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

Association Between Papillary Thyroid Carcinoma and Vertebral Fracture

Suppression of TSH levels associated with levothyroxine treatment is a known risk factor for fracture. However, it is unclear whether patients with papillary thyroid carcinoma (PTC) have a higher risk of vertebral fracture (VF) before TSH suppression. The aim of the study was to examine whether the risk of VF is higher in PTC than in healthy subjects. A hospital-based, matched case-control study was conducted comparing PTC and healthy individuals. We enrolled 43 postoperative patients with PTC scheduled for radioiodine therapy and 43 age- and sex-matched healthy controls. Serum and urinary biological parameters, bone mineral density (BMD), and presence of VFs were evaluated in both groups. We compared these indices using χ2 and Mann-Whitney U-test and analyzed the association between PTC and VF by logistic regression analysis. The PTC group had higher BMI, HbA1c and phosphorus, and lower intact PTH than the control group. Lumbar and femoral neck BMD did not differ between the two groups. Prevalence of VFs was significantly higher in the PTC group (44.1%) than in the control group (16.3%). Multivariate logistic regression analyses adjusted for age, sex, and BMI identified PTC as being associated with the presence of VFs (odds ratio, 5.63; 95% confidence interval: 1.82 to 17.5). This relationship remained significant after additional adjustment for HbA1c and BMD. There is an association between PTC and a risk of VF independent of sex, BMI, glucose metabolism, and BMD, suggesting the importance of fracture risk assessment before TSH suppression.

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.

Bone quality in endocrine diseases: determinants and clinical relevance

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Is dual-energy absorptiometry accurate in the assessment of bone status of patients with chronic kidney disease?

Several patients with chronic kidney disease (CKD) have deteriorated bone status. Estimation of bone status using DXA has limitations especially in patients with CKD accompanying aortic calcifications. Quantitative CT and the trabecular bone score could be more accurate methods to estimate bone status for patients with CKD and vascular calcifications.

INTRODUCTION

It remains unclear whether dual-energy absorptiometry (DXA) is appropriate for the assessment of bone status in patients with chronic kidney disease (CKD), a disease that impacts bone health. The aims of this study were to compare DXA and central quantitative computed tomography (cQCT) and to evaluate bone status in patients with pre-dialysis CKD.

METHODS

This retrospective study included 363 healthy control subjects whose bone mineral density (BMD) was evaluated with DXA and 117 CKD patients whose BMD was evaluated using both cQCT and DXA. Diagnostic discordance was assessed between the lumbar spine (LS) and femur neck (FN) from DXA or between two modalities. The trabecular bone score (TBS) was extracted from DXA images. The volume of abdominal aortic calcification (AAC) was calculated using CT images from cQCT.

RESULTS

Using LS DXA T-score, osteoporosis was less common in the CKD group than in controls. Patients with normal LS BMD using DXA were reclassified into osteopenia or osteoporosis using cQCT in CKD patients. Among discordant subjects between FN and LS in DXA, a higher BMD of LS was more common in CKD patients than in controls. CKD patients had lower TBS than controls despite having the same diagnosis using DXA. AAC volume negatively correlated with BMD from cQCT and with TBS but not with BMD from DXA.

CONCLUSIONS

TBS and cQCT could accurately assess bone status in CKD patients since DXA may overestimate LS BMD, likely due to an increased AAC volume.

Consequences of Hyperthyroidism and Its Treatment for Bone Microarchitecture Assessed by High-Resolution Peripheral Quantitative Computed Tomography

Background: Hyperthyroidism is associated with bone mass reduction and increased fracture risk, but the effects on other important bone parameters have been sparsely examined. Therefore, we investigated bone microarchitecture and estimated bone strength by high-resolution peripheral quantitative computed tomography (HR-pQCT) in hyperthyroid patients at diagnosis and after being euthyroid for at least one year. Methods: Two approaches were used: (A) a case-control study comparing 61 hyperthyroid women with 61 euthyroid women matched for age and menopause status; (B) a follow-up study, in which 46 of the 61 women were re-examined after having been euthyroid for one year. HR-pQCT of the distal radius and tibia, and dual-energy X-ray absorptiometry (DXA) of the lumbar spine and the hip were performed. Results: In analysis A: In the radius, compared with the healthy controls, hyperthyroid patients had higher total area (16.9% ± 29.5%; p < 0.001), trabecular area (28.6% ± 45.7%; p < 0.001), and lower cortical area (-11.7% ± 23.2%; p < 0.001). Total volumetric bone mineral density (vBMD) (-13.9% ± 26.5%; p < 0.001), cortical vBMD (-5.8% ± 7.9%; p < 0.001), cortical thickness (-16.7% ± 26.0%; p < 0.001), and estimated bone strength (-6.6% ± 19.5%; p < 0.01) were lower. No significant differences were found in the tibia or in the DXA parameters. In analysis B: In the radius, significant improvements were observed in the cortical area (2.1% ± 4.6%; p < 0.01), cortical thickness (2.5% ± 5.1%; p < 0.001), and total vBMD (0.8% ± 3.0%; p < 0.05). Trabecular area decreased (-0.5% ± 1.0%; p < 0.01) and trabecular separation increased (2.0% ± 8.3%; p < 0.05). In the tibia, cortical area (3.6% ± 7.3%; p < 0.01) and cortical thickness (3.8% ± 7.6%; p < 0.01) increased, and trabecular area decreased (-0.5% ± 1.1%; p < 0.01). Areal BMD, measured by DXA, increased in the spine (1.1% ± 3.4%; p < 0.05) and in the hip (2.0% ± 3.8%; p < 0.01). Conclusions: Compared with the healthy control group, hyperthyroid women had lower vBMD, lower estimated bone strength, and compromised cortical microarchitecture in the radius. After restoration of euthyroidism, significant improvements in vBMD and cortical microarchitecture were observed, highlighting the importance of achieving and maintaining euthyroidism.

Personalized treatment for differentiated thyroid cancer: current data and new perspectives

More conservative and personalized treatment options have been developed in recent years to face the rising diagnosis of low-risk differentiated thyroid carcinoma (DTC). The present review describes the change towards a more risk-adapted management either in the treatment or in the follow-up of DTC. Particular attention is given to the innovations introduced by the latest guidelines for low-risk tumors, starting from the most appropriate extension of surgery up to the postoperative management. The emerging role of active surveillance for low-risk microcarcinoma is discussed, as well as the development of percutaneous strategies in the setting of malignant thyroid disease. The recent use of approved new systemic target therapies for advanced radioiodine refractory thyroid cancer is reported, together with the description of new compounds in trial. Finally, we provide some considerations to improve the risk evaluation in a presurgical setting, especially related to the rising role of genetics, to enable better risk-based cancer management and personalized treatment choices.

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.

DIAGNOSIS OF ENDOCRINE DISEASE: Evaluation of bone fragility in endocrine disorders

An underlying disease affecting bone health is present in up to 40% and 60% of osteoporotic post-menopausal women and men respectively. Among the disorders leading to a secondary form of osteoporosis, the endocrine diseases are highly represented. A frequent finding in patients affected with an endocrine-related forms of bone disease is that the skeletal fragility is partially independent of the bone density, since the fracture risk in these patients is related more to a reduction of bone quality than to a decrease of bone mass. As a consequence, bone mineral density evaluation by dual-X-ray Absorptiometry may be inadequate for establishing the risk of fracture in the setting of the endocrine-related forms of osteoporosis. In the recent years several attempts to non-invasively estimating bone quality have been done. Nowadys, some new tools are available in the clinical practice for optimizing the fracture risk estimation in patients with endocrine disorders. The aim of this review is to summarise the evidences regarding the role of the different imaging tools for evaluating bone density and bone quality in the most frequent forms of endocrine-related osteoporosis, such as obesity, diabetes, acromegaly, thyrotoxicosis, primary hyperparathyroidism, hypercortisolism and hypogonadism. For each of these disorders, data regarding both the current available tools and the future possible new techniques for assessing bone fragility in patients with endocrine diseases are reported.

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.