Early postmenopausal bone loss in hyperthyroidism

Bone cell-specific deletion of thyroid hormone transporter Mct8 distinctly regulates bone volume in young versus adult male mice

Thyroid hormones are critical regulators of bone metabolism. Their cellular import is guided through transporter proteins, including the monocarboxylate transporter 8 (MCT8). Conditional Mct8 knockout in osteoblast and osteoclast precursors leads to trabecular bone gain in 12-week-old male mice. Given that thyroid hormones regulate both skeletal development and bone maintenance, we investigated the effect of bone cell-specific Mct8 deletion in 6-week-old (young) and 24-week-old (adult) male mice. Mct8 ablation in osteoclast precursors led to trabecular bone gain at the spine in 6-week-old animals compared to age-matched controls, whereas adult animals displayed a shift towards trabecular bone loss in both femur and vertebra. Mct8 deficiency in osteoprogenitors increased osteoblast numbers and trabecular bone mass at the spine of young mice, without skeletal differences between adult knockout mice and littermate controls. In contrast, young mice lacking Mct8 in late osteoblasts/osteocytes exhibited lower trabecular bone volume at the spine and femur compared to respective controls, but no differences were detected at 24 weeks of age. In vitro studies of osteoblasts with Dmp1-Cre promotor driven Mct8 deletion showed no significant alterations of osteogenic marker gene expression and mineralization capacity suggesting that MCT8 is not crucial for osteoblast maturation. Overall, we observed mild effects with conditional Mct8 knockout on bone microarchitecture and bone turnover especially during growth implying a secondary role for MCT8 as a thyroid hormone transporter in bone.

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.

Bone health in children with long-term idiopathic subclinical hypothyroidism

Background

Subclinical hypothyroidism (SH) is a relatively common condition characterized by a mild persistent thyroid failure. The management of children with SH is still a controversial issue and the decision to treat with L-thyroxine represents a clinical dilemma. Thyroid hormone and TSH play an important role in skeletal growth and bone mineral homeostasis.

Aim

To evaluate whether untreated idiopathic SH may affect bone health in childhood and to compare two different diagnostic tools such as dual-energy X-ray densitometry (DXA) and quantitative ultrasound (QUS).

Patients and Methods

Twenty-five children and adolescents (11 males) aged 9.8 ± 3.5 years (range 4.2-18.7) with untreated idiopathic SH were enrolled in the study. SH was diagnosed on the basis of normal FT4 levels with TSH concentrations between 4.2 and 10 mU/l. Children have been followed for 3.3 ± 0.3 years from the time of SH diagnosis. Twenty-five healthy children, age- and sex-matched, were enrolled as controls. Patients and controls underwent DXA to evaluate lumbar spine bone mineral density (BMD) and QUS at proximal phalanges of the non-dominant hand to assess bone quality, measured as amplitude-dependent speed of sound (Ad-SoS) and bone transmission time (BTT).

Results

Mean BMD Z-score was −0.4 ± 1.36 in patients and −0.2 ± 1.2 in controls. Mean Ad-SoS Z-score was 0.01 ± 1.0 in patients and 0.1 ± 1.2 in controls and mean BTT Z-score was −0.03 ± 0.8 and 0.04 ± 1.1 respectively. All values were within the normal range, both in patients and in controls. There were no statistically significant differences between the two groups.

Conclusion

Bone health, evaluated by lumbar spine DXA and phalangeal QUS, is not impaired in our children, despite long-term duration of idiopathic SH. Data about bone status provided by QUS are comparable to those provided by DXA. Therefore, QUS may represent a good, cheaper and safe screening test for bone evaluation in children with SH.

[Clinical practice guidelines for evaluation and treatment of osteoporosis associated to endocrine and nutritional conditions. Bone Metabolism Working Group of the Spanish Society of Endocrinology]

OBJECTIVE

To provide practical recommendations for evaluation and treatment of osteoporosis associated to endocrine diseases and nutritional conditions.

PARTICIPANTS

Members of the Bone Metabolism Working Group of the Spanish Society of Endocrinology, a methodologist, and a documentalist.

METHODS

Recommendations were formulated according to the GRADE system (Grading of Recommendations, Assessment, Development, and Evaluation) to describe both the strength of recommendations and the quality of evidence. A systematic search was made in MEDLINE (Pubmed), using the following terms associated to the name of each condition: AND "osteoporosis", "fractures", "bone mineral density", and "treatment". Papers in English with publication date before 18 October 2011 were included. Current evidence for each disease was reviewed by two group members, and doubts related to the review process or development of recommendations were resolved by the methodologist. Finally, recommendations were discussed in a meeting of the Working Group.

CONCLUSIONS

The document provides evidence-based practical recommendations for evaluation and management of endocrine and nutritional diseases associated to low bone mass or an increased risk of fracture. For each disease, the associated risk of low bone mass and fragility fractures is given, recommendations for bone mass assessment are provided, and treatment options that have shown to be effective for increasing bone mass and/or to decreasing fragility fractures are listed.

Efeitos sítio-ósseo dependentes no fêmur e vértebra de ratas com disfunções tireoidianas

OBJETIVO: Avaliar as diferenças sítio-ósseo dependentes no efeito das disfunções tireoidianas no fêmur e vértebras lombares de ratas. MÉTODOS: 33 ratas Wistar com dois meses de idade foram distribuídas em três grupos: eutireoideas (controle), hipotireoideas e hipertireoideas. Após 90 dias de tratamento para indução do hipo e hipertireoidismo, as ratas foram eutanasiadas, o sangue foi colhido para dosagem de T4 livre e os fêmures e as vértebras lombares (L1-L3) foram descalcificados e processados para análise da porcentagem de tecido ósseo trabecular. RESULTADOS: O grupo hipertireoideo apresentou porcentagem de tecido ósseo trabecular significativamente mais elevada na metáfise femoral, em comparação ao controle. Mas o hipertireoidismo não alterou a porcentagem de tecido ósseo trabecular na vértebra. O hipotireoidismo reduziu significativamente a porcentagem de tecido ósseo trabecular em comparação aos demais grupos nos segmentos 1-3 das vértebras lombares, mas não alterou a porcentagem de tecido ósseo trabecular no fêmur. CONCLUSÃO: O efeito do hipotireoidismo e do hipertireoidismo sobre a histomorfometria óssea é diferente e dependente do sítio ósseo.

Calcium homeostasis in thyroid disease in dogs and cats

Hyperthyroidism is the most common endocrine disorder of cats, and hypothyroidism is the most common endocrine disorder of dogs. Little is known regarding the effects of hyperthyroidism, hypothyroidism, or treatment of these disorders on calcium metabolism in the dog or cat, however, especially any potential effects on bone. With better diagnostic tools, better treatments, and increased longevity of pets, the clinical impact of thyroid disorders on calcium metabolism and bone may be uncovered.

Negative correlation between bone mineral density and TSH receptor antibodies in male patients with untreated Graves' disease

INTRODUCTION

Although it has been established that hyperthyroidism leads to reduced bone mineral density (BMD), with accelerated bone turnover promoting bone resorption in female patients, there is a dearth of data for male patients with hyperthyroidism. This study evaluated BMD and bone metabolism in male patients with Graves' disease.

METHODS

The study included 56 Japanese male patients with newly diagnosed Graves' disease and 34 normal Japanese male control subjects of similar age and body mass index. We used dual energy x-ray absorptiometry to measure BMD at sites with different cortical/cancellous bone ratios (lumbar spine, femoral neck, and distal radius).

RESULTS

At the lumbar spine and the distal radius, BMD and T-scores were significantly lower for patients than for controls. At the femoral neck, on the other hand, the same values were relatively, but not significantly, lower in patients than in controls. However, Z-scores at all three sites were significantly lower for patients than for controls. The Z -score at the distal radius of patients was significantly lower than that at their lumbar spine and femoral neck. In addition, Z-score at the distal radius correlated negatively with age, free thyroxine, thyroid stimulating hormone receptor antibodies, thyroid stimulating antibody, and urinary N-terminal telopeptide of type I collagen normalized by creatinine.

CONCLUSIONS

These results indicate a high prevalence of cortical bone loss in male patients with Graves' disease, especially elderly patients. We conclude that BMD measurement is crucial in all Graves' disease patients regardless of their gender and that the radial BMD as well as BMD at the lumbar spine and femoral neck should be monitored to effectively prevent bone loss and subsequent fracture.

Effects on Bone Mineral Density by Treatment of Benign Nodular Goiter with Mildly Suppressive Doses of L-Thyroxine in a Cohort Women Study

OBJECTIVES

Thyroid diseases and their treatment may influence the osseous system. The influence that prolonged suppressive L-thyroxine (LT4) therapy may have on inducing subclinical hyperthyroidism on bone metabolism is still a matter of debate. The aim of the present study was to assess the effects of chronic LT4 treatment at mildly inhibiting serum thyroid-stimulating hormone (TSH) doses on bone mineral density (BMD) and biochemical bone remodeling markers in a cohort of women with benign nodular goiter, and to verify the efficacy of the treatment on nodule size.

SUBJECTS AND STUDY DESIGN

A total of 200 euthyroid Caucasian women with nodular goiter (age 52.1 +/- 9; 80 pre- and 120 postmenopausal) were enrolled: 96 had been treated with LT4 for at least 3 years and a matched group of 104 had untreated goiter. LT4 therapy was given at a dose sufficient to reduce TSH under the lower limit of the normal range (0.27-4.20 microIU/ml) without suppressing it below the limit of assay sensitivity (0.005 microIU/ml) and maintaining normal serum values of free triiodothyronine (FT3) and free thyroxine (FT4). The adequacy of the dose was evaluated on the basis of serum TSH levels. The osteopenic effect of LT4 treatment was evaluated directly by total body and lumbar spine dual-energy X-ray absorptiometry (DEXA) and indirectly by biochemical parameters (alkaline phosphatase, osteocalcin, calcium, parathyroid hormone) at the baseline and throughout the follow-up. The efficacy of LT4 schedule on thyroid nodule size was assessed on the basis of the ultrasonographic evaluation.

RESULTS

Mineralometric data showed no significant difference between BMD values for treated and untreated patients in both pre- and postmenopausal status. In all patients, serum markers of bone turnover were in the normal range, with no differences in the treated and control groups. The TSH concentrations were significantly lower in treated than in untreated patients (p < 0.0001); FT3 and FT4 were in the normal range for all patients. Evaluation of nodule size during follow-up showed a reduction of > or = 30% in 32 of 96 treated patients (33.3%) versus none in those untreated, whilst nodule size remained unmodified in 60 treated patients (62.5%) versus 35 (33.6%) in those untreated, and an increase in nodule size and/or development of new nodules was found in 4 treated patients (4.2%) versus 69 of the 104 untreated patients (66.3%).

CONCLUSIONS

This study suggests that at slightly suppressing TSH doses, LT4 therapy has no adverse effects on BMD in both pre- and postmenopausal women, while having an efficacy on nodule size comparable with that reported using an LT4 schedule able to maintain TSH near or below the assay sensitivity limit.

Reduced bone mass detected by bone quantitative ultrasonometry and DEXA in pre- and postmenopausal women with endogenous subclinical hyperthyroidism

BACKGROUND

Although overt hyperthyroidism is a well known cause of bone loss, systemic effects of subclinical hyperthyroidism (SH) are still a matter of debate.

OBJECTIVE

The aim of this cross-sectional study was to evaluate the effect of endogenous SH on bone in relation to the menopausal status.

METHODS

Bone mass and turnover were assessed in a group of 60 patients with endogenous SH due to multinodular goitre; 30 of them were premenopausal and 30 early postmenopausal (mean age, 40.9 +/- 7.3 and 57.7 +/- 6.75, respectively). Sixty healthy women matched for age-, BMI- and menopausal status served as controls. Three different skeletal sites were evaluated using two different techniques: lumbar spine and femoral neck were assessed by DEXA whereas the proximal phalanges were evaluated by quantitative ultrasonometry (QUS), measuring the amplitude-dependent speed of sound (Ad-SoS). Serum osteocalcin and urinary deoxypyridinoline (DPD) were also determined as markers of bone turnover.

RESULTS

A significant decrease was found in femoral BMD (P < 0.05) and phalangeal Ad-SoS (P < 0.001) in pre- and postmenopausal patients compared to controls, being greater in those postmenopausal. Lumbar BMD was decreased only in postmenopausal patients (P < 0.05). Bone turnover markers were higher in patients than in controls and in post- than in the premenopausal ones. A significant negative correlation was found between femoral BMD, Ad-SoS and serum free T3 levels, the latter considered a marker of disease activity.

CONCLUSIONS

A significant increase in bone turnover markers and a decrease in bone mass was found in women affected by endogenous SH, being greater in early postmenopausal patients. Cortical rich bone was mainly affected. Both QUS and the conventional DEXA technique were equally able to determine bone density decrease related to mild thyroid hormone excess and sexual hormone decrease.

Ostéoporoses secondaires en médecine interne

INTRODUCTION

The term 'primary' osteoporosis refers to osteoporosis that results from the involutional losses associated with aging and, in women, additional losses related to natural menopause. Osteoporosis that is caused or exacerbated by other disorders or medication exposures is referred to as 'secondary' osteoporosis.

CURRENT KNOWLEDGE AND KEY POINTS

This article describes the major causes and provides a framework for the diagnostic investigation of patients with suspected of having secondary osteoporosis. There are numerous causes of secondary bone loss, including endocrine disorders, disorders of the gastrointestinal or biliary tract, rheumatic diseases, haematological diseases, immobilization, adverse effects of drug therapy, and a wide miscellaneous group.

FUTURE PERSPECTIVES

Secondary osteoporosis is potentially reversible during the treatment of the underlying disease. It must be identified and induce a symptomatic treatment in all cases plus an etiologic treatment when possible.

[Effects of hyperthyroidism on bone mass in women of reproductive age]

INTRODUCTION

Hyperthyroidism is one of the most frequent endocrinopathies in women of reproductive age. Consequently, increased risk of osteoporosis may be expected.

MATERIAL AND METHODS

The research has included a group of 30 hyperthyroid women and a control group of 30 healthy women of reproductive age. Age and some clinical characteristics were analyzed, as well as some anthropometric parameters. Bone mass parameters were determined by measuring bone mineral density using ultrasound devices (SAHARA-Hologic).

RESULTS

Bone mass parameters in hyperthyroid women are significantly lower than in controls (BUA: 63.25+/-12.17; 69.73+/-10.02 dB/MHz respectively; SOS: 1523.90+/-24.47; 1540.19+/-26.59 m/s respec. QUI/STIFF 79.78+/-13.95; 89.09+/-13.99% respec.) Duration of hyperthyroidism affects bone density and reduces it.

DISCUSSION

Obtained results were expected, having in mind that hyperthyroidism is a condition characterized by increased bone catabolic rate. Also, negative correlation between the duration of hyperthyroidism and bone mass parameters (BUA, SOS) was expected, because it is logical that consolidation of bone mass in adult life cannot be maintained in circumstances in which metabolic rate is increased. During hyperthyroidism, bone loss is expected. In order to confirm this, future studies of bone markers are necessary.

CONCLUSION

Based on results obtained in the study, the following conclusions were made: hyperthyroidism is accompanied by decreased values of bone mass parameters; this effect depends on duration of hyperthyroidism. We confirmed that hyperthyroidism may be the cause of decrease in bone mass, particularly if it lasts more than a year. To prevent osteoporosis in women of reproductive age with hyperthyroidism and involutional osteoporosis later in life, early diagnosis and effective therapy of hyperthyroidism is imperative.

Hyperthyroidism, bone mineral, and fracture risk--a meta-analysis

This study examined changes in bone mineral and fracture risk after treatment for hyperthyroidism in a meta-analysis. The PubMed and EMBASE were searched using the MESH terms "hyperthyroidism," "bone mineral density" (BMD), and "fracture," resulting in retrieval of 289 references. Twenty references describing BMD and five describing fracture risk were included in the meta-analysis. BMD was significantly decreased in patients with untreated hyperthyroidism. Upon treatment BMD increased significantly and reversed to normal levels with a temporary increase above normal levels 1-4 years after diagnosis. The risk of hip fractures increased significantly with age at diagnosis of hyperthyroidism. The hip fracture risk after diagnosis predicted from studies on BMD was close to that observed in clinical studies comparing fracture risk in hyperthyroid patients with normal controls. Thus BMD is significantly decreased and fracture risk increased in untreated hyperthyroidism. Upon normalization of the hyperthyroid state BMD return to normal even though no specific antiosteoporotic measures are taken other than normalizing the hyperthyroid state.