The characteristics of osteoporotic patients in Graves' disease patients newly diagnosed after menopause: a prospective observational study

Wnt Inhibitors and Bone Mineral Density in Patients with Graves' Disease Treated with Antithyroid Drugs: A Preliminary Prospective Study

This study aimed to investigate the association of Wnt inhibitors with thyroid hormones, bone turnover markers, and bone mineral density (BMD) in patients with newly diagnosed Graves’ disease (GD) at the beginning of the antithyroid treatment and after a follow-up period of one year. The study included 37 patients with newly diagnosed GD who were treated with antithyroid drugs (ATD). At baseline and after one year, thyroid hormones and thyroid-stimulating hormone (TSH), serum concentrations of sclerostin, and Dickkopf-1 (DKK1) were measured by an enzyme-linked immunosorbent assay (ELISA). In addition, BMD was measured by dual-energy X-ray absorptiometry (DXA), and markers of bone turnover including osteocalcin (OC), beta-cross laps (β-CTX), and deoxypyridinoline (DPD) were determined. After one year of ATD therapy sclerostin levels were significantly decreased (p < 0.001), whereas DKK1 levels were significantly increased (p = 0.01). In addition, BMD of the lumbar spine, total hip, and femoral neck was significantly improved (p < 0.001), accompanied by an increase in OC, β-CTX, and DPD concentrations (p < 0.001). At baseline, sclerostin levels were positively associated with free triiodothyronine (FT3). Following ATD therapy, a positive correlation was observed between FT3 and DKK1 (p = 0.003), whereas a negative correlation was found between TSH and DKK1 (p = 0.04). Correlation analysis demonstrated no association of the sclerostin and DKK1 with other bone remodeling biomarkers OC, β-CTX, or DPD. Also, no significant correlation between sclerostin or DKK1 and T-score or BMD of the lumbar spine, hip, and femoral neck was observed at both time points. Conclusion: Observed differences in sclerostin and DKK1 serum following GD treatment indicate involvement of Wnt inhibitors in the etiopathogenesis of bone loss associated with hyperthyroidism. Furthermore, both sclerostin and DKK1 are involved in the reversal of changes in bone metabolism following ATD therapy, thus presenting potentially valuable bone remodeling markers worth further investigation.

Effect of Thyroxine and Thyrotropin on Bone Mineral Density in Postmenopausal Women: A Systematic Review

The effect of thyroid hormones on bone mineral density in postmenopausal women has been reported but is not completely established. To better understand this relationship, this systematic review of the reported association, differences, and effects of thyroxine and/or thyrotropin levels on bone mineral density was conducted. An electronic literature search was conducted on MEDLINE, PMC, Google Scholar, Cochrane Library, and Science Direct from inception to April 2022; 20 studies were identified which include five quasi-experimental studies, three community cohort studies, and 12 hospital-based cross-sectional studies. Following an extensive evaluation, it was difficult to conclusively determine the association or effect of thyroxine or thyrotropin levels on bone mineral density in postmenopausal women. It is therefore suggested to conduct additional non-randomized or randomized control studies on this topic for the benefit of postmenopausal women. Particular attention should be given to the adjustment of age, body mass index, smoking status, alcohol consumption, and dietary calcium in future research on this topic for rigorous analysis.

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.

Graves' disease and vertebral fracture: Possible pathogenic link in postmenopausal women

BACKGROUND AND OBJECTIVE

Thyrotoxicosis is associated with accelerated bone turnover and increases the risk of fractures and osteoporosis. Graves' disease is the most common cause of hyperthyroidism. However, studies that examined risk factors associated with fragility fractures only in patients with Graves' disease are limited. Here, we investigated whether the risk of vertebral fracture (VF) of postmenopausal Graves' disease patients is high and tried to identify the risk factors for VF in that population.

DESIGN AND METHODS

Forty-three postmenopausal women with Graves' disease were enrolled. Physical and biochemical indices, thyroid indices and bone mineral density (BMD) were measured, and lateral X-rays were obtained to evaluate VFs. Age- and sex-matched healthy individuals were enrolled as the control group (n = 86).

RESULTS

The prevalence of VFs (35% vs 17%, P < .05), osteoporosis (63% vs 33%, P < .01) and severe osteoporosis (40% vs 17%, P < .01) was significantly higher in the Graves' disease group. Although there was no significant difference in either thyroid hormone levels or the positive ratio of thyroid antibodies, the prevalence of thyroid-stimulating antibody (TSAb) was significantly higher in Graves' disease patients with VF compared to without (100% vs 68%, P < .05). Multivariate logistic regression analyses adjusted for age identified Graves' disease as being associated with the presence of VFs (OR 2.72, 95% CI: 1.13-6.54, P < .05) in postmenopausal women.

CONCLUSIONS

Postmenopausal Graves' disease patients had high risks of VF and severe osteoporosis. TSAb could be involved as a risk factor for VF in postmenopausal Graves' disease.

The importance of estrogen for bone protection in experimental hyperthyroidism in human osteoblasts

Triiodothyronine (T₃) and estrogen (E₂) play important roles in the bone remodeling process and signaling of receptor activator of the nuclear factor-kappa β (RANKL) and osteoprotegerin (OPG) expressed by osteoblasts. However, little is known of the molecular action of these hormones in conditions of hyperthyroidism and associated E₂ in human cells.

AIMS

This study evaluated the effects of the physiological concentration of E₂ (10 nM), alone or in association with physiological (1 nM) and supraphysiological (10 nM) concentrations of T₃, on RANKL and OPG gene expression in human osteoblasts.

MAIN METHODS

Alkaline phosphatase and osteocalcin assays were performed to verify the presence of mature osteoblasts. After mimicking the experimental hyperthyroidism in osteoblasts untreated or treated with E₂, RANKL and OPG gene expression was analyzed by real-time PCR and protein expression by western Blot and ELISA. Alizarin Red staining analyzed the amount of bone matrix after hormonal treatments.

KEY FINDINGS

E₂ enhanced the gene expression of OPG when associated with 1 nM and 10 nM T₃. E₂ was able to restore the bone matrix after an initial decrease using 1 nM and 10 nM T₃. The protective effect of E₂ on the RANKL and OPG signaling pathway was demonstrated. E2 restored the bone matrix induced by experimental hyperthyroidism.

SIGNIFICANCE

The data highlight the importance of E₂ to maintain OPG expression and osteoblast activity against possible loss of bone mass, especially in conditions where T₃ is in excess.

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.