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

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.

Exploring the oral-gut microbiota during thyroid cancer: Factors affecting the thyroid functions and cancer development

Thyroid cancer (TC) is categorized into papillary, follicular, medullary, and anaplastic. The TC is increasing in several countries, including China, the United States, the United Kingdom, Canada, France, Australia, Germany, Japan, Spain, and Italy. Thus, this review comprehensively covers the factors that affect thyroid gland function, TC types, risk factors, and symptoms. Lifestyle factors (such as nutrient consumption and smoking) and pollutants (such as chemicals and heavy metals) increased the thyroid-stimulating hormone (TSH) levels which are directly related to TC prevalence. The conventional and recent TC treatments are also highlighted. The role of the oral and gut microbiota as well as the application of probiotics on TC are also discussed. The variations in the composition of oral and gut microbes influence the thyroid function indirectly through alteration in metabolites (such as short-chain fatty acids) that are eminent for cellular energy metabolism. Maintenance of healthy gut and oral microbiota can help in regulating thyroid function by regulating iodine uptake. Oral or gut microbial dysbiosis can be considered as an early diagnosis factor or TC marker. High TSH during TC can increase the oral microbial diversity while disrupting the high ratio of Firmicutes and Bacteroidetes in the gut. Supplementation of probiotics as an adjuvant in TC treatment is beneficial. However, needs more extensive research to explore the direct effect of probiotics on thyroid function.

Thyrotropin inhibits osteogenic differentiation of human periodontal ligament stem cells

BACKGROUND AND OBJECTIVE

Periodontal ligament stem cells (PDLSCs) are derived from the periodontal ligament and have the characteristics of pluripotent differentiation, including osteogenesis, and are one of the important seed cells in oral tissue engineering. Thyrotropin (TSH) has been shown to regulate bone metabolism independently of thyroid hormone, including the fate of osteoblasts and osteoclasts, but whether it affects osteogenic differentiation of PDLSCs is unknown.

MATERIALS AND METHODS

PDLSCs were isolated and cultured from human periodontal ligament and grown in osteogenic medium (containing sodium β-glycerophosphate, ascorbic acid, and dexamethasone). Recombinant human TSH was added to the culture medium. Osteogenic differentiation of PDLSCs was assessed after 14 days by staining with alkaline phosphatase and alizarin red and by detection of osteogenic differentiation genes. Differentially expressed genes (DEGs) in PDLSCs under TSH were detected by high-throughput sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyzed the biological functions and signaling pathways involved in DEGs.

RESULTS

We found that osteogenic differentiation of PDLSCs was significantly inhibited in the presence of TSH: including decreased calcium nodule formation, decreased alkaline phosphatase levels, and decreased collagen synthesis. Using high-throughput sequencing, we found changes in the expression of some osteogenesis-related genes, which may be the reason that TSH inhibits osteogenic differentiation of PDLSCs.

CONCLUSION

Unless TSH is ≥10 mU/L, patients with subclinical hypothyroidism usually do not undergo thyroxine supplementation therapy. However, in this work, we found that elevated TSH inhibited the osteogenic differentiation of PDLSCs. Therefore, correction of TSH levels in patients with subclinical hypothyroidism may be beneficial to improve orthodontic, implant, and periodontitis outcomes in these patients.

Independent Skeletal Actions of Pituitary Hormones

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

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

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

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

CONTEXT

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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.

Measurements of Bone Health after Thyroid-Stimulating Suppression Therapy in Postmenopausal Women with Differentiated Thyroid Carcinoma: Bone Mineral Density versus the Trabecular Bone Score

Background: Thyroid-stimulating hormone (TSH) suppression therapy is an important treatment modality for differentiated thyroid carcinoma (DTC), but it increases fracture risk. The aim of this study was to evaluate changes in bone mineral density (BMD) and trabecular bone score (TBS) in postmenopausal DTC patients receiving TSH suppression therapy. Methods: A total of 410 postmenopausal DTC patients who underwent thyroidectomy and had at least two dual-energy X-ray absorptiometry measurements, including a preoperative measurement, were included. Patients who had osteoporosis medication for more than 1 year were classified as ‘patients with osteoporosis’. Results: In patients without osteoporosis, the change in %BMD was similar between TSH suppression (−) and (+) groups, while the decrease in %TBS was significantly greater in the TSH suppression (+) group than that of the TSH suppression (−) group. The relative risk of vertebral fracture was decreased by TBS changes but not by BMD changes. In patients with osteoporosis, both BMD and TBS showed significant increases in the TSH suppression (−) group but not in TSH suppression (+) group. At year 4, TBS was significantly lower in the TSH suppression (+) group than that in the TSH suppression (−) group, while BMD showed no difference between groups. Conclusions: TBS may better reflect bone health than BMD in postmenopausal DTC patients with TSH suppression therapy.

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 tamoxifen with or without gonadotropin-releasing hormone analog on DXA values in women with breast cancer

The purpose of this study was to compare the changes in DXA values including trabecular bone score (TBS) and bone mineral density (BMD) of lumbar spine (LS) and femur according to the hormone therapies including tamoxifen (TMXF) treatment with or without gonadotropin releasing hormone analog (GnRH analog) in women with breast cancer. We enrolled 119 women with breast cancer who had undergone breast-conserving surgery or mastectomy followed by TMXF treatment for postmenopausal women (TMXF group, n = 63, 52.9%) or by combination therapy of TMXF combined with GnRH analog for premenopausal women (TMXF + GnRH group, n = 56, 47.1%) from December 2013 to December 2017. The median follow-up period was 13 months (interquartile range [IQR], 12.0–14.75) for TMXF group and 13.5 months (IQR, 12.00–16.00) for TMXF + GnRH group, respectively. Patients did not receive bone-modifying therapy. The baseline dual-energy X-ray absorptiometry (DXA) scan before breast cancer surgery and follow-up DXA during hormone therapy. Comparing the first and follow-up DXA results, BMD in LS were significantly decreased in both TMXF (P < 0.001, mean difference: − 0.06) and TMXF + GnRH (P < 0.001, mean difference: − 0.09) groups. BMD values of femoral neck (P = 0.0011, mean difference: − 0.01) and total femur (P < 0.001, mean difference: − 0.03) was significantly changed between the baseline and follow-up DXA in TMXF + RnRH group. In the TMX group, a significant changed occurred in the BMD in total femur (P < 0.001, mean difference: − 0.030) but not the BMD of femoral neck (P = 0.095, mean difference: − 0.007). Regarding TBS, no significant change was found in the TMXF (P = 0.574, mean difference: − 0.004) group, whereas there was a significant decrease in TBS in the TMXF + GnRH (P < 0.001, mean difference: − 0.02) group during follow-up. TBS is more sensitive in reflecting the bone microarchitecture changes by TMXF or GnRH agonist in breast cancer patients than BMD. This finding demonstrates that TBS can be a useful parameter to detect bone microarchitectural changes in clinical applications.

Thyroid Hormone Diseases and Osteoporosis

Thyroid hormones are essential for normal skeletal development and normal bone metabolism in adults but can have detrimental effects on bone structures in states of thyroid dysfunction. Untreated severe hyperthyroidism influences the degree of bone mass and increases the probability of high bone turnover osteoporosis. Subclinical hyperthyroidism, defined as low thyrotropin (TSH) and free hormones within the reference range, is a subtler disease, often asymptomatic, and the diagnosis is incidentally made during screening exams. However, more recent data suggest that this clinical condition may affect bone metabolism resulting in decreased bone mineral density (BMD) and increased risk of fracture, particularly in postmenopausal women. The main causes of exogenous subclinical hyperthyroidism are inappropriate replacement dose of thyroxin and TSH suppressive L-thyroxine doses in the therapy of benign thyroid nodules and thyroid carcinoma. Available data similarly suggest that a long-term TSH suppressive dose of thyroxin may decrease BMD and may induce an increased risk of fracture. These effects are particularly observed in postmenopausal women but are less evident in premenopausal women. Overt hypothyroidism is known to lower bone turnover by reducing both osteoclastic bone resorption and osteoblastic activity. These changes in bone metabolism would result in an increase in bone mineralization. At the moment, there are no clear data that demonstrate any relationship between BMD in adults and hypothyroidism. Despite these clinical evidences, the cellular and molecular actions of thyroid hormones on bone structures are not complete clear.

Heterogenous biochemical expression of hormone activity in subclinical/overt hyperthyroidism and exogenous thyrotoxicosis

Background

Subclinical hyperthyroidism/thyrotoxicosis originates from different causes and clinical conditions, sharing the laboratory constellation of a suppressed TSH in the presence of thyroid hormone concentrations within the reference range.

Aim

Presentation of hyperthyroidism can manifest itself in several ways. We questioned whether there is either a consistent biochemical equivalence of thyroid hormone response to these diagnostic categories, or a high degree of heterogeneity may exist both within and between the different clinical manifestations.

Methods

This secondary analysis of a former prospective cross-sectional trial involved 461 patients with untreated thyroid autonomy, Graves’ disease or on levothyroxine (LT4) after thyroidectomy for thyroid carcinoma. TSH response and biochemical equilibria between TSH and thyroid hormones were contrasted between endogenous hyperthyroidism and thyrotoxicosis (LT4 overdose).

Results

Concentrations of FT4, FT3, TSH, deiodinase activity and BMI differed by diagnostic category. Over various TSH strata, FT4 concentrations were significantly higher in LT4-treated thyroid carcinoma patients, compared to the untreated diseases, though FT3 levels remained comparable. They were concentrated in the upper FT4- but low deiodinase range, distinguishing them from patients with thyroid autonomy and Graves’ disease. In exogenous thyrotoxicosis, TSH and FT3 were less responsive to FT4 concentrations approaching its upper normal/hyperthyroid range.

Conclusions

The presence or lack of TSH feedforward activity determines the system response in the thyroid-active (hyperthyroidism) and no-thyroid response to treatment (thyrotoxicosis). This rules out a consistent thread of thyroid hormone response running through the different diagnostic categories. TSH measurements should therefore be interpreted conditionally and differently in subclinical hyperthyroidism and thyrotoxicosis.

Skeletal Effects of Levothyroxine for Subclinical Hypothyroidism in Older Adults: A TRUST Randomized Trial Nested Study

CONTEXT

Both thyroid dysfunction and levothyroxine (LT4) therapy have been associated with bone loss, but studies on the effect of LT4 for subclinical hypothyroidism (SHypo) on bone yielded conflicting results.

OBJECTIVE

To assess the effect of LT4 treatment on bone mineral density (BMD), Trabecular Bone Score (TBS), and bone turnover markers (BTMs) in older adults with SHypo.

DESIGN AND INTERVENTION

Planned nested substudy of the double-blind placebo-controlled TRUST trial. Participants with SHypo were randomized to LT4 with dose titration versus placebo with computerized mock titration.

SETTING AND PARTICIPANTS

196 community-dwelling adults over 65 years enrolled at the Swiss TRUST sites had baseline and 1-year follow-up bone examinations; 4 participants withdrew due to adverse events not related to treatment.

MAIN OUTCOME MEASURES

One-year percentage changes of BMD, TBS, and 2 serum BTMs (serum CTX-1 [sCTX] and procollagen type 1 N-terminal polypeptide [P1NP]). Student's t-test for unadjusted analyses and linear regression adjusted for clinical center and sex were performed.

RESULTS

Mean age was 74.3 years ± 5.7, 45.4% were women, and 19.6% were osteoporotic. The unadjusted 1-year change in lumbar spine BMD was similar between LT4 (+0.8%) and placebo-treated groups (-0.6%; between-groups difference +1.4%: 95% confidence interval [CI] -0.1 to 2.9, P = .059). Likewise, there were no between-group differences in 1-year change in TBS (-1.3%: 95% CI -3.1 to 0.6, P = .19), total hip BMD (-0.2%: 95% CI -1.1 to 0.1, P = .61), or BTMs levels (sCTX +24.1%: 95% CI -7.9 to 56.2, P = .14), or after adjustment for clinical centers and sex.

CONCLUSIONS

Over 1-year levothyroxine had no effect on bone health in older adults with SHypo.

REGISTRATION

ClinicalTrial.gov NCT01660126 and NCT02491008.

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.