Negative correlation between the change in bone mineral density and serum osteocalcin in patients with hyperthyroidism

The utility of dried blood spot measurement of bone turnover markers in biological anthropology

OBJECTIVES

Bone is a dynamic organ under continual turnover influenced by life history stage, energy dynamics, diet, climate, and disease. Bone turnover data have enormous potential in biological anthropology for testing evolutionary and biocultural hypotheses, yet few studies have integrated these biomarkers. In the present article we systematically review the current availability, future viability, and applicability of measuring bone turnover markers (BTMs) in dried blood spot (DBS) samples obtained from finger prick whole blood.

METHODS

Our review considers clinical and public health relevance, biomarker stability in DBS, assay availability, and cost. We consider biomarkers of bone formation such as osteocalcin (bone matrix protein), PINP (N-terminal propeptide of type I collagen), and alkaline phosphatase (osteoblast enzyme), as well as biomarkers of bone resorption such as CTX (marker of collagen breakdown) and TRACP5b (tartrate-resistant acid phosphatase 5b; osteoclast enzyme).

RESULTS

Two BTMs have been validated for DBS: osteocalcin (formation) and TRACP5b (resorption). Prime candidates for future development are CTX and PINP, the formation and resorption markers used for clinical monitoring of response to osteoporosis treatment.

CONCLUSION

BTMs are a field-friendly technique for longitudinal monitoring of skeletal biology during growth, reproduction and aging, combining minimized risk to study participants with maximized ease of sample storage and transport. This combination allows new insights into the effects of energy availability, disease, and physical activity level on bone, and questions about bone gain and loss across life history and in response to environmental factors; these issues are important in human biology, paleoanthropology, bioarchaeology, and forensic anthropology.

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.

Hungry Bone Syndrome Secondary to Subtotal Thyroidectomy in A Patient With Thyrotoxicosis

Patients with thyrotoxicosis are prone to transient hypocalcemia after thyroidectomy, which may be due in part to surgical damage to the parathyroid glands. Hungry bone syndrome (HBS) can also cause hypocalcemia after thyroidectomy. HBS is due to increased osteoblast-mediated bone formation activity and normal or decreased bone resorption activity. As HBS is uncommon in patients after thyroidectomy, we herein present a case of hypocalcemia secondary to HBS after subtotal thyroidectomy for thyrotoxicosis in a 25-year-old woman with a two-month history of tingling extremities and carpopedal spasms after subtotal thyroidectomy for thyrotoxicosis. Diagnostic tests showed hypocalcemia and hyperphosphatemia with elevated parathyroid hormone levels and moderately decreased serum 25-hydroxyvitamin D levels. In addition to thyroid hormone replacement therapy, she was given calcitriol and Caltrate D (600 mg calcium plus 125 IU cholecalciferol). After two months of treatment, she no longer had spasms and her paresthesia improved. Meanwhile, serum electrolytes and parathyroid hormone levels had almost returned to the normal ranges. This is a rare case of HBS presented as a complication of subtotal thyroidectomy in a patient with thyrotoxicosis.

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.

A Modest Protective Effect of Thyrotropin against Bone Loss Is Associated with Plasma Triiodothyronine Levels

BACKGROUND

The independent skeletal effect of thyrotropin (thyroid stimulating hormone, TSH) has been suggested in animal studies. However, clinical data on the association between bone loss and variations in TSH levels is inconsistent. This study aimed to investigate the relationship between TSH levels and bone mineral density (BMD).

METHODS

We conducted a cross-sectional study with 37,431 subjects (33,052 cases with euthyroidism and 4,379 cases with subclinical thyroid dysfunction) aged over 35 years. We performed thyroid function tests and measured BMD at the lumbar spine, femur neck, and total hip.

RESULTS

Levels of TSH and T3 were positively correlated in women (r = 0.076, P = 0.001) and uncorrelated in men. In both men and women, TSH levels correlated positively and T3 levels correlated negatively with BMD at all skeletal sites in age and body mass index adjusted analyses. BMD increased steadily with TSH levels from the subclinical hyperthyroid to subclinical hypothyroid range in subjects with T3 levels in the highest tertile (119.5-200.0 ng/dL), but was no longer significant in subjects with lower plasma T3 levels.

CONCLUSIONS

The variations in TSH levels within the euthyroid and subclinical range were positively correlated with BMD in healthy men and women. The negative effect of T3 on BMD appears to be compensated for by increased TSH in subjects with plasma T3 levels in the upper normal range.

The Presence of Thyroid-Stimulation Blocking Antibody Prevents High Bone Turnover in Untreated Premenopausal Patients with Graves' Disease

Osteoporosis-related fractures are one of the complications of Graves’ disease. This study hypothesized that the different actions of thyroid-stimulating hormone receptor (TSHR) antibodies, both stimulating and blocking activities in Graves’ disease patients might oppositely impact bone turnover. Newly diagnosed premenopausal Graves’ disease patients were enrolled (n = 93) and divided into two groups: patients with TSHR antibodies with thyroid-stimulating activity (stimulating activity group, n = 83) and patients with TSHR antibodies with thyroid-stimulating activity combined with blocking activity (blocking activity group, n = 10). From the stimulating activity group, patients who had matched values for free T4 and TSH binding inhibitor immunoglobulin (TBII) to the blocking activity group were further classified as stimulating activity-matched control (n = 11). Bone turnover markers BS-ALP, Osteocalcin, and C-telopeptide were significantly lower in the blocking activity group than in the stimulating activity or stimulating activity-matched control groups. The TBII level showed positive correlations with BS-ALP and osteocalcin levels in the stimulating activity group, while it had a negative correlation with the osteocalcin level in the blocking activity group. In conclusion, the activation of TSHR antibody-activated TSH signaling contributes to high bone turnover, independent of the actions of thyroid hormone, and thyroid-stimulation blocking antibody has protective effects against bone metabolism in Graves’ disease.

Change of Bone Mineral Density and Biochemical Markers of Bone Turnover in Patients on Suppressive Levothyroxine Therapy for Differentiated Thyroid Carcinoma

Untreated hyperthyroidism and high-dose thyroid hormone are associated with osteoporosis, and increased bone mineral density (BMD) has been demonstrated in postmenopausal females with hypoparathyroidism. Studies on the effect of suppressive levothyroxine (LT4) therapy on BMD and bone metabolism after total thyroidectomy in patients with differentiated thyroid carcinoma have presented conflicting results, and few studies in relation to the status of hypoparathyroidism have been studied. One hundred postmenopausal women and 24 premenopausal women on LT4 suppression therapy were included in this study. BMD of lumbar spine and femur and bone turnover markers were measured at the baseline and during the follow-up period up to 18 months using dual energy X-ray absorptiometry. Biochemical marker of bone resorption was measured by urine deoxypyridinoline and bone formation by serum osteocalcin. The age ranged from 36 to 64 years old. Thyroid stimulating hormone (TSH) was suppressed during the study. The results showed that BMD of femur and lumbar spine were not significantly changed in both pre- and postmenopausal women except femur neck in postmenopausal women without hypoparathyroidism. Patients with hypoparathyroidism had higher BMD gain than those without hypoparathyroidism in total hip (1.25 vs. -1.18%, P=0.015). Biochemical markers of bone turnover, serum osteocalcin, and urine deoxypyridinoline did not show significant change. In conclusion, patients with well differentiated thyroid carcinoma are not at a great risk of bone loss after LT4 suppressive therapy. The state of hypoparathyroidism is associated with increased BMD, particularly in postmenopausal women.

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.

Impact of severity, duration, and etiology of hyperthyroidism on bone turnover markers and bone mineral density in men

BACKGROUND

Hyperthyroidism is accompanied by osteoporosis with higher incidence of fracture rates. The present work aimed to study bone status in hyperthyroidism and to elucidate the impact of severity, duration, and etiology of hyperthyroidism on biochemical markers of bone turnover and bone mineral density (BMD).

METHODS

Fifty-two male patients with hyperthyroidism, 31 with Graves' disease (GD) and 21 with toxic multinodular goiter (TNG), with an age ranging from 23 to 65 years were included, together with 25 healthy euthyroid men with matched age as a control group. In addition to full clinical examination, patients and controls were subjected to measurement of BMD using dual-energy X-ray absorptiometery scanning of the lower half of the left radius. Also, some biochemical markers of bone turnover were done for all patients and controls.

RESULTS

Biochemical markers of bone turnover: included serum bone specific alkaline phosphatase, osteocalcin, carboxy terminal telopeptide of type l collagen also, urinary deoxypyridinoline cross-links (DXP), urinary DXP/urinary creatinine ratio and urinary calcium/urinary creatinine ratio were significantly higher in patients with GD and TNG compared to controls (P < 0.01). However, there was non-significant difference in these parameters between GD and TNG patients (P > 0.05). BMD was significantly lower in GD and TNG compared to controls, but the Z-score of BMD at the lower half of the left radius in patients with GD (-1.7 ± 0.5 SD) was not significantly different from those with TNG (-1.6 ± 0.6 SD) (>0.05). There was significant positive correlation between free T3 and free T4 with biochemical markers of bone turnover, but negative correlation between TSH and those biochemical markers of bone turnover. The duration of the thyrotoxic state positively correlated with the assessed bone turnover markers, but it is negatively correlated with the Z-score of BMD in the studied hyperthyroid patients (r = -0.68, P < 0.0001).

CONCLUSION

Men with hyperthyroidism have significant bone loss with higher biochemical markers of bone turnover. The severity and the duration of the thyrotoxic state are directly related to the derangement of biochemical markers of bone turnover and bone loss.

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.

Low cortical bone density measured by computed tomography in children and adolescents with untreated hyperthyroidism

OBJECTIVE

To determine whether increased thyroid hormones levels have an effect on various bone components (cortical vs cancellous bone).

STUDY DESIGN

The anthropometric and 3-dimensional quantitative computed tomography (CT) bone measurements, including bone density (BD), cross-sectional area (CSA) of the lumbar spine and femur, and cortical bone area (CBA) of the femur, of 18 children and adolescents with untreated hyperthyroidism were reviewed and compared with those of age-, sex-, and ethnicity-matched historical controls.

RESULTS

No significant differences in height, weight, body mass index (BMI), or pubertal staging between patients and controls were found. Cortical BD was significantly lower (P < .001) in children and adolescents with hyperthyroidism compared with historical controls. After adjusting for weight and height, no difference in femur CSA between hyperthyroid children and historical controls was evident. No significant correlations among thyroid hormone levels, antithyroid antibody levels, and cortical BD values were found.

CONCLUSIONS

As determined by CT, cortical bone is the preferential site of bone loss in children and adolescents with untreated hyperthyroidism.

Insights into material and structural basis of bone fragility from diseases associated with fractures: how determinants of the biomechanical properties of bone are compromised by disease

Minimal trauma fractures in bone diseases are the result of bone fragility. Rather than considering bone fragility as being the result of a reduced amount of bone, we recognize that bone fragility is the result of changes in the material and structural properties of bone. A better understanding of the contribution of each component of the material composition and structure and how these interact to maintain whole bone strength is obtained by the study of metabolic bone diseases. Disorders of collagen (osteogenesis imperfecta and Paget's disease of bone), mineral content, composition and distribution (fluorosis and osteomalacia); diseases of high remodeling (postmenopausal osteoporosis, hyperparathyroidism, and hyperthyroidism) and low remodeling (osteopetrosis, pycnodysostosis); and other diseases (idiopathic male osteoporosis, corticosteroid-induced osteoporosis) produce abnormalities in the material composition and structure that lead to bone fragility. Observations in patients and in animal models provide insights on the biomechanical consequences of these illnesses and the nature of the qualities of bone that determine its strength.

Relationship between Subclinical Thyroid Dysfunction and Femoral Neck Bone Mineral Density in Women

BACKGROUND

Osteoporosis associated with thyroid dysfunction has been traditionally viewed as a secondary consequence of altered thyroid function, but there was recently a report about the direct effects of thyroid-stimulating hormone (TSH) on bone remodeling, which was mediated via the TSH receptor found on osteoblast and osteoclast precursor cells. Endogenous subclinical thyroid dysfunction seems to be an appropriate model to examine the direct effect of TSH on bone metabolism while ruling out the direct effect of thyroid hormone on bone metabolism. Thus, we aimed to investigate the relationship between subclinical thyroid dysfunction and bone mineral metabolism in women.

METHODS

We enrolled 413 women (mean age: 52.2 +/- 6.6 years) in our study. Serum levels of TSH, free T4 and the biochemical markers of bone turnover were measured by the standard methods. BMD at the lumbar spine and femoral neck were measured by dual energy X-ray absorptiometry.

RESULTS

Femoral neck BMD was significantly reduced both in the subclinical hyperthyroid group and in the subclinical hypothyroid group as compared with the euthyroid group (one-way ANOVA, p <0.001; post-hoc analysis, p = 0.041, p = 0.033). In contrast to the femoral neck BMD, the lumbar spine BMD showed no difference between the two groups. Additionally, serum calcium and alkaline phosphatase levels, urine deoxypyridinoline levels, and urine calcium to creatinine ratio showed no differences between the two groups.

CONCLUSIONS

Women having subclinical hyperthyroidism and women with subclinical hypothyroidsm have reduced femoral neck BMD. Additional studies are required to elucidate the mechanism for this finding.

[Evaluation of bone mineral density in hyperthyroid patients before and after medical therapy]

Osteoporosis is a common complication of hyperthyroidism, but it is not often evaluated. The aim of this study is to examine bone mineral density (BMD) (dual energy X-ray absorptiometry: DEXA) in lumbar spine (L1-L4), femoral neck (FN) and Ward's triangle (TW) in 45 hyperthyroid patients (group A: n 25 active hyperthyroidism, group B: n 20 controlled hyperthyroidism on medical therapy, after a mean of 7 months of euthyroidism), compared to control group (group C: n 22). These 3 groups are adjusted by age, sex, menopausal status and BMI. In hyperthyroid patients (group A), as compared to the control group, we noticed a significant reduction of BMD (z score) in different sites, more markedly in the lumbar spine (p L1-L4: 0,005; p FN: 0,011; p TW: 0,019). In group A, no differences were found between BMD values after adjustment for Z score whatever the menopausal status (p L: 0.12; p FN: 0.33; p TW: 0.09) and degree ofhyperthyroidism (p L: 0.48; p FN: 0.41; p TW: 0.21). The degree of BMD in group B patients was different from that of patients in group A (p L: 0.37; p FN: 0.28; p TW: 0.31). and was significantly lower than in those of group C except for the TW (p L: 0.009; p CF: 0.038; p TW: 0.068). We conclude that it is important to consider that after reaching euthyroidism hyperthyroidism patients present a bone risk.

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.

Exogenous subclinical hyperthyroidism during adolescence: effect on peak bone mass

BACKGROUND

Chronic subclinical hyperthyroidism induced by suppressive doses of L-thyroxine (L-T4) therapy, so-called exogenous subclinical hyperthyroidism, may cause diminished bone mass in postmenopausal women. The effect of subclinical hyperthyroidism during childhood and adolescence on peak bone mass, however, has not been evaluated.

OBJECTIVE

To determine whether exogenous subclinical hyperthyroidism during adolescence, the period of critical bone mass acquisition, would reduce peak bone mass.

PATIENTS AND METHODS

Eighteen female adolescents and young adults with Hashimoto's thyroiditis and euthyroid goiter (aged 22.4 +/- 4.4 years) who had been treated with suppressive doses of L-T4, 127.5 +/- 23.7 microg/day, during adolescence (age at onset of subclinical hyperthyroidism, 14.2 +/- 1.5 years) for 6.3 +/- 3.4 years were enrolled in the study. Twenty-nine healthy female volunteers matched for age, weight, height and body mass index served as the controls. Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry.

RESULTS

BMD of the lumbar spine, radius, Ward's triangle and total body were comparable in the two groups. In contrast, BMD of the femoral neck, trochanter and shaft of patients was slightly higher than those of controls. There were no correlations between BMD values and clinical parameters.

CONCLUSION

Exogenous subclinical hyperthyroidism during adolescence has no demonstrable detrimental effect on peak bone mass attainment.

A clinical and therapeutic approach to thyrotoxicosis with thyroid-stimulating hormone suppression only

Subclinical hyperthyroidism is defined as normal serum free thyroxine (T4) and triiodothyronine (T3) concentrations and persistently suppressed thyroid stimulating hormone (TSH) concentrations. The most common cause of subclinical hyperthyroidism is the use of suppressive doses of L-thyroxine for treatment of hypothyroidism or, less commonly, diffuse nontoxic goiter or thyroid carcinoma (exogenous subclinical hyperthyroidism). Endogenous subclinical hyperthyroidism may be caused by a variety of thyroid disorders that result in overproduction and release of thyroid hormones from the gland with normal/high 24-hour thyroid radioiodine uptake or by inflammation in the thyroid resulting in release of excess thyroid hormones and low 24-hour thyroid radioiodine uptake. Several groups have investigated whether persistent endogenous or exogenous subclinical hyperthyroidism, like overt hyperthyroidism, causes symptoms, adverse effects on the cardiovascular and the skeletal systems, and increased mortality, whether endogenous subclinical hyperthyroidism evolves to overt thyrotoxicosis, and whether or not it should be treated. The present report reviews the most important and recent studies of subclinical hyperthyroidism and attempts to draw conclusions based upon the literature and the authors' experience.

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.

Thyroid hormone excess and bone--a clinical review

During the past several years, studies have suggested that exogenous thyroid hormone may adversely affect bone. In order to address this contention and to put the issue in perspective for clinicians who treat patients with thyroid hormone replacement, the available literature was reviewed, and the various study populations were characterized. Age, gender, and menopausal status of the patient are important factors, as are the indication for thyroid hormone replacement and the extent, duration, and severity of prior hyperthyroidism. Reliable measures of bone mineral density, particularly dual-energy x-ray, absorptiometry have become available, providing a more accurate reflection of this parameter in patients receiving thyroxine therapy in comparison with control subjects. The bulk of evidence indicates that long-term thyroxine therapy is safe if the dose is carefully monitored. Treatment with thyroxine does not produce clinically significant bone disease.

Transient hyperthyroidism after withdrawal of antithyroid drugs in patients with Graves' disease

The development of silent thyroiditis in patients with a history of Graves' disease is common, especially in the postpartum period. We describe herein patients with Graves' disease who developed transient hyperthyroidism but not silent thyroiditis after withdrawal of antithyroid drug (ATD). If such patients are diagnosed as recurrence of Graves' disease, they may receive ATD or radioiodine therapy unnecessarily. We investigated the characteristics of these patients to prevent unnecessary therapy. We retrospectively studied 22 patients with Graves' disease who showed transient thyrotoxicosis after withdrawal of ATD. Two of 22 patients were male and the mean ages (+/- SD) were 33.7 +/- 12.6 yr. We observed these patients for 28.5 +/- 12.8 (mean +/- SD; range 12-53) months after transient thyrotoxicosis, and measured TSH, FT4, and TSH binding inhibitor immunoglobulin in sera. Radioiodine uptake was measured in 6 of them. The radioiodine uptake in the 4 patients was not suppressed (27.5%, 28.0%, 32.7%, 38.1%). These uptake levels indicate that their thyrotoxicosis was not caused by silent thyroiditis. Most of the 22 patients became euthyroid within 6 months. This study suggests a new therapeutic option as follows: in the case of young patients with mild thyrotoxicosis after withdrawal of ATD, physicians should follow them up for one month without medication unless they have unbearable symptoms or complications.

Thyroid hormone stimulates osteoclast differentiation by a mechanism independent of RANKL-RANK interaction

It is well known that thyroid hormone excess causes bone loss. However, the precise mechanism of bone loss by thyroid hormone still remains unclear. When T(3) was added to unfractionated bone cells after degeneration of pre-existent osteoclasts, T(3) (1 pM-100 nM) dose-dependently stimulated osteoclast-like cell formation, irrespective of the presence of indomethacin and IL-6 Ab. T(3) increased the expression of osteoprotegerin (OPG) messenger RNA (mRNA), but not of receptor activator of nuclear factor kappaB ligand (RANKL) in unfractionated bone cells, suggesting that the stimulatory effect of T(3) on osteoclast formation was not mediated by the RANKL/OPG system. We next examined the direct effect of T(3) on osteoclast precursors in the absence of osteoblasts, using hemopoietic blast cells derived from spleen cells. T(3) (1 pM-100 nM) dose-dependently stimulated osteoclast-like cell formation from osteoclast precursors. OPG did not inhibit T(3)-induced osteoclast formation from osteoclast precursor cells. The polymerase chain reaction (PCR) product corresponding in size to the mouse T(3) receptor alpha1 cDNA was detected in osteoclast precursors from mouse hemopoietic blast cells as well as mouse heart and mouse osteoblastic cell line MC3T3-E1 cells, suggesting that T(3) directly stimulated osteoclast-like cell formation from osteoclast precursors in the absence of osteoblasts. Further, T(3) increased the expression of c-Fos mRNA at 15 min and 24 h and Fra-1 mRNA at 2 and 6 h in osteoclast precursors. Consistent with the increased expression of c-Fos mRNA observed by RT-PCR, the activation of c-Fos occurred in osteoclast precursor cells stimulated by T(3), while the activation of neither NF-kappaB nor MAPKs was observed by immunoblot analysis. Antisense oligodeoxynucleotides (as-ODN) complementary to c-Fos mRNA at 1 microM significantly inhibited T(3)-induced osteoclast-like cell formation from osteoclast precursors in the absence of stromal cells while sense-ODN did not affect T(3)-induced osteoclast-like cell formation. These results indicate that T(3) directly stimulates osteoclast differentiation at least in part by up-regulation of c-fos protein in osteoclast precursor cells.

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.

Fractures in patients with hyperthyroidism and hypothyroidism: a nationwide follow-up study in 16,249 patients

AIM

To study fracture risk in patients with hyperthyroidism and hypothyroidism.

SUBJECTS AND METHODS

All patients with hyperthyroidism or autoimmune hypothyroidism diagnosed for the first time between 1983 and 1996 in Denmark were identified through the National Patient Discharge Register. Each patient was compared with three age- and gender-matched controls randomly selected from the general population. Fracture occurrence before and after diagnosis was compared between patients and controls.

RESULTS

11,776 patients with hyperthyroidism (6301 patients with diffuse toxic goiter, mean age, 52.1 +/- 18.6 years, and 5475 with nodular toxic goiter, mean age, 60.4 +/- 15.9 years), and 4473 patients with hypothyroidism (mean age, 66.1 +/- 17.3) were identified. In patients with hyperthyroidism, fracture risk was only significantly increased around the time of diagnosis (incidence rate ratio [IRR] between 1.26 and 2.29), but decreased to normal levels after diagnosis. Surgical treatment of hyperthyroidism was associated with a decreased fracture risk after diagnosis (RR = 0.66, 95% confidence interval [CI]: 0.55-0.78). In hypothyroidism, fracture risk was significantly increased both before and after diagnosis with a peak around the time of diagnosis (IRR between 2.17 and 2.35).

CONCLUSIONS

Fracture risk is increased in hyperthyroidism and hypothyroidism. Thyroid surgery seems associated with a decreased fracture risk in hyperthyroid patients.

Treatment of benign nodular goitre with mildly suppressive doses of L-thyroxine: effects on bone mineral density and on nodule size

OBJECTIVES

To evaluate (i) the demineralizing effect of L-thyroxine (LT4) therapy at doses mildly inhibiting serum thyroid stimulating hormone (TSH) in patients with benign nodular goitre; (ii) the efficacy of treatment on nodule size.

DESIGN

Cross-sectional study comparing euthyroid women with nodular goitre treated with LT4 for > or = 2 years (52 +/- 32 months, range 24-138, median 42) and a matched group with untreated goitre.

SUBJECTS

A total of 89 female outpatients (53.3 +/- 9 years; 36 pre- and 53 postmenopausal), 43 treated and 46 untreated.

MAIN OUTCOME MEASURES

Bone mineralization was measured with total body and regional mineralometry [dual energy X-ray absorptiometry (DEXA)], and indirectly evaluated with biochemical parameters (alkaline phosphatase, osteocalcin). Efficacy of LT4 therapy was assessed by measuring the nodule size during ultrasonography. The adequacy of the treatment was evaluated on the basis of serum TSH levels.

RESULTS

No significant differences were found at DEXA for total body and regional mineralization (P > 0.05 for all comparisons) in treated and untreated patients, both in pre- and postmenopausal states. Evaluation of the nodule size during the ultrasound scan showed a reduction of > or = 30% in 11 of 43 treated patients (26%) versus none of the untreated, an unchanged size in 29 treated patients (67%) versus 18 untreated, an increase of nodules and/or new nodule development in three treated patients (7%) versus 28 untreated (61%).

CONCLUSIONS

L-thyroxine (LT4) treatment at doses slightly suppressing TSH does not significantly affect bone mineralization, nor does it represent a risk factor for osteoporosis, even in postmenopausal patients. The efficacy of this therapeutic schedule on goitre size is comparable with the effects previously reported with suppressive doses.

Early changes in parameters of bone and mineral metabolism during therapy for hyper- and hypothyroidism

The effects of thyroid hormones on various organs and metabolic systems have been the focus of intensive research. In this study we investigated the mechanisms of the changes in some parameters of bone and mineral metabolism before and during treatment of hyper- and hypothyroidism. Our study groups were as follows; 1) Untreated hyperthyroid patients (n= 38), 2) Hyperthyroid patients treated for three months (n=21), 3) Untreated hypothyroid patients (n=27), 4) Hypothyroid patients treated for three months (n= 20), and 5) Euthyroid control subjects (age, weight, sex and menopausal status matched) (n = 47). As expected, the mean serum calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), and urinary Ca/creatinine and deoxypyridinoline (D-Pyr)/creatinine levels were higher in group-1 than in the control group. Serum PTH level was lower in group-1 than in group-5. However, after treatment for three months (group-2) we found that the serum and urinary levels of these parameters (except ALP) were not different than in the control group. Group-3 and group-4 did not show any differences in these parameters compared with group-5. Covariance analysis showed that urinary D-Pyr excretion had a positive, independent relationship to the serum free T3 level and age (P < 0.001 and P = 0.02, respectively). These results suggest that both bone formation and resorption markers increase in hyperthyroid patients, and with the treatment, particularly, in the period of first three months the bone resorption markers decrease rapidly. If the treatment is maintained the decrease slows, becoming more gradual. However, bone formation markers like ALP remain high in hyperthyroid patients during the treatment. In the light of this data, it is possible to conclude that osteoblastic activity lasts longer in hyperthyroidism. On the other hand, we demonstrated that these bone formation and resorption markers do not seem to be different in hypothyroid patients, even during the treatment, compared to the euthyroid controls.

Bone mass after long-term euthyroidism in former hyperthyroid women treated with (131)I influence of menopausal status

The objective of this study was to assess bone mineral density (BMD) and bone markers in former hyperthyroid females after long-term euthyroidism (>4 yr) following (131)I therapy, as well as the potential influence of the timing of menopause. Twenty-six females ages 57 +/- 8 yr previously diagnosed with hyperthyroidism and treated with (131)I who were euthyroid for a minimum of the last 4 yr (10 +/- 5 yr) were studied. Eighteen patients (69%) were on levothyroxine (LT(4)) replacement therapy for 9 +/- 4 yr. BMD (g/cm(2) and Z-score) was measured by dual X-ray absorptiometry in the lumbar spine, femoral neck, and Ward's triangle. BMD (Z-score) was lower than the normal reference values for the Spanish population in all sites (lumbar spine: -0.65 +/- 1.13; femoral neck: -0.47 +/- 0.95; Ward's triangle: -0.37 +/- 0.88). No differences were found between BMD values according to the etiology of the hyperthyroidism or current LT(4) therapy. Current postmenopausal patients (n = 21) showed lower BMD than current premenopausal patients in the lumbar spine and femoral neck (p < 0.05). Those women who were postmenopausal at the time of the (131)I therapy (n = 15) also had lower lumbar spine BMD than premenopausal patients (p = 0.01), while no significant difference in BMD was seen according to the menopausal status when hyperthyroidism was diagnosed. Former hyperthyroid patients after long-term euthyroidism following (131)I therapy showed reduced BMD at the lumbar spine and proximal femur. Menopausal women showed a greater reduction in bone density. The menopausal status at the time of diagnosis did not seem to have long-term effects in bone density; nevertheless, an early therapeutic intervention in premenopause is suggested to reduce bone loss.

Bone turnover in hyperthyroidism before and after thyrostatic management

Hyperthyroidism is associated with enhanced osteoblastic and osteoclastic activity, and patients frequently have low bone mineral density and high bone turnover. The aim of this study was to examine the bone formation and resorption markers trend in 12 female patients, before and after normalization of thyroid activity. The following measurements were made at baseline and 1 and 6 months after hormone normalization induced by methimazole treatment: total alkaline phosphatase (ALP), bone alkaline phosphatase (BALP), collagen type C-terminal propeptide (PICP), osteocalcin (BGP), telopeptide (ICTP), urinary-hydroxyproline/urinary creatinine (uOHP/uCreat), urinary calcium/urinary creatinine (uCa/uCreat) and deoxypyridinoline crosslinks (D-Pyr). Compared with controls, all of these parameters were significantly increased (ALP p = 0.014; BALP p = 0.0001; PICP p = 0.013; BGP p = 0.009; ICTP p = 0.0001; uOHP/uCreat p = 0.002; uCa/uCreat p = 0.044; crosslinks p = 0.0001). After treatment the values of ALP, BALP and PICP in hyperthyroid patients showed an initial slight increase and then a significant downwards trend (ALP p = 0.008, BAP p = 0.001, PICP p = 0.026). Furthermore, resorption markers showed a significant decrease (uOHP/ uCreat p < 0.005 and D-Pyr p < 0.008). As regards lumbar BMD patients, measurements were significantly reduced in comparison with the control group (p = 0.005). Six months after serum thyroid hormones level normalization, we observed a significant increase (p=0.014 vs baseline). Both neoformation and resorption markers are useful to assess pathological bone turnover and bone involvement in hyperthyroidism. They could also be employed to monitor the effect of antithyroid treatment on bone and to indicate if bone antiresorption therapy should be considered.

Reduced bone mineral density at diagnosis and bone mineral recovery during treatment in children with Graves' disease

OBJECTIVES

In children with Graves' disease, the prevalence of osteopenia is unknown, and the possible restoration of bone mass by antithyroid treatment has not been evaluated. The aim of this study was to prospectively evaluate the bone mineral density (BMD) and bone metabolism at diagnosis and after 1 and 2 years of medical treatment. Twenty-six children (19 girls and 7 boys) aged 11 +/- 3.4 years (range 3.4 to 15.3 years) were studied.

STUDY DESIGN

BMD of the lumbar spine and proximal femur were measured by dual-energy x-ray absorptiometry. Values were compared with those of healthy children of similar age, sex, and pubertal stage.

RESULTS

At diagnosis the mean BMD (standard deviation score [SDS]) was significantly reduced in both sites (P <.001) with a preferential loss of cortical bone (femoral BMD = -1.7 +/- 1.0 SDS) rather than trabecular bone (lumbar spine BMD = -0.8 +/- 1.1 SDS) (P =.003). Severe osteopenia (below -2 SDS) was found in 11 (42%) of 26 patients. Osteocalcin was significantly higher than in the control group (P <.0001), but other bone metabolism markers were normal. During treatment (n = 19) a significant gain in femoral (F = 14.7; P =.001) and lumbar spine (F = 5; P =.02) BMD (SDS) was observed, and none of the patients showed osteopenia. The annual percent change in the BMD values at the femoral (+23% +/- 11% and +6% +/- 4%, respectively, during the first and second years) and lumbar spine (+19% +/- 9% and +6% +/- 5%, respectively, during the first and second years) sites was greater during the first year than during the second year of treatment (P <.02 for femoral, P <.04 for lumbar spine). No significant age difference in BMD SD score or in BMD percent change values was observed. Osteocalcin returned rapidly to normal values, and all other bone metabolism markers remained in the normal range.

CONCLUSIONS

In conclusion, severe osteopenia was observed at diagnosis in children with Graves' disease but was rapidly corrected after 1 and 2 years of treatment. Initial reduced bone mass with high bone turnover caused by hyperthyroidism was corrected after 1 year of euthyroid conditions.

Vitamin D receptor initiation codon polymorphism in Japanese patients with Graves' disease

Recent studies have shown that related genetic influences on bone mineral density (BMD) and bone turnover are related to allelic variations in the vitamin D receptor (VDR) gene. Osteoporosis as a complication of hyperthyroidism is characterized by increased rates of both bone formation and bone resorption. In addition, VDR gene polymorphism influences susceptibility to some autoimmune diseases such as insulin-dependent diabetes mellitus (IDDM) and multiple sclerosis (MS). In the gene encoding the VDR, we investigated the distribution of a VDR-FokI polymorphism that changes the predicted protein sequence. The subjects were 131 female Japanese patients with Graves' disease and 150 female controls. The distribution of genotype frequencies differs between Graves' disease and controls (chi2 = 5.99, degrees of freedom = 2, p = 0.0386). We found overexpression of F allele (69% vs. 61%, p = 0.0472) and homozygote FF (48% vs. 33%, p = 0.0118) in Graves' disease patients compared with controls. We also correlated a VDR-FokI polymorphism with BMD in the distal radius and biochemical markers of bone turnover in patients with Graves' disease in remission. Although generally, no significant association was seen between age-adjusted BMD and genotype, patients in remission for fewer than 5 years showed significantly lower age-adjusted BMD in Ff heterozygotes than in ff homozygotes (z = 1.14 ff vs. z = -0.43 Ff, p < 0.05). Moreover, serum concentrations of bone alkaline phosphatase were significantly greater in Ff homozygotes than in FF homozygotes (78 +/- 12 vs. 59 +/- 10, p < 0.05). The genotypes did not differ in serum concentrations of osteocalcin, urinary hydroxyproline, or urinary deoxypyridinoline. Our results indicate, for the first time, an association between Graves' disease and a VDR polymorphism in the Japanese and suggest that a VDR-FokI polymorphism may affect bone mineral metabolism and can predict risk of osteoporosis as a complication of Graves' disease in patients in remission.

Variable bone mass recovery in hyperthyroid bone disease after radioiodine therapy in postmenopausal patients

OBJECTIVES

Long-term follow-up of postmenopausal hyperthyroid females after radioiodine therapy, since hyperthyroidism is known to cause impressive bone loss which may increase the risk of bone fractures.

METHODS

Bone mineral density (BMD) and biochemical parameters of bone metabolism in hyperthyroid postmenopausal patients were investigated before and 2 years after radioiodine therapy and compared with euthyroid age-matched controls.

RESULTS

At baseline, the incidence of low BMD with t-scores more than 2.5 S.D. below normal was significantly higher in hyperthyroid patients (54%) than in controls (20%, P<0.001). Regardless of initial BMD values, osteocalcin (OC) was also higher in all hyperthyroid patients (P<0.0001). After 2 years, all treated patients were euthyroid and OC levels were in the upper normal range. In hyperthyroid patients with initially low BMD, bone density values had increased significantly by +6.5% (P<0.008) as compared with baseline values. In contrast, hyperthyroid patients with initially normal BMD showed a further decrease in lumbar BMD values of -4.3% despite radioiodine treatment. BMD in euthyroid controls decreased by -6.5% within 2 years.

CONCLUSIONS

We conclude that hyperthyroid postmenopausal patients with generally increased bone turnover may show individual differences in bone loss and BMD recovery after radioiodine treatment. The mechanisms for this variable manifestation of osteoporosis have still to be elucidated, since this has implications for prophylactic and therapeutic strategies in these elderly patients.

Vitamin D receptor initiation codon polymorphism in Japanese patients with Graves' disease

Recent studies have shown that related genetic influences on bone mineral density (BMD) and bone turnover are related to allelic variations in the vitamin D receptor (VDR) gene. Osteoporosis as a complication of hyperthyroidism is characterized by increased rates of both bone formation and bone resorption. In addition, VDR gene polymorphism influences susceptibility to some autoimmune diseases such as insulin-dependent diabetes mellitus (IDDM) and multiple sclerosis (MS). In the gene encoding the VDR, we investigated the distribution of a VDR-FokI polymorphism that changes the predicted protein sequence. The subjects were 131 female Japanese patients with Graves' disease and 150 female controls. The distribution of genotype frequencies differs between Graves' disease and controls (chi2 = 5.99, degrees of freedom = 2, p = 0.0386). We found overexpression of F allele (69% vs. 61%, p = 0.0472) and homozygote FF (48% vs. 33%, p = 0.0118) in Graves' disease patients compared with controls. We also correlated a VDR-FokI polymorphism with BMD in the distal radius and biochemical markers of bone turnover in patients with Graves' disease in remission. Although generally no significant association was seen between age-adjusted BMD and genotype, patients in remission for >5 years showed significantly lower age-adjusted BMD in Ff heterozygotes than in ff homozygotes (Z = 1.14 ff vs. Z = -0.43 Ff, p < 0.05). Moreover, serum concentrations of bone alkaline phosphatase were significantly greater in Ff homozygotes than in FF homozygotes (78 +/- 12 vs. 59 +/- 10, p < 0.05). The genotypes did not differ in serum concentrations of osteocalcin, urinary hydroxyproline, or urinary deoxypyridinoline. Our results indicate, for the first time, an association between Graves' disease and a VDR polymorphism in the Japanese and suggest that a VDR-FokI polymorphism may affect bone mineral metabolism and can predict risk of osteoporosis as a complication of Graves' disease in patients in remission.

Bone mineral density and metabolism in children treated with L-thyroxine

It has been suggested that long term treatment with L-thyroxine could reduced bone mineral density (BMD). The purpose of this study was to determine whether BMD is decreased by L-thyroxine treatment in children. Dual energy X-ray absorptiometry (DEXA) was used to assess lumbar spine (L2-4) and femur neck BMD in 40 children aged 9-15 years, taking L-thyroxine (100 micrograms/m2/day) for a mean period of 1.45 +/- 0.60 years for colloid diffuse goiter. Patients were matched with controls for age, sex, weight, height and pubertal stage. BMD at both the femur neck and lumbar spine was not significantly different from that of the control group. No correlation was found between BMD values and TSH levels which is the index of tissue hyperthyroidism. BMD was also not correlated with duration of the therapy. Osteocalcin, alkaline phosphatase, calcitonin and parathormone levels were measured to asses bone turnover; none of them were significantly different from those of controls and they did not change during follow up. In conclusion we suggest that long-term L-thyroxine therapy in children has no adverse effect on BMD.

Effect of endogenous subclinical hyperthyroidism on bone metabolism and bone mineral density in premenopausal women

In this cross-sectional study, we evaluated 15 premenopausal women to elucidate whether bone turnover is increased and bone mineral density is reduced due to endogenous subclinical hyperthyroidism. Each patient had normal free thyroxine (FT4) and free triiodothyronine (FT3) levels associated with a stable suppression (<0.1 mU/L) of serum thyrotropin (TSH) levels during a period ranging between 6 and 11 months. Metabolic parameters of bone turnover (serum osteocalcin, bone specific alkaline phosphatase, procollagen I C-terminal peptide reflecting bone formation; urinary deoxypyridinoline and calcium excretion reflecting bone resorption) were assessed. Bone mineral density was measured at lumbar 1-4 vertebrae, femoral neck, and the forearm (midshaft radius and distal radius) by dual energy x-ray absorptiometry. All measurements were compared with 15 healthy age-, height-, and weight-matched premenopausal women who served as control group. Our findings suggest that endogenous subclinical hyperthyroidism is not associated with increased bone turnover, and bone mineral density is not reduced in premenopausal women, at least in the short term.

Bone turnover and cortical bone mineral density in the distal radius in patients with hyperthyroidism being treated with antithyroid drugs for various periods of time

OBJECTIVE

Whether patients, who have lost bone mass, can be restored to age-matched control levels by some means is still controversial. We investigated how the thyroid status after antithyroid drug therapy for various periods of time affects bone metabolism in patients with hyperthyroidism by assessing currently used biochemical markers of bone turnover and distal radius bone mineral density (BMD).

DESIGN AND PATIENTS

The biochemical markers of bone turnover and BMD at the distal one third of the radius were measured in 79 women with hyperthyroidism treated with antithyroid drugs for various periods of time. The patients were divided into two groups according to thyroid function at the time of study: a hyperthyroid group (serum thyroid stimulating hormone (TSH) < 0.4 mU/l) and an euthyroid group (TSH 0.4-4.0 mU/l). Second, each group was further divided according to the duration of therapy: short-term (less than 3 years) and long-term (3 or more years).

MEASUREMENTS

Urinary type I collagen degradation products (CTx) were measured by the CrossLapsTM ELISA kit. Urinary pyridinoline (Pyr) and deoxypyridinoline (Dpyr) were measured by high performance liquid chromatography (HPLC) after acid hydrolysis. Serum N-mid osteocalcin (OCN-mid) was measured by a recently developed enzyme-linked immunosorbent assay. Serum alkaline phosphatase (ALP) was determined by routine laboratory methods. Bone mineral density (BMD) at the distal one third of the radius was measured using dual energy X-ray absorptiometry (DEXA; DCS-600EX, Aloka, Tokyo).

RESULTS

There were statistically significant positive correlations of FT3 and FT4 with the biochemical markers of bone turnover. There were significant negative correlations between the biochemical markers and BMD only in patients undergoing long-term therapy. In a comparison between hyperthyroid and euthyroid groups based on duration of treatment (long-term and short-term), and in a comparison without regard for length of treatment (all patients), it was evident that ALP and CTx levels were significantly higher in the hyperthyroid than in the euthyroid groups. Significantly lower BMD Z-scores in the hyperthyroid group compared to those in the euthyroid group were observed only in patients undergoing long-term therapy.

CONCLUSIONS

Urinary type I collagen degradation products were a sensitive marker for evaluating the bone turnover in patients with hyperthyroidism. Our data suggested that it might be important to control the levels of TSH within normal ranges during long-term antithyroid drug therapy in order to prevent bone loss.

Secondary osteoporosis. Diagnostic considerations

This article discusses the important secondary causes of osteoporosis that contribute significantly to bone loss and that seem to increase fracture risk, including hypogonadism, endogenous and exogenous thyroxine excess, hyperparathyroidism, malignancies, gastrointestinal diseases, medications, vices, and connective tissue diseases.

Bone mineral density after surgical treatment for Graves' disease

Restoration of bone loss associated with thyrotoxicosis follows normalization of thyroid function. However, the extent of bone loss and restoration remain controversial. To clarify whether bone recovery is complete, we examined lumbar and femoral bone mineral density (BMD) by dual-energy x-ray absorptiometry (DXA) in 14 thyrotoxic premenopausal women with Graves' disease and 31 premenopausal women treated for Graves' disease by subtotal thyroidectomy who had been in remission for at least 3 years. In the remission group, to exclude the influence of subclinical hyperthyroidism, thyrotropin (TSH) levels were followed and subjects with low levels excluded. Thus, all 31 subjects had normal thyroid hormone levels with transiently or persistently elevated TSH levels post-thyroidectomy. Data from the two study groups were compared with those from healthy premenopausal controls matched for age, height and weight. Mean lumbar (anterior-posterior and lateral), femoral neck, and trochanter BMDs were significantly lower in the thyrotoxic group than in controls (p < .05, all four BMDs). Mean lumbar (anterior-posterior), femoral neck and trochanter BMDs were significantly higher in the remission group than in controls (p < 0.05, all three BMDs). At the time of DXA, the 31 remission subjects showed a significant positive correlation between lumbar BMD and TSH (p < 0.05) and a significant negative correlation between femoral neck BMD and free triiodothyronine (FT3) (p < 0.05). These observations suggest: (1) in premenopausal women, bone loss associated with thyrotoxicosis due to Graves' disease is present but is fully restored when remission is reached after subtotal thyroidectomy; (2) subclinical hypothyroidism after subtotal thyroidectomy may result in higher BMD than that of controls.

Fractures after thyroidectomy in men: a population-based cohort study

Bone mass is purportedly reduced by an endogenous or exogenous excess of thyroid hormone or, perhaps, by calcitonin deficiency. Patients who have undergone thyroidectomy could be subject to all of these effects, yet their practical implications in terms of fracture risk are poorly defined. Interpretation is further hampered by the focus on women, where results may be influenced by involutional osteoporosis. Consequently, we assessed the potential for fractures among the 136 Rochester, Minnesota men who underwent thyroidectomy between 1935 and 1979, relative to a group of age-matched control men from the community. With 2194 person-years of follow-up in each group, survival free of any fracture of vertebra, proximal humerus, distal forearm, pelvis, or proximal femur was similar in the two groups (p = 0.23), and the relative risk of any of these fractures for thyroidectomized patients versus their controls was increased only 1.5-fold (95% CI, 0.7-3.2). The difference was entirely accounted for by a statistically significant excess of proximal femur fractures in the men with thyroidectomy. Risk factors for fractures among men with thyroidectomy included greater age at surgery, greater extent of surgery, and the presence of risk factors for secondary osteoporosis. Thus, thyroidectomy, performed mainly for adenoma or goiter, seems to have little overall influence on the risk of age-related fractures in men. However, the association with hip fractures requires further evaluation.

Antiresorptive therapy in hyperthyroid patients: longitudinal changes in bone and mineral metabolism

The effect of antiresorptive therapy with nasal calcitonin (CT) in recently diagnosed hyperthyroid patients on conventional medical therapy as well as the evolution of bone metabolism were assessed. Forty-five patients with recent-onset hyperthyroidism (<12 weeks) were sex and menopause stratified and randomly allocated to treatment with carbimazole (Neotomizol), carbimazole plus low dose CT (Calsynar; 100 IU/day, 2 days/week), or carbimazole plus high dose CT (Calsynar; 100 IU/day, 14 days/month). Bone mineral density was measured by dual x-ray absorptiometry in lumbar spine, femoral neck, and Ward's triangle at 0, 9, and 18 months of treatment. We also determined free T4, free T3, TSH, osteocalcin, total and bone alkaline phosphatases, tartrate-resistant acid phosphatase, type I collagen C telopeptide, and urinary hydroxyproline every 3 months of follow-up. No significant difference was observed among treatments. A euthyroid state was attained at 3 months. Bone mass increased significantly at the 9 month evaluation (P < 0.05), with a 5-10% net gain during follow-up. Nevertheless, final bone mass was 4-8% smaller than expected. Bone formation markers were increased at 0 and 3 months, with reductions at 6-9 months; resorption bone markers showed a significant reduction at the 3 month evaluation. These results indicate that the euthyroid state partially reduces hyperthyroidism-associated osteopenia, with a bone mass recovery period during the 6-9 early months of effective treatment. This recovery phase is characterized by raised bone formation markers and reduced bone resorption markers. The treatment with nasal CT at the doses assayed has no additional effect over that of attainment of the euthyroid state.

A longitudinal study of markers of bone turnover in Graves' disease and their value in predicting bone mineral density

Whether biochemical markers can predict improvement in reduced bone mineral density (BMD) associated with thyrotoxicosis in unclear. We investigated the relationship between serum osteocalcin (OC), bone-specific alkaline phosphatase (b-ALP), serum deoxypyridinoline (Sdpd) and pyridinoline (Spyr), 24-hour urinary deoxypyridinoline (Udpd), and BMD in 17 thyrotoxic patients during 1 yr of treatment. Coinciding with euthyroidism at 4-8 weeks, there was a peak in b-ALP and OC and a prompt fall into the normal range in Udpd and Sdpd, but not Spyr, levels. Mean b-ALP continued to be raised at week 52 when it was inversely correlated with BMD. Mean BMD rose approximately 6%, P < 0.01, over 1 yr. Coupling indices were calculated as a measure of bone balance and, at diagnosis, was [minus4.26 in favor of bone resorption and rose with treatment in favor of bone formation: weeks 2: -0.23; 4: +4.01; 8: +4.37; 12: +4.44; 24: +2.32; and 52: +1.56. Bone turnover is balanced within 2 weeks of starting treatment for thyrotoxicosis. Udpd accurately indicates thyrotoxic bone resorption. Serum b-ALP indicates continuing bone formation and, at 1 yr, may provide a marker for low BMD. OC, Sdpd, and Spyr are less sensitive in documenting bone remodeling during treatment of thyrotoxicosis.

Skeletal integrity in men chronically treated with suppressive doses of L-thyroxine

We measured bone mineral density (BMD) (lumbar spine, femoral neck, Ward's triangle, and trochanter) in 34 men given suppressive doses of levothyroxine (L-T4) for a mean of 10.2 years. Indications for treatment were nontoxic goiter (n = 5) or thyroidectomy for differentiated thyroid cancer (n = 6) or nontoxic goiter (n = 3). Patients were followed at our institution and treated with the minimal amount of L-T4 able to suppress thyroid-stimulating hormone (TSH). At the time of evaluation, free T3 was normal in all cases, whereas free T4 was increased in 14 men (41.2%). The mean daily dose of L-T4 was 172 +/- 6 microg, and the cumulative dose of L-T4 was 673 +/- 71 mg. We found no significant difference between patients and age- and weight-matched controls in BMD (g/cm2) at any site of measurement (lumbar spine 1.144 +/- 0.12 vs. 1.168 +/- 0.15; femoral neck 0.979 +/- 0.13 vs. 1.001 +/- 0.13; Ward's triangle 0.854 +/- 0.17 vs. 0.887 +/- 0.15; and trocanther 0.852 +/- 0.13 vs. 0.861 +/- 0.13). BMD was not correlated with the duration of therapy, cumulative or mean daily dose of L-T4, serum levels of free T4, free T3, osteocalcin, and bone alkaline phosphatase. Serum calcium and osteocalcin were slightly but significantly elevated in patients compared with controls, whereas there was no difference in intact parathyroid hormone, bone alkaline phosphatase, and sex hormone-binding globulin (marker of thyroid hormone action). Our data suggest that L-T4 suppressive therapy, if carefully carried out and monitored, using the smallest dose necessary to suppress TSH secretion, has no significant effects on bone metabolism and bone mass in men.

Is skeletal responsiveness to thyroid hormone altered in primary osteoporosis or following estrogen replacement therapy?

Hyperthyroidism is characterized by increased bone turnover and resorptive activity. Similar changes in remodeling are seen in osteoporosis. To study the pathogenetic role of thyroid hormone in osteoporosis, we measured concentrations of free and total thyroid hormones and investigated the sensitivity of the skeleton toward thyroid hormones in 14 osteoporotic, 16 estrogen-treated, and 15 normal postmenopausal women with comparable thyroid status. Triiodothyronine (T3, 60 microg/day for 7 days) was administered to the three groups. The skeletal response was assessed by monitoring bone alkaline phosphatase (BAP), osteocalcin (BGP), and pyridinium cross-linked telopeptide domain of type I collagen (ICTP) in serum and urinary excretion of hydroxyproline (OHP), pyridinoline (PYR), and deoxypyridinoline (DPR) at days 0, 8, 15, and 57. Women on estrogen replacement therapy exhibited lower bone turnover than the normal postmenopausal women. Markers of bone formation were reduced by 19-43% and markers of resorption by 22-48%. The osteoporotic women displayed lower bone mass at the lumbar spine and the distal forearm (p < 0.01-0.001), but the levels of biochemical markers of bone formation and resorption were comparable to values obtained in the normal postmenopausal women. T3 stimulation caused significant increases (p values ranging between 0.05-0.001) in all three groups of the resorptive markers: ICTP (47%, 47%, 45%), OHP (29%, 30%, 33%), PYR (43%, 27%, 51%), and DPR (42%, 24%, 59%). Of the formative markers, only BGP increased significantly (32%, 40%, 47%) (p < 0.001). At day 57, however, all three formative markers increased compared with day 15 (p < 0.05-0.001). No significant differences in bone markers were demonstrated between groups. In the osteoporotic group, as the only group, serum calcium increased (p < 0.05) and serum PTH fell (p < 0.05). In conclusion, osteoporosis and estrogen substitution are not characterized by altered concentrations of thyroid hormones or responsiveness to thyroid hormones at the level of individual bone cells; however, altered responses pertaining to PTH and calcium were detected.

Spontaneous release of interleukin 1 beta from human blood monocytes in thyrotoxic osteodystrophy

Hyperthyroidism is a well documented cause of impaired bone turnover characterized by increased osteoblastic and osteoclastic activity, resulting in predominance of bone resorption and in decreased bone mass. Thyroid hormones can carry out a direct effect on osteoblasts which express specific receptors on their surface membrane; differently effect on osteoclast seems to be mediated by local factors, cytokynes released by activated osteoblasts or by bone monocytes cells. Interleukin 1 beta is the first purified cytokyne shown to have bone resorbing activity. In ten thyrotoxic female patients IL 1 beta in the cellular medium of the monocytes blood cells culture has been measured, compared to PYD/cr urinary excretion, and FT3, BGP serum levels, before and after thyrostatic treatment. Ten normal females were studied as control group. The results before treatment showed osteopenia in 20% (DEXA densitometry), increased values of FT3, BGP, IL 1 beta and PYD/cr in patients versus controls (p < 0.001). The thyrostatic therapy obtained normalization of IL 1 beta, PYD/cr, BGP, and FT3 levels. Our data demonstrate that increased thyroid hormone levels in vivo are associated to increased secretion of monocytes cytokynes in vitro and suggest that alterations in local production of bone acting cytokyne may underlie to thyrotoxic osteodistrophy.

Serum concentrations of osteocalcin in pregnant women with multinodular thyroid goiter undergoing treatment with levothyroxine

In this study we measured serum osteocalcin (Bone Gla-Protein) to investigate bone metabolism in pregnant women with multinodular thyroid goiter undergoing treatment with levothyroxine (L-T4). Serum concentration of BGP was measured in 18 pregnant women and in 20 non-pregnant women (ages raging from 21-34 years) receiving L-T4 (75-125 micrograms/day). Venous blood samples for RIA determination of serum BGP, plasma thyroid hormone (T3, T4, free T3, free T4) and TSH were collected from the two groups. The samples of the pregnant women group were collected before pregnancy (at the moment the disease was diagnosed without L-T4 therapy) during pregnancy (at the 3rd, 6th and 9th month) and one month after delivery. The normal TSH levels (measured with Irma method) before pregnancy, were significantly reduced during treatment with L-T4 during pregnancy and after delivery (p < 0.005), respectively. Also in the control group TSH levels were reduced during treatment. Serial measurement of serum BGP before pregnancy, (3.4 +/- 1 ng/ml) during pregnancy (3rd: 4.2 +/- 1.5 ng/ml; 6th: 4.2 +/- 1.4 ng/ml; 9th: 2.8 +/- 1.6 ng ml, month respectively) and one month after delivery (3.5 +/- 1.3 ng/ml) did not demonstrate significant variations. Furthermore, in the control group the BGP levels were 3.2 +/- 1.7 ng/ml. There was no correlation between BGP, thyroid hormones and TSH in these groups. These data indicate that the administration of moderate doses of L-T4 in pregnant and in non-pregnant women did not modify the serum BGP levels.