risk patients with differentiated thyroid carcinoma

BACKGROUND

Levothyroxine suppression of thyrotropin (TSH) is broadly applied to patients with thyroid cancer despite lack of consensus on the optimal TSH concentration necessary to reduce cancer recurrence while minimizing toxicity from subclinical hyperthyroidism. The objectives of this study were to examine the beneficial effects and the cardiac and skeletal toxicity of TSH suppression in well-differentiated thyroid carcinoma (DTC).

METHODS

A total of 771 patients (569 women) at ATA low or intermediate risk of recurrence, with a mean age of 48±14 years, and undergoing total thyroidectomy at a tertiary care center between 2000 and 2006 were followed for a median of six and a half years. They were divided into a suppressed TSH group (median TSH ≤0.4 mIU/L) and a nonsuppressed group (median TSH >0.4 mIU/L). Structural recurrence of thyroid cancer, postoperative atrial fibrillation (AF), and osteoporosis were examined in the two groups. Osteoporosis was only examined in women.

RESULTS

A total of 43/771 (5.6%) patients recurred, 29/739 (3.9%) patients were diagnosed with postoperative osteoporosis, and 17/756 (2.3 %) were diagnosed with postoperative AF. Despite similar rates of recurrence (HR 1.02, p=0.956 [CI 0.54-1.91]), patients treated to a median TSH ≤0.4 mIU/L were at increased postoperative risk of a composite outcome of AF and osteoporosis (HR 2.1, p=0.05 [CI 1.001-4.3]) compared to those not suppressed. A differential risk of AF alone (HR 0.78, p=0.63 [CI 0.3-2.1]) was not detected, but postoperative osteoporosis was increased among women with a suppressed TSH compared to those not suppressed (HR 3.5, p=0.023 [CI 1.2-10.2]). The increased risk of postoperative osteoporosis disappeared when the patient's median TSH was maintained around 1 mIU/L.

CONCLUSION

TSH suppression significantly increases the risk of postoperative osteoporosis without changing tumor recurrence in ATA low- and intermediate-risk patients with DTC. Future interventions should focus on avoiding harm in indolent disease.

The effects of thyrotropin-suppressing therapy on bone metabolism in patients with well-differentiated thyroid carcinoma

Studies on the effects of levothyroxine (LT4) therapy on bone and bone metabolism have yielded conflicting results. This 1-year prospective study examined whether LT4 in patients with well-differentiated thyroid carcinoma (DTC) is a risk factor for bone mass loss and the subsequent development of osteoporosis. We examined 93 patients with DTC over 12months after initiating LT4 therapy (early postoperative period). We examined another 33 patients on long-term LT4 therapy for DTC (late postoperative period). Dual energy X-ray absorptiometry was performed at baseline and after 1year. The mean bone losses during the early postoperative period in the lumbar spine, femoral neck, and total hip, calculated as the percentage change between levels at baseline and 12months, were -0.88, -1.3 and -0.81%, respectively. Bone loss was more evident in postmenopausal women (lumbar spine -2.1%, femoral neck -2.2%, and hip -2.1%; all P<0.05). We compared the changes in annual bone mineral density (BMD) in postmenopausal women according to calcium/vitamin D supplementation. Bone loss tended to be higher in the postmenopausal women receiving no supplementation. There was no decrease in BMD among patients during the late postoperative period. The mean bone loss was generally greater in the early than in the late postoperative group, and this was significant at the lumbar spine (P=0.041) and femoral neck (P=0.010). TSH-suppressive levothyroxine therapy accelerates bone loss, predominantly in postmenopausal women and exclusively during the early post-thyroidectomy period.

Prevalence of silent vertebral fractures detected by vertebral fracture assessment in young Portuguese men with hyperthyroidism

BACKGROUND

Hyperthyroidism is a risk factor for reduced bone mineral density (BMD) and osteoporotic fractures. Vertebral fracture assessment (VFA) by dual-energy X-ray absorptiometry (DXA) is a radiological method of visualization of the spine, which enables patient comfort and reduced radiation exposure.

OBJECTIVES

This study was carried out to evaluate BMD and the prevalence of silent vertebral fractures in young men with hyperthyroidism.

DESIGN

We conducted a cross-sectional study in a group of Portuguese men aged up to 50 years and matched in hyperthyroidism (n=24) and control (n=24) groups.

MATERIALS AND METHODS

A group of 48 Portuguese men aged up to 50 years was divided and matched in hyperthyroidism (n=24) and control (n=24) groups. BMD (g/cm(2)) at L1-L4, hip, radius 33%, and whole body as well as the total body masses (kg) were studied by DXA. VFA was used to detect fractures and those were classified by Genant's semiquantitative method. No patient had previously been treated for hyperthyroidism, osteoporosis, or low bone mass. Adequate statistical tests were used.

RESULTS

The mean age, height, and total fat mass were similar in both groups (P≥0.05). The total lean body mass and the mean BMD at lumbar spine, hip, and whole body were significantly decreased in the hyperthyroidism group. In this group, there was also a trend for an increased prevalence of reduced BMD/osteoporosis and osteoporotic vertebral fractures.

CONCLUSIONS

The results obtained using VFA technology (confirmed by X-ray) suggest that the BMD changes in young men with nontreated hyperthyroidism may lead to the development of osteoporosis and vertebral fractures. This supports the pertinence of using VFA in the routine of osteoporosis assessment to detect silent fractures precociously and consider early treatment.

Volumetric bone mineral density and bone geometry assessed by peripheral quantitative computed tomography in women with differentiated thyroid cancer under TSH suppression

OBJECTIVE

TSH suppression therapy in patients with differentiated thyroid cancer (DTC) has been associated with adverse effects on areal bone mineral density (aBMD) only in postmenopausal women. The purpose of study was to examine the effect of TSH suppression therapy on skeletal integrity using peripheral quantitative computed tomography (pQCT) at the radius and tibia in pre- and postmenopausal women with DTC and controls.

STUDY DESIGN AND PATIENTS

Subjects included 80 women with DTC (40 pre- and 40 postmenopausal) and 89 (29 and 60, respectively) controls. pQCT was performed at the radius and tibia, Dual-energy X-ray absorptiometry (DXA) at the hip and lumbar spine, while samples were taken for calciotropic hormones and bone markers.

RESULTS

No differences were observed concerning aBMD by DXA. In premenopausal women, there were no significant differences concerning vBMD, while cortical thickness was higher at the radius in patients with DTC (P < 0·01) compared with controls. In postmenopausal women with DTC trabecular bone mineral content (BMC), area and vBMD were lower at the radius (all P < 0·05), while at the tibia trabecular BMC and vBMD were lower at the mixed transition zone (14% from the distal end, P < 0·05) compared with controls. Cortical thickness was lower at the radius (P < 0·01) in postmenopausal patients compared with controls. Serum CTX was higher in postmenopausal women with DCT (P < 0·01), while in premenopausal patients, parathyroid hormone (PTH) was lower (P = 0·01) compared with controls.

CONCLUSIONS

TSH suppression therapy is associated with higher bone resorption only in postmenopausal women; this adversely affects trabecular and cortical bone properties especially at nonweight-bearing sites such as the radius.

Bone mineral density in treated at a young age for differentiated thyroid cancer after Chernobyl female patients on TSH-suppressive therapy receiving or not Calcium-D3 supplementation

Long-term management of patients with differentiated thyroid cancer (DTC) commonly includes TSH-suppressive therapy with L-T4 and, in case of postsurgical hypoparathyroidism, Calcium-D3 supplementation, both of which may affect skeletal health. Experience with female patients treated for DTC at a young age and who were then receiving long-term therapy with L-T4 and Calcium-D3 medication is very limited to date. This cross-sectional study set out to investigate effects of Calcium-D3 supplementation and TSH-suppressive therapy on bone mineral density (BMD) in 124 young female patients treated for DTC at a mean age of 14 years and followed-up for an average of 10 years. BMD was found to be significantly higher in patients receiving Calcium-D3 medication than in patients not taking supplements. The level of ionized calcium was the strongest factor determining lumbar spine BMD in patients not receiving Calcium-D3 supplementation. Pregnancy ending in childbirth and HDL-cholesterol were associated with a weak adverse effect on spine and femoral BMD. No evidence of adverse effects of L-T4 and of radioiodine therapies on BMD was found. We conclude that Calcium-D3 medication has a beneficial effect on BMD, and that TSH-suppressive therapy does not affect BMD in women treated for DTC at young age, at least after 10 years of follow-up.

The influence of thyroid dysfunction on bone metabolism

Loss of bone mineral density due to osteoporosis is the main cause of fragility fractures and leads to dropped quality of life and increased mortality. Disturbance of balance between bone formation and bone resorption is dangerous, can cause loss of bone mass and disruption of it's architecture. Correct development, achievement of peak bone mass and normal functioning of human skeleton depend on different factors. The pivotal role in bone metabolism play thyroid hormones. Both excess as well as deficiency of fT4 and fT3 can be potentially deleterious for bone tissue. The aim of this study is to review the current literature concerning the role of thyroid hormones on bone metabolism.

Hypothalamic control of bone metabolism

Bones are structures in vertebrates that provide support to organs, protect soft organs, and give them shape and defined features, functions that are essential for their survival. To perform these functions, bones are constantly renewed throughout life. The process through which bones are renewed is known as bone remodeling, an energy demanding process sensitive to changes in energy homeostasis of the organism. A close interplay takes place between the diversity of nutritional cues and metabolic signals with different elements of the hypothalamic circuits to co-ordinate energy metabolism with the regulation of bone mass. In this review, we focus on how mouse and human genetics have elucidated the roles of hormonal signals and neural circuits that originate in, or impinge on, the hypothalamus in the regulation of bone mass. This will help to understand the mechanisms whereby regulation of bone is gated and dynamically regulated by the hypothalamus.

A favorable risk-benefit analysis of high dose thyroid for treatment of bipolar disorders with regard to osteoporosis

High dose thyroid hormone has been in use since the 1930s for the treatment of affective disorders. Despite numerous papers showing benefit, the lack of negative trials and its inclusion in multiple treatment guidelines, high dose thyroid has yet to find wide spread use. The major objection to the use of high dose thyroid is the myth that it causes osteoporosis. This paper reviews the literature surrounding the use of high dose thyroid, both in endocrinology and in psychiatry. High dose thyroid does not appear to be a significant risk factor for osteoporosis while other widely employed psychiatric medications do pose a risk. Psychiatrists are uniquely qualified to do the risk-benefit analyses of high dose thyroid for the treatment of the bipolar I, bipolar II and bipolar NOS. Other specialties do not have the requisite knowledge of the risks of alterative medications or of the mortality and morbidity of the bipolar disorders to do a full risk benefit analysis.

Treatment with thyroid hormone

Thyroid hormone deficiency can have important repercussions. Treatment with thyroid hormone in replacement doses is essential in patients with hypothyroidism. In this review, we critically discuss the thyroid hormone formulations that are available and approaches to correct replacement therapy with thyroid hormone in primary and central hypothyroidism in different periods of life such as pregnancy, birth, infancy, childhood, and adolescence as well as in adult patients, the elderly, and in patients with comorbidities. Despite the frequent and long term use of l-T4, several studies have documented frequent under- and overtreatment during replacement therapy in hypothyroid patients. We assess the factors determining l-T4 requirements (sex, age, gender, menstrual status, body weight, and lean body mass), the major causes of failure to achieve optimal serum TSH levels in undertreated patients (poor patient compliance, timing of l-T4 administration, interferences with absorption, gastrointestinal diseases, and drugs), and the adverse consequences of unintentional TSH suppression in overtreated patients. Opinions differ regarding the treatment of mild thyroid hormone deficiency, and we examine the recent evidence favoring treatment of this condition. New data suggesting that combined therapy with T3 and T4 could be indicated in some patients with hypothyroidism are assessed, and the indications for TSH suppression with l-T4 in patients with euthyroid multinodular goiter and in those with differentiated thyroid cancer are reviewed. Lastly, we address the potential use of thyroid hormones or their analogs in obese patients and in severe cardiac diseases, dyslipidemia, and nonthyroidal illnesses.

The prevalence and prognostic effects of subclinical thyroid dysfunction in dilated cardiomyopathy patients: a single-center cohort study

BACKGROUND

Subclinical thyroid dysfunction may be a risk factor for mortality in patients with heart failure and may be associated with dilated cardiomyopathy (DCM). This was a cohort study to examine the possible association between subclinical thyroid dysfunction and all-cause mortality in DCM patients, because the current evidence on this association remains elusive.

METHODS AND RESULTS

A total of 963 DCM patients were evaluated for thyroid function. Of these patients, 7.1% (n = 68) had subclinical hyperthyroidism (defined as serum thyroid-stimulating hormone [TSH] <0.35 μIU/mL), 84.7% (n = 816) had euthyroidism (TSH 0.35-5.5 μIU/mL), and 8.2% (n = 79) had subclinical hypothyroidism (TSH >5.5 μIU/mL). There was a significant difference in all-cause mortality rates between patients with euthyroidism and patients with subclinical hyper- and hypothyroidism (21%, 38.2%, and 26.6%, respectively; log-rank χ(2) = 13.104; P = .001) with mean follow-up of 3.5 years. After adjustment for other confounding factors at baseline, QRS duration, N-terminal pro-B-type natriuretic peptide, New York Heart Association functional class, left atrial diameter, and subclinical hyperthyroidism (hazard ratio 1.793, 95% CI 1.010-3.183; P = .046) emerged as significant predictors of all-cause mortality.

CONCLUSION

DCM patients with subclinical hyper- and hypothyroidism had higher all-cause mortality rates. However, only subclinical hyperthyroidism, not subclinical hypothyroidism, was an independent predictor for increased risk of all-cause mortality.

Treatment related morbidity in differentiated thyroid cancer-a survey of clinicians

Abstracts

Pharmacophysiology of bone and spinal fusion

BACKGROUND CONTEXT

In recent years, the number of complex spinal surgeries has increased significantly in the elderly population, where the prevalence of low bone density is highest. Consequently, spine surgeons often treat osteoporotic patients who are associated with higher rates of instrumentation failure. Therefore, establishing a successful fusion requires an appropriate substrate for bone formation and local bone remodeling. The fusion process can be supported by therapies that seek to shift the balance of bone homeostasis to increased formation and reduced resorption.

PURPOSE

Thorough understanding of the physiology of bone formation and adjunctive therapies can help improve fusion rates. Therefore, we present a thorough review of the latest pharmacologic agents used to enhance bone strength and surgical spinal fusion.

METHODS

Systematic review of literature.

RESULTS

Current knowledge on bone physiology has led to the development of several pharmacologic agents that enhance bone formation and strengthen the human skeleton. At present, natural supplements of vitamin D and calcium or synthetic medications like bisphosphonates are widely used before and after spine surgeries to enhance bone fusion. Additional physiologic agents, including testosterone, parathyroid hormone, calcitonin, and growth hormone, have been shown to improve bone mass density or spinal fusion in both animal and human studies. As in other medical fields, gene therapy has shown viability and promise with the use of both viral and nonviral vectors.

CONCLUSIONS

Through the understanding of bone physiology, numerous natural and synthetic pharmacologic agents have been developed to enhance the body's skeleton and to improve outcomes of spinal fusion surgery.