Longitudinal changes in lumbar bone density among thyrotoxic patients after attainment of euthyroidism

Bone turnover decreases and bone structure improves during treatment with weekly high-dose methylprednisolone for 12 weeks in Graves' orbitopathy

PURPOSE

Weekly treatment with the intravenous glucocorticoid methylprednisolone for 12 weeks is mainstay in the treatment of Graves' orbitopathy but may decrease bone mass and impair bone structure. We therefore investigated bone turnover, -mass and -structure during the treatment cause in these patients.

METHODS

We included 32 patients with Graves' orbitopathy scheduled for treatment with methylprednisolone. Bone turnover and thyroid function was measured at baseline and after 3, 9, 12, and 24 weeks, bone mineral density (BMD) was measured using dual x-ray absorptiometry at baseline and after 12 and 24 weeks, and bone structure was measured using high-resolution peripheral quantitative computed tomography at baseline and after 12 weeks.

RESULTS

Bone turnover and tri-iodothyronine decreased throughout the study. Cortical volumetric BMD at both the radius and tibia increased significantly by 0.98 ± 0.38% (p = 0.01) and 1.35 ± 0.50% (p = 0.01), respectively and cortical porosity at both the radius and tibia decreased significantly by -7.67 ± 3.13% (p = 0.04) and -3.30 ± 2.17% (p = 0.04), respectively. Bone mineral density was stable during the first 12 weeks but increased significantly by 2.26 ± 3.61% at the femoral neck (p < 0.01) and by 2.24 ± 4.24% at the total hip towards week 24 (p = 0.02). Stratified analyses suggested that remission of hyperthyroidism was the most important determinant of changes in bone turnover, bone mass and structure.

CONCLUSION

During a 12-week course of high-dose intravenous methylprednisolone bone turnover and cortical porosity decreased and during 24 weeks follow up bone mineral density increased. In terms of bone, methylprednisolone therefore is a safe treatment for Graves' orbitopathy.

Changes in bone mineral density and trabecular bone score in Graves' disease patients after anti-thyroid therapy

Objective

The purpose of this study was to evaluate changes in bone quantity based on bone mineral density (BMD) and bone quality based on trabecular bone score (TBS) in Graves' disease patients after anti-thyroid therapy.

Research design and method

This retrospective study included premenopausal female and male patients with Graves' disease who received BMD measurement more than two times during treatment. BMD and thyroid function tests with free thyroxine (FT4), total triiodothyronine (T3), thyroid stimulating hormone (TSH), and TSH receptor antibody (TRAb) levels were collected two times during follow-up. TBS was calculated using TBS insight^® software (version 2.1) from dual-energy X-ray absorptiometry images.

Results

Thirty Graves' disease patients (17 males, 56%; 13 premenopausal females, 44%) with a mean age of 35.3 ± 9.9 years were included. The mean follow-up period was 20.7 ± 8.5 months. The median levels of FT4, TSH and TRAb improved at follow-up [2.55 ng/dL (Interquartile range (IQR) 2.07–3.78) to 1.28 ng/dL (IQR 1.23–1.39), 0.015 mIU/L (IQR 0.01–0.04) to 0.89 mIU/L (IQR 0.35–1.55), 17.0 IU/L (IQR 5.0–40.3) to 5.0 IU/L (5.0–6.0), respectively; p < 0.001]. Median BMD (lumbar spine) values also improved from 1.118 g/cm² (IQR 1.000–1.119) to 1.167 g/cm² (IQR 1.050–1.219) (p = 0.001) at follow-up. TBS increased from 1.377 (IQR 1.299–1.422) to 1.390 (IQR 1.327–1.430) after treatment (p = 0.038).

Conclusion

Both bone quality and density improved after anti-thyroid treatment in premenopausal female and male Graves' disease patients.

Negative correlation between bone mineral density and TSH receptor antibodies in long-term euthyroid postmenopausal women with treated Graves' disease

BACKGROUND

Thyrotoxicosis is a cause of secondary osteoporosis. High concentrations of triiodotironine (T3) in Graves' disease stimulate bone turnover, but it is unclear if euthyroidism will always normalize bone metabolism. Thyrotropin (TSH) is known to affect directly the bone metabolism through the TSH receptor and TSH receptor antibodies (TRAb) may have an important role in bone turn-over.The aim of our study was to determine, in pre and postmenopausal euthyroidism patients with previous overt hyperthyroidism due to Graves' disease the bone mineral density (BMD) as well as factors that could affect BMD in each group, including TRAb.

METHODS

Cross-sectional, non-interventional study. Fifty-seven patients with previous hyperthyroidism due to Graves' disease (premenopausal: 30, postmenopausal: 27) that remained euthyroid for at least 6 months prior to study were included and compared with fifty- two matched respective controls. Thyrotoxine (T4), TSH, TRAb and BMD were measured.

RESULTS

Only euthyroid postmenopausal patients with a history of hyperthyroidism due to Graves' disease showed lower whole body BMD than matched controls. The BMD expressed as Z-score was less in whole body and lumbar spine in postmenopausal in relation to premenopausal women with previous overt hyperthyroidism due to Graves' disease.In the postmenopausal patients, the Z-score of lumbar spine BMD correlated negatively with TRAb (r = -0,53, p < 0.008), positively with the time of evolution of the disease (r = +0.42, p < 0.032) and positively with the time of euthyroidism (r = + 0.50, p < 0.008), but neither with serum T4 nor TSH. In a multiple regression analysis TRAb was the only significant independent variable in relation to lumbar spine BMD (F = 3. 90, p < 0.01).

CONCLUSIONS

In euthyroid women with a history of Graves' hyperthyroidism, BMD was only affected in the postmenopausal group. The negative correlation of Z-score of lumbar spine BMD with TRAb suggests that this antibody may affect the bone metabolism.

Metabolic and clinical consequences of hyperthyroidism on bone density

In 1891, Von Recklinghausen first established the association between the development of osteoporosis in the presence of overt hyperthyroidism. Subsequent reports have demonstrated that BMD loss is common in frank hyperthyroidism, and, to a lesser extent, in subclinical presentations. With the introduction of antithyroid medication in the 1940s to control biochemical hyperthyroidism, the accompanying bone disease became less clinically apparent as hyperthyroidism was more successfully treated medically. Consequently, the impact of the above normal thyroid hormones in the pathogenesis of osteoporosis may be presently underrecognized due to the widespread effective treatments. This review aims to present the current knowledge of the consequences of hyperthyroidism on bone metabolism. The vast number of recent papers touching on this topic highlights the recognized impact of this common medical condition on bone health. Our focus in this review was to search for answers to the following questions. What is the mechanisms of action of thyroid hormones on bone metabolism? What are the clinical consequences of hyperthyroidism on BMD and fracture risk? What differences are there between men and women with thyroid disease and how does menopause change the clinical outcomes? Lastly, we report how different treatments for hyperthyroidism benefit thyroid hormone-induced osteoporosis.

Bone mineral density in patients of Graves disease pre- & post-treatment in a predominantly vitamin D deficient population

Background & objectives:

Hyperthyroidism causes bone loss, and its treatment may restore bone mass, however, concomitant vitamin D deficiency may prevent this. We undertook this study to measure the bone mineral density (BMD) 25 (OH) vitamin D levels in patients with Graves disease in our population which is predominently vitamin D deficient and how we change with when patients become euthyroid.

Methods:

The biochemical, thyroid functions, serum vitamin D levels and BMD were estimated in 80 consecutive patients with Graves and 80 euthyroid controls. Patients were treated and rendered euthyroid. Fifty four completed one year, and 27 completed two years of follow up.

Results:

Patients had significant reduced BMD during hyperthyroid state compared to normal healthy controls. The mean vitamin D levels at baseline were in the insufficient range both patients (12.67±6.24 ng/ml) and controls (10.99±7.05 ng/ml). The BMD improved at all sites with antithyroid treatment. But, the BMD adjusted for body mass index (BMI) and age at all sites showed significant decrease with time.

Interpretation & conclusions:

Age and body mass index positively correlated with BMD. There was improvement in absolute BMD of patients at one and two years of follow up. When the BMD was adjusted for age and BMI, there was a decrease in BMD at one year which was less in the second year including that the damage in BMD caused by thyroid hormone excess is not made up even after two years of patient being euthyroid. Whether vitamin D replacement would change this needs to be studied.

Diseases affecting bone quality: beyond osteoporosis

BACKGROUND

Bone quantity, quality, and turnover contribute to whole bone strength. Although bone mineral density, or bone quantity, is associated with increased fracture risk, less is known about bone quality. Various conditions, including disorders of mineral homeostasis, disorders in bone remodeling, collagen disorders, and drugs, affect bone quality.

QUESTIONS/PURPOSES

The objectives of this review are to (1) identify the conditions and diseases that could adversely affect bone quality besides osteoporosis, and (2) evaluate how these conditions influence bone quality.

METHODS

We searched PubMed using the keywords "causes" combined with "secondary osteoporosis" or "fragility fracture." After identifying 20 disorders/conditions, we subsequently searched each condition to evaluate its effect on bone quality.

RESULTS

Many disorders or conditions have an effect on bone metabolism, leading to fragility fractures. These disorders include abnormalities that disrupt mineral homeostasis, lead to an alteration of the mineralization process, and ultimately reduce bone strength. The balance between bone formation and resorption is also essential to prevent microdamage accumulation and maintain proper material and structural integrity of the bone. As a result, diseases that alter the bone turnover process lead to a reduction of bone strength. Because Type I collagen is the most abundant protein found in bone, defects in Type I collagen can result in alterations of material property, ultimately leading to fragility fractures. Additionally, some medications can adversely affect bone.

CONCLUSIONS

Recognizing these conditions and diseases and understanding their etiology and pathogenesis is crucial for patient care and maintaining overall bone health.

Can bone loss be reversed by antithyroid drug therapy in premenopausal women with Graves' disease?

Context

Hyperthyroidism can lead to reduced bone mineral density (BMD) and increased fracture risk particularly in postmenopausal women, but the mechanism behind is still unclear.

Objective

Prospective examination of the influence of thyroid hormones and/or thyroid autoantibodies on BMD in premenopause.

Design

We have examined 32 premenopausal women with untreated active Graves' disease from time of diagnosis, during 18 months of antithyroid drug therapy (ATD) and additionally 18 months after discontinuing ATD. Variables of thyroid metabolism, calcium homeostasis and body composition were measured every 3 months. BMD of lumbar spine and femoral neck were measured at baseline, 18 ± 3 and 36 ± 3 months. Data were compared to base line, a sex- and age matched control group and a group of patients with Hashimoto's thyroiditis treated with non-suppressive doses of levothyroxine.

Results

The study showed significantly (p < 0.002) lower BMD in the thyrotoxic state compared to the control group with subsequent significant improvement during 18 ± 3 months of ATD compared to baseline (p < 0.001). However, during the following 18 months after stopping ATD femoral neck BMD decreased again unrelated to age (more than 0.4% per year, p < 0,002). The wellestablished effect of thyrotoxicosis on calcium homeostasis was confirmed. The positive predictor for best BMD was TSH receptor antibodies (TRAb) while free T4 correlated negatively in the thyrotoxic female Graves' patients (p < 0.02 and p < 0.003). In healthy controls and patients with treated Graves' disease both TSH and T4 correlated negatively to the bone mass (BMC) (p < 0.003).

Conclusion

The results indicated a clinically relevant impact of thyroid function on bone modulation also in premenopausal women with Graves' disease, and further indicated the possibility for a direct action of TRAb on bones.

Clinical significance of risedronate for osteoporosis in the initial treatment of male patients with Graves' disease

It has been well established that hyperthyroidism leads to diminished bone mineral density (BMD), and that a previous history of hyperthyroidism remains a risk factor for fractures. However, little is known about how to manage the reduction in BMD caused by hyperthyroidism. The purpose of this study was to evaluate the efficacy of risedronate for the treatment of osteoporosis/osteopenia in patients with Graves' disease (GD). Of 34 Japanese male patients with newly diagnosed GD, 27 with osteoporosis/osteopenia were included in this study. They were randomly divided into two groups by therapeutic regimen. Group A consisted of 14 patients treated with an antithyroid drug and risedronate. Group B consisted of 13 patients treated with the same antithyroid drug only. We used dual-energy X-ray absorptiometry to measure BMD at the lumber spine, femoral neck, and distal radius at baseline, and at 6 and 12 months after the trial. Bone-specific alkaline phosphatase and urinary N-terminal telopeptide of type I collagen normalized by creatinine were significantly more reduced in group A than in group B after both 6 and 12 months. The percentage increases in BMD at the lumbar spine and distal radius were significantly greater in group A than in group B. These beneficial effects of risedronate for patients with osteoporosis/osteopenia caused by GD may lead to a reduced risk of future fractures. We thus conclude that risedronate should be considered for the treatment of decreased bone mass associated with GD.