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

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.

Site specific differences in vBMD and geometry in postmenopausal women with primary hyperparathyroidism

PURPOSE

Primary Hyperparathyroidism (PHPT) is associated with catabolic effects at both trabecular and cortical bone. Mechanical loading is one of the most important natural anabolic stimuli for bone at all ages. The present study was designed to assess the impact of PHPT on vBMD and bone geometry using peripheral quantitative computed tomography (pQCT) at the radius and tibia, sites with similar structural characteristics, but subject to different loading conditions.

METHODS

We evaluated the impact of PHPT on bone, by comparing the z-scores of volumetric Bone Mineral Density (vBMD) and indices of bone geometry simultaneously at the tibia and the radius by pQCT, skeletal sites with similar structure, but subject to different loading conditions. Forty-one postmenopausal women with PHPT and 79 controls, comprised the study group.

RESULTS

At both trabecular and cortical sites, vBMD and bone geometry indices were significantly lower in patients compared with controls. In patients with PHPT, apart from a lower z-score for total vBMD (p = 0.01) at the radius, there was no other difference between the radius and the tibia at the trabecular sites. On the contrary, at cortical sites, the z-scores of cortical bone mineral content (p = 0.02), cortical vBMD (p = 0.01) and cortical cross-sectional area (p = 0.05) were significantly lower at the radius compared with the tibia, indicating that cortical bone at the weight bearing tibia might be less affected by the catabolic actions of continuous parathyroid hormone (PTH) exposure. PTH levels were positively associated with the difference in z-scores of cort BMD (r = 0.439, p < 0.01) indicating that in more severe cases, as expressed by higher PTH levels, the deleterious effects at the non-weight bearing radius might be accentuated.

CONCLUSION

We found that in postmenopausal women with PHPT, both trabecular and cortical bone are adversely affected. However, at the weight bearing tibia as compared with the radius, the deleterious effects, especially on cortical bone, seem to be attenuated.

TRIAL REGISTRATION NUMBER

NCT05426512, 21/06/2022, "retrospectively registered".

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.

Effects of TSH suppressive therapy on bone mineral density (BMD) and bone turnover markers (BTMs) in patients with differentiated thyroid cancer in Northeast China: a prospective controlled cohort study

PURPOSE

This study aimed to evaluate the effects of thyroid-stimulating hormone (TSH) suppressive therapy on bone mineral density (BMD) and bone turnover markers (BTMs) in differentiated thyroid cancer (DTC) patients after postoperative 1-2 years in Northeast China.

METHODS

Five male, sixteen premenopausal, and eight postmenopausal female DTC patients receiving TSH suppressive therapy after thyroidectomy were enrolled. Patients were matched with healthy controls in a ratio of 1:2. All participants completed postoperative 1-year follow-up, and postmenopausal women completed 2-year follow-up. We measured BMD of the lumbar spine (LS), femoral neck (FN), and total hip (TH) using dual-energy X-ray absorptiometry (DXA). Bone formation marker P1NP and bone resorption marker β-CTX were also evaluated. Fracture risks were assessed by FRAX.

RESULTS

There was no difference in BMD and BTMs between DTC patients and controls in the male group at 1-year follow-up. In the premenopausal women, the baseline P1NP was significantly lower in DTC patients than in the controls. The LS-BMD, FN-BMD, and TH-BMD in DTC patients were all higher than those in controls at 1-year follow-up. The difference in FN-BMD was not significant after adjusting for baseline P1NP. In the postmenopausal women, no differences in BMD and BTMs were observed between DTC patients and controls at the 1-year and 2-year follow-up.

CONCLUSION

Our study indicated that postoperative 1-year TSH suppressive therapy did not show detrimental effects on BMD and BTMs in men, premenopausal, and postmenopausal DTC patients. The 2-year postoperative TSH suppressive therapy did not lead to additional loss of bone mass in postmenopausal DTC patients.

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

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.

Bone geometry in older adults with subclinical hypothyroidism upon levothyroxine therapy: A nested study within a randomized placebo controlled trial

The effect of levothyroxine (LT4) therapy for subclinical hypothyroidism (SHypo) on appendicular bone geometry and volumetric density has so far not been studied. In a nested study within the randomized, placebo-controlled Thyroid Hormone Replacement for Subclinical Hypothyroidism (TRUST) trial, we assessed the effect of LT4 therapy on bone geometry as measured by peripheral quantitative computed tomography (pQCT). In the TRUST trial, community-dwelling adults aged ≥65 years with SHypo were randomized to LT4 with dose titration vs. placebo with mock titration. We analyzed data from participants enrolled at the TRUST site in Bern, Switzerland who had bone pQCT measured at baseline and at 1 to 2 years follow-up. The primary outcomes were the annual percentage changes of radius and tibia epi- and diaphysis bone geometry (total and cortical cross-sectional area (CSA) and cortical thickness), and of volumetric bone mineral density (bone mineral content (BMC) and total, trabecular and cortical volumetric bone mineral density (vBMD)). We performed linear regression of the annual percentage changes adjusted for sex, LT4 dose at randomization and muscle cross-sectional area. The 98 included participants had a mean age of 73.9 (±SD 5.4) years, 45.9% were women, and 12% had osteoporosis. They were randomized to placebo (n = 48) or LT4 (n = 50). Annual changes in BMC and vBMD were similar between placebo and LT4-treated groups, without significant difference in bone geometry or volumetric bone mineral density changes, neither at the diaphysis, nor at the epiphysis. For example, in the placebo group, epiphyseal BMC (radius) decreased by a mean 0.2% per year, with a similar decrease of 0.5% per year in the LT4 group (between-group difference in %ΔBMC 0.3, 95% CI -0.70 to 1.21, p = 0.91). Compared to placebo, LT4 therapy for an average 14 months had no significant effect on bone mass, bone geometry and volumetric density in older adults with subclinical hypothyroidism. TRIAL REGISTRATION: The trial was registered on ClinicalTrials.gov numbers NCT01660126 (TRUST Thyroid trial) and NCT02491008 (Skeletal outcomes).

Bone-density testing interval and transition to osteoporosis in differentiated thyroid carcinoma patients on TSH suppression therapy

OBJECTIVE

Thyrotropin (TSH) suppression therapy is a standard treatment after surgery for differentiated thyroid carcinoma (DTC). It may be associated with osteoporosis in postmenopausal women. However, there are no guidelines for bone mineral density (BMD) testing intervals to screen for osteoporosis in these patients. Therefore, we evaluated the timing of repeated BMD testing in DTC patients with TSH suppression according to baseline T-scores.

DESIGN, PATIENTS, AND MEASUREMENT

We retrospectively evaluated 658 DTC patients who underwent BMD testing more than twice between January 2007 and January 2020. A 1:3 propensity score matching was conducted to compare the timing of repeated BMD tests between the DTC and non-DTC groups. We stratified the participants into four groups based on their baseline T-scores: normal (-1.00 or higher), mild osteopenia (-1.01 to -1.49), moderate osteopenia (-1.50 to -1.99), and severe osteopenia (-2.00 to -2.49). Additionally, the 10% of patients in each group that transitioned to osteoporosis were analysed.

RESULTS

The estimated BMD testing interval for 10% of patients who developed osteoporosis was 85 months for patients with initially mild osteopenia, 65 months for those with moderate osteopenia, and 15 months for those with severe osteopenia in the DTC group. In the non-DTC group, the testing intervals for mild, moderate, and severe osteopenia were 98, 57, and 13 months, respectively. On multivariate analysis, baseline T-score (mild osteopenia: hazard ratio [HR] 5.91, p = .105; moderate osteopenia: HR, 25.27, p = .02; and severe osteopenia: HR, 134.82, p < .001) and duration of TSH suppression (tertile 2: HR, 2.25, p = .005; Tertile 3: 1.78, p = .033) were independent risk factors for osteoporosis in the DTC group.

CONCLUSION

This study provides guidance for the timing of repeated BMD tests in women over 50 years of age with TSH suppression. The rescreening interval for BMD testing can be modified based on the baseline T-score. The appropriate BMD testing intervals in female DTC patients were similar to those in non-DTC females.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

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).

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.

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.

Biochemical bone turnover markers in hormonal disorders in adults: a narrative review

BACKGROUND

Hormonal disorders are often associated with abnormal levels of bone turnover markers (BTMs). N-terminal propeptide of type I procollagen (PINP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX-I) are the reference markers of bone formation and bone resorption, respectively.

METHODS

A comprehensive literature search within the MEDLINE and Web of Science databases was performed.

RESULTS

Acromegaly is associated with higher BTM levels, which decrease during the remission after treatment. Adult-onset growth hormone deficiency is often associated with decreased BTM levels. Growth hormone replacement therapy stimulates bone turnover and increases BTM levels. Hypothyroidism is characterized by general slowing of bone metabolism which is reflected by lower BTM levels. The replacement thyroid hormone therapy increases the bone turnover rate and BTM levels increase. Patients with thyroid cancer receive a suppressive dose of thyroid hormones and may have slightly elevated BTM levels. Patients with overt hyperthyroidism had higher BTM levels and anti-thyroid therapy induces a rapid decrease in the BTM levels. Patients with overt primary hyperparathyroidism have higher BTM levels, whereas those with asymptomatic and normocalcemic hyperparathyroidism usually have normal BTM levels. Hypoparathyroidism is characterized by slightly decreased BTM levels. Cushing's syndrome is characterized consistently by markedly decreased osteocalcin concentration, whereas data on other BTMs are discordant.

CONCLUSIONS

BTMs help us to better understand mechanisms of the impact of hormonal disorders and their treatment on bone metabolism. However, it is unknown whether BTMs may be used to monitor the effect of their treatments on bone in the clinical practice.

Analysis of the strategy of LT4 prescribing and TSH monitoring for thyroid carcinoma after lobectomy

Background

Thyrotropin (TSH) suppression is a critical step in the management of differentiated thyroid carcinoma (DTC). The objectives of this study were to evaluate changes in TSH levels and a strategy of initial levothyroxine (LT4) supplementation for TSH suppression in low-risk differentiated thyroid carcinoma (lr-DTC) patients after lobectomy.

Methods

One hundred and ten patients with lr-DTC who received lobectomy were enrolled. Each of the patients was given 50 µg LT4 immediately after lobectomy and were retrospectively analyzed to evaluate the initial dose of LT4 suppression during the first year of follow-up. Risk factors influencing the TSH trend were also evaluated.

Results

Median TSH levels decreased significantly after lobectomy and the initiation of LT4 suppression and were stable from 3 to 12 months. Three months after lobectomy, 44.9% of patients fell into the newly recommended first TSH goal (0.35 to 2.0 mIU/L). Insufficient suppression (≥2.0 mIU/L) and oversuppression (<0.35 mIU/L) was observed in 9.4% and 45.8% of the patients, respectively. Preoperative TSH ≥2.0 mIU/L and the coexistence of Hashimoto thyroiditis (HT) were risk factors influencing the TSH trend.

Conclusions

The monitoring of TSH could start from 3 months after lobectomy. An initial dose (50 µg) of LT4 could be adequate for initial suppression therapy in most patients. However, individual adjustment of the first dose may be necessary based on preoperative TSH concentration and the presence of HT.

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.

Postoperative Thyroid-Stimulating Hormone Levels Did Not Affect Recurrence after Thyroid Lobectomy in Patients with Papillary Thyroid Cancer

BACKGROUND

Thyroid-stimulating hormone (TSH) suppression is recommended for patients who undergo thyroidectomy for differentiated thyroid cancer (DTC). However, the impact of TSH suppression on clinical outcomes in low-risk DTC remains uncertain. Therefore, we investigated the effects of postoperative TSH levels on recurrence in patients with low-risk DTC after thyroid lobectomy.

METHODS

Patients (n=1,528) who underwent thyroid lobectomy for papillary thyroid carcinoma between 2000 and 2012 were included in this study. According to the mean and dominant TSH values during the entire follow-up period or 5 years, patients were divided into four groups (<0.5, 0.5 to 1.9, 2.0 to 4.4, and ≥4.5 mIU/L). Recurrence-free survival was compared among the groups.

RESULTS

During the 5.6 years of follow-up, 21 patients (1.4%) experienced recurrence. Mean TSH levels were within the recommended low-normal range (0.5 to 1.9 mIU/L) during the total follow-up period or 5 years in 38.1% or 36.0% of patients. The mean and dominant TSH values did not affect recurrence-free survival. Adjustment for other risk factors did not alter the results.

CONCLUSION

Serum TSH levels did not affect short-term recurrence in patients with low-risk DTC after thyroid lobectomy. TSH suppression should be conducted more selectively.

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.

Influence of Thyroid-stimulating Hormone Suppression Therapy on Bone Mineral Density in Patients with Differentiated Thyroid Cancer: A Meta-analysis

Background

The effects of subclinical hyperthyroidism on bone mineral density (BMD) induced by thyroid-stimulating hormone (TSH) suppression therapy in patients with differentiated thyroid cancer (DTC) remains unclear. We conducted a meta-analysis to determine the influence of TSH suppression therapy on BMD.

Methods

We performed a systematic search to identify studies which included BMD measurement of femoral neck, total hip or lumbar spine in patients on TSH suppression therapy for DTC. Main outcome measures were difference of BMD of femoral neck, total hip or lumbar spine measured by dual energy X-ray absorptiometry between patients and controls.

Results

A systematic search yielded a total of 11 published controlled cross-sectional studies (including about 571 patients and 836 controls). TSH suppression therapy was associated with the lower BMD of total hip (weighted mean difference [WMD], -0.023; 95% confidence interval [CI], -0.047 to 0.000; P=0.050) and spine (WMD, -0.041; 95% CI, -0.057 to -0.026; P<0.001) in postmenopausal women with DTC, while it was not associated with that in premenopausal women and men with DTC.

Conclusions

Although the included studies were limited by small numbers, results suggested possible association between chronic TSH suppression therapy and the lower BMD of spine and total hip in postmenopausal women (but not in premenopausal women and men) with DTC. A large, well-designed study with long-term follow-up would provide further insight into the influence of TSH suppression therapy and loss of BMD.

Effects of thyrotropin suppression on lumbar bone mineral density in postmenopausal women with differentiated thyroid carcinoma

Purpose

The aim of this study was to evaluate the effect of postoperative thyroid-stimulating hormone suppression (TSHS) on bone mineral density (BMD) in Chinese postmenopausal women with differentiated thyroid carcinoma (DTC).

Patients and methods

A total of 225 postmenopausal women with DTC who had received TSHS were included in the study. Postmenopausal women with postoperative DTC undergoing thyroid residual ablation or metastasis treatment between 2009 and 2015 were enrolled and followed up for 2 years. They were divided into two groups: TSHS group (median thyroid-stimulating hormone [TSH] <0.3 μIU/mL) and postmenopausal control group (median TSH >0.3 μIU/mL). Lumbar 1–4 BMD levels were measured by a dual-energy X-ray absorptiometry (DXA) at baseline and 6, 12 and 24 months. All patients had calcium and vitamin D supplementation. The diagnosis of osteopenia (−1 SD > T >−2.5 SD) and osteoporosis (T <−2.5 SD) was made according to WHO guidelines.

Results

Thyroid cancers included 211 papillary carcinomas and 14 follicular carcinomas. One hundred and fifty-four patients were in the TSHS group, and 71 patients were in the non-suppressed TSH group (postmenopausal controls). No significant differences were found in the BMD of the lumbar spine between baseline and after 6, 12 and 24 months, pre and post treatment in TSHS and non-suppressed TSH patients. Compared with pre-TSHS, there was a reduction in the BMD of 1.9% in the lumbar spine at the 2-year follow-up. Significant difference in the number of osteopenia and osteoporosis patients at 24 months (χ²=2.88, P=0.004) was found between the TSHS (103/152) and postmenopausal control (32/68) groups. TSHS is not a significant risk of bone loss, but it is the incidence of osteopenia in postmenopausal women with DTC.

Conclusion

Our 2-year follow-up data indicated that TSHS had little effect on BMD in postmenopausal women with DTC. Large population with at least 5-year follow-up should be further investigated. BMD in postmenopausal women with DTC should be followed up regularly.

Brain to bone: What is the contribution of the brain to skeletal homeostasis?

The brain, which governs most, if not all, physiological functions in the body, from the complexities of cognition, learning and memory, to the regulation of basal body temperature, heart rate and breathing, has long been known to affect skeletal health. In particular, the hypothalamus - located at the base of the brain in close proximity to the medial eminence, where the blood-brain-barrier is not as tight as in other regions of the brain but rather "leaky", due to fenestrated capillaries - is exposed to a variety of circulating body cues, such as nutrients (glucose, fatty acids, amino acids), and hormones (insulin, glucagon, leptin, adiponectin) [1-3].Information collected from the body via these peripheral cues is integrated by hypothalamic sensing neurons and glial cells [4-7], which express receptors for these nutrients and hormones, transforming these cues into physiological outputs. Interestingly, many of the same molecules, including leptin, adiponectin and insulin, regulate both energy and skeletal homeostasis. Moreover, they act on a common set of hypothalamic nuclei and their residing neurons, activating endocrine and neuronal systems, which ultimately fine-tune the body to new physiological states. This review will focus exclusively on the brain-to-bone pathway, highlighting the most important anatomical sites within the brain, which are known to affect bone, but not covering the input pathways and molecules informing the brain of the energy and bone metabolic status, covered elsewhere [8-10]. The discussion in each section will present side by side the metabolic and bone-related functions of hypothalamic nuclei, in an attempt to answer some of the long-standing questions of whether energy is affected by bone remodeling and homeostasis and vice versa.

Low trabecular bone score in postmenopausal women with differentiated thyroid carcinoma after long-term TSH suppressive therapy

The effect of thyroid suppression therapy (TST) on trabecular bone scores (TBS) and bone mineral density (BMD) in thyroidectomized women with differentiated thyroid carcinoma (DTC) on long-term follow-up is presently not conclusive.

PATIENTS AND METHODS

We carried out a study in 61 premenopausal and 84 postmenopausal Caucasian women with DTC. Serum biochemistry, bone markers, TBS, BMD, and bone fractures were evaluated 1-3 months post surgery and after a median follow-up of 10 years.

RESULTS

In the final study, patients belonged to Group I Premenopausal (n = 14) who remained in this status; Group II Premenopausal who became postmenopausal (n = 47); Group III patients who were and continued as postmenopausal (n = 84). Baseline premenopausal patients had a normal TBS mean value of 1.39 ± 0.14 significantly higher than that found in postmenopausal 1.31 ± 0.12 (p = 001). In the final study, premenopausal patients continued to have a normal TBS of 1.46 ± 0.08 compared to the significantly lower value of postmenopausal patients 1.25 ± 0.11 (p = 0.0009). Lumbar BMD (L-BMD) loss after the long-term study was significant in Group II (0.99 g/cm² ± 0.13 vs. 0.91 ± 0.12 g/cm², p < 0.0001) and there was a slight, but not significant, bone loss in Group I (1.00 ± 0.12 vs. 0.98 ± 0.11, p = 0.1936) and in Group III (0.86 ± 0.12 vs. 0.84 ± 0.15, p = 0.1924) compared with baseline values.

CONCLUSION

Longer-term suppression therapy in female patients with DTC did not increase significantly the risk of bone loss, although we found in postmenopausal patients deterioration of bone microarchitecture. TBS study should be considered in the evaluation of postmenopausal DTC patients on long-term DTC for the evaluation of the risk of fractures.

High Prevalence of Radiological Vertebral Fractures in Women on Thyroid-Stimulating Hormone-Suppressive Therapy for Thyroid Carcinoma

CONTEXT

Bone loss and nonvertebral fractures have been reported in patients with differentiated thyroid carcinoma (DTC) undergoing thyroid-stimulating hormone (TSH) suppressive therapy. Radiological vertebral fractures (VFs) are an early and clinically crucial marker of bone fragility.

OBJECTIVE AND DESIGN

A cross-sectional study to evaluate the prevalence and determinants of radiological VFs in women receiving l-thyroxine (L-T4) therapy for DTC.

PATIENTS AND INTERVENTIONS

A total of 179 consecutive women (median age, 59 years; n = 178 postmenopausal) who had undergone thyroidectomy for DTC and were currently receiving L-T4 were evaluated for radiological VFs and bone mineral density (BMD). There were three TSH target levels [<0.5 mU/L, group 1 (n = 83); 0.5 to 1.0 mU/L, group 2 (n = 50); >1.0 mU/L, group 3 (n = 46)].

RESULTS

VFs were found in 51 patients (28.5%), with significantly (P < 0.001) higher prevalence in group 1 (44.6%) as compared with group 2 (24.0%) and group 3 (4.3%). VF prevalence was not significantly different among patients in group 1 with normal BMD, osteopenia, or osteoporosis, whereas in groups 2 and 3, VFs were more frequent in patients with osteoporosis than in those with either osteopenia or normal BMD. In the whole population, VFs were significantly and independently associated with TSH level <1.0 mU/L; densitometric diagnosis of osteoporosis at lumbar spine, femoral neck, or total hip; age of patients; and duration of L-T4 therapy.

CONCLUSION

The prevalence of VFs was high in women with DTC who were undergoing long-term, suppressive L-T4 therapy.

Case report: fast reversal of severe osteoporosis after correction of excessive levothyroxine treatment and long-term follow-up

This case report describes a 38-year-old woman, who presented with bilateral femoral stress fractures and osteoporosis after years of excessive levothyroxine treatment. Her bone health was restored rapidly and long-lasting with the reduction of levothyroxine dosage. No bone-active treatment was warranted.

INTRODUCTION

Hyperthyroidism is a known risk factor for osteoporosis and fractures. Recent studies on patients with serum thyrotropin-suppressive therapy have not, however, indicated adverse effects on bone during long-term follow-up.

METHODS

This case report describes long-term follow-up data of a clinically euthyreoid patient, who developed symptomatic osteoporosis due to excessive levothyroxine treatment.

RESULTS

After correction of levothyroxine dosage, her bone mineral density (BMD) and previously elevated serum osteocalcin levels normalized rapidly and she remained free from fractures during 23 years of follow-up over menopause.

CONCLUSION

Excessive TSH suppression contributed to the secondary osteoporosis in this patient; BMD normalized after dose reduction of levothyroxine and no fractures occurred during 23 years' follow-up. Some patients develop severe osteoporosis if they are over-substituted with levothyroxine, and decent follow-up of patients with levothyroxine supplementation is mandatory.

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.

The natural history and hip geometric changes of primary hyperparathyroidism without parathyroid surgery

There have been few reports on changes in bone geometry in asymptomatic patients with primary hyperparathyroidism (PHPT) not treated surgically. We reviewed the records concerning biochemical parameters, bone mineral density (BMD), and hip geometry in 119 PHPT patients who did not undergo parathyroidectomy, followed up at one of three hospitals affiliated to Seoul National University from 1997 to 2013. We examined biochemical parameters over 7 years and BMD and hip geometry over 5 years of follow-up. We further compared hip geometry and BMD derived from dual-energy X-ray absorptiometry (DXA) between patients and age- and sex-matched controls. The median follow-up duration of 56 patients for whom surgery was not indicated was 33.9 months (range 11.2-131.2 months), and 19.6 % of these patients had disease progression during follow-up. Serum calcium levels remained stable for 7 years in all 119 patients. From a comparison of the PHPT patients for whom surgery was not indicated with controls, both male and postmenopausal female patients had significantly lower hip axis length (P < 0.001), cross-sectional moment of inertia (P < 0.001), cross-sectional area (P < 0.001), and section modulus (P < 0.001). In addition, cortical thickness was significantly decreased at 5 years compared with individual baseline values (P = 0.003). However, there was no significant change in BMD for the duration of the 5-year follow-up. DXA-derived geometry can detect skeletal change in asymptomatic PHPT patients for whom surgery is not indicated, supporting the concept that even mild PHPT can eventually compromise the cortical bones. Hip geometry is a potential tool for monitoring skeletal complication in asymptomatic PHPT patients.

Pituitary-bone connection in skeletal regulation

Pituitary hormones have traditionally been thought to exert specific, but limited function on target tissues. More recently, the discovery of these hormones and their receptors in organs such as the skeleton suggests that pituitary hormones have more ubiquitous functions. Here, we discuss the interaction of growth hormone (GH), follicle stimulating hormone (FSH), thyroid stimulating hormone (TSH), adrenocorticotrophic hormone (ACTH), prolactin, oxytocin and arginine vasopressin (AVP) with bone. The direct skeletal action of pituitary hormones therefore provides new insights and therapeutic opportunities for metabolic bone diseases, prominently osteoporosis.

Low Normal TSH levels are Associated with Impaired BMD and Hip Geometry in the Elderly

Subclinical hyperthyroidism is known to be associated with the risk of fractures in elderly people. However, there are few studies assessing whether low normal thyroid-stimulating hormone (TSH) levels affect bone density and geometry. Here, we aimed to assess the influence of the TSH level on bone mineral density (BMD) and geometry in elderly euthyroid subjects. This was a cross-sectional cohort study. A total of 343 men and 674 women with euthyroidism were included and analyzed separately. The subjects were divided into tertiles based on the serum TSH level. The BMD and geometry were measured using dual-energy X-ray absorptiometry and a hip structural analysis program. Multiple regression analysis was used to compute the odds ratios of osteoporosis in the lower TSH tertile group and the association between geometry parameters and the TSH level. We found that the femoral neck and total hip BMDs were lower in the lower TSH tertile group. In women, the cross-sectional area and cortical thickness of the femur were negatively associated with the TSH level in all three regions (the narrow neck, intertrochanter, and femoral shaft); however, in men, these geometry parameters were significantly associated with the TSH level only in the intertrochanter region. The buckling ratio, a bone geometry parameter representing cortical instability, was significantly higher in the lower TSH tertile group in all three regions in women, but not in men. Our results indicated that lower TSH levels in the euthyroid range are related to lower BMD and weaker femoral structure in elderly women.

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.

MECHANISMS IN ENDOCRINOLOGY: Impact of isolated TSH levels in and out of normal range on different tissues

Routine treatment of thyroid cancer (TC) includes long-term suppression of TSH. The necessity of this treatment in low- and intermediate-risk patients as well as the extent of TSH suppression is currently under discussion. A literature search was performed to illustrate the role of TSH in extrathyroidal cells and to identify potential reasons for different effects of exogenously suppressed and endogenously low TSH levels. Although adverse effects of subnormal and supranormal TSH blood levels on heart and brain have not been consistently found, studies show a clear negative effect of suppressed TSH levels on bone mineral density. Experimental data also support an important role of TSH in the immune system. The ability of levothyroxine (l-T4) to regulate TSH levels and triiodothyronine levels in a physiological manner is limited. Reduction of circadian changes in TSH levels, decrease of thyroid hormone-binding proteins, prevention of potential compensatory increases of TSH levels (e.g., in old age), and unresponsiveness of TSH-producing cells to TRH on l-T4 treatment might cause adverse effects of suppressed TSH levels. In view of the adverse effects of aggressive TSH suppression, achieving the suggested levels of TSH between 0.9 and 1 mU/l in the treatment of low-to-intermediate risk TC patients appears justified.

Effect of Thyrotropin Suppression Therapy on Bone in Thyroid Cancer Patients

BACKGROUND

The thyroid cancer incidence is rising. Despite current guidelines, controversy exists regarding the degree and duration of thyrotropin suppression therapy. Also, its potential skeletal effects remain a concern to physicians caring for thyroid cancer patients. We conducted a review of published data to evaluate existing studies focusing on the skeletal effects of thyrotropin suppression therapy in thyroid cancer patients.

MATERIALS AND METHODS

A systematic search of the PubMed, Ovid/Medline, and Cochrane Central Register of Controlled Trials databases was conducted. The retained studies were evaluated for methodological quality, and the study populations were categorized into premenopausal women, postmenopausal women, and men.

RESULTS

Twenty-five pertinent studies were included. Seven studies were longitudinal and 18 were cross-sectional. Of the 25 included studies, 13 were assigned an excellent methodological quality score. Three of 5 longitudinal studies and 3 of 13 cross-sectional studies reported decreased bone mineral density (BMD) in premenopausal women; 2 of 4 longitudinal studies and 5 of 13 cross-sectional studies reported decreased BMD in postmenopausal women. The remaining studies showed no effect on BMD. The only longitudinal study of men showed bone mass loss; however, cross-sectional studies of men did not demonstrate a similar effect.

CONCLUSION

Studies to date have yielded conflicting results on the skeletal effects of thyrotropin suppression therapy and a knowledge gap remains, especially for older adults and men. Existing data should be cautiously interpreted because of the variable quality and heterogeneity. Identifying groups at risk of adverse effects from thyrotropin suppression therapy will be instrumental to providing focused and tailored thyroid cancer treatment.

IMPLICATIONS FOR PRACTICE

The standard treatment for thyroid cancer includes total thyroidectomy with or without radioactive iodine ablation, often followed by thyrotropin suppression therapy. Despite current guidelines, controversy exists regarding the degree and duration of thyrotropin suppression therapy, and discordant results have been reported on its adverse effects on bone. The present review provides physicians with existing data on the skeletal effects of thyrotropin suppression therapy, highlighting the need for further research to identify the groups at risk of adverse skeletal effects. This knowledge will aid in developing tailored thyroid cancer treatment.

[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.

Radioiodine Treatment and Thyroid Hormone Suppression Therapy for Differentiated Thyroid Carcinoma: Adverse Effects Support the Trend toward Less Aggressive Treatment for Low-Risk Patients

Over the past decades, the incidence of differentiated thyroid carcinoma (DTC) has steadily increased, with especially a growing number of low-risk patients. Whereas DTC used to be treated rather aggressively, it is now acknowledged that aggressive treatment does not affect outcome for low-risk patients and that it can induce adverse effects. In this review an overview of the most clinically relevant adverse effects of radioiodine treatment and thyroid hormone suppression therapy (THST) is presented, and the trend toward less aggressive treatment for low-risk patients is outlined. Salivary gland dysfunction occurs in roughly 30% of patients, and is probably due to the concentration of radioiodine in the salivary glands by the sodium/iodide symporter. Beta radiation from radioiodine can result in sialoadenitis and eventually fibrosis and loss of salivary function. Furthermore, patients can experience bone marrow dysfunction following radioiodine treatment. Although this is in general subclinical and transient, patients that receive very high cumulative radioiodine doses may be at risk for more severe bone marrow dysfunction. THST can induce adverse cardiovascular effects in patients with DTC, such as diastolic and systolic dysfunction, and also adverse vascular and prothrombotic effects have been described. Finally, the effects of THST on bone formation and resorption are outlined; especially postmenopausal women with DTC on THST seem to be at risk of bone loss. In the past years, advances have been made in preventing low-risk patients from being overtreated. Improved biomarkers are still needed to further optimize risk stratification and personalize medicine.