Peripheral bone density in women with untreated multinodular goitre

Body iodine status in women with postmenopausal osteoporosis

OBJECTIVE

Postmenopausal osteoporosis is a frequent cause of morbidity and can negatively impact life expectancy; iodine is an essential element for bone mineralization, and iodine deficiency is frequently observed. The aim of the present study was to understand the connection between postmenopausal osteoporosis and the level of iodine in the body.

METHODS

A total of 132 participants were divided into three groups: group 1 consisted of healthy postmenopausal women (n = 34), group 2 comprised osteopenic women (n = 38), and group 3 included women with postmenopausal osteoporosis (n = 60). The three groups were compared according to demographic, clinical, and laboratory findings.

RESULTS

The urinary iodine levels were recorded as 216.1 ± 125.2 in the control group, 154.6 ± 76.6 in the osteopenic group, and 137.5 ± 64.9 in the postmenopausal osteoporosis group (P < 0.001). These differences were maintained after adjustment for body mass index (P < 0.001). The urinary iodine level accurately correlated with the total T-score for the lumbar spine (r = 0.236, P = 0.008). Multiple regression analysis showed that corrected for body mass index, alkaline phosphatase isoenzyme, and urinary deoxypyridinoline, the urinary iodine level was significantly associated with total T-score (beta coefficient = 0.270, P = 0.006).

CONCLUSIONS

The urinary iodine level was significantly lower in women with postmenopausal osteoporosis, and iodine replacement may be important in preventing osteoporosis in areas where iodine deficiency is endemic.

Symptoms of thyrotoxicosis, bone metabolism and occult atrial fibrillation in older women with mild endogenous subclinical hyperthyroidism

OBJECTIVE

The objective of this study was to evaluate symptoms of thyrotoxicosis, bone turnover, bone mineral density (BMD) and occult atrial fibrillation (AF) in women ≥65 years with mild endogenous subclinical hyperthyroidism (SCH).

DESIGN

Cross-sectional and case-control study.

PATIENTS

Signs and symptoms of thyrotoxicosis, serum carboxyterminal telopeptide (CTx) and procollagen type I N-terminal propeptide (PINP), BMD, resting electrocardiogram (ECG) and 72-h ECG monitoring were evaluated in 180 women ≥65 years, including 90 with mild SCH (TSH between 0·1 and 0·4 mIU/l) and 90 euthyroid controls matched for age and body mass index.

RESULTS

Symptom Rating Scale scores did not differ between patients and controls. None of the patients with SCH scored 20 points, a score compatible with clinical thyrotoxicosis. Eighty patients with SCH (89%) obtained seven or fewer points, a score compatible with euthyroidism. No difference in serum CTx or PINP concentrations was observed between patients and controls. There was also no correlation between these markers and TSH, free T4 or total T3 levels. Finally, no difference in femoral neck or lumbar spine BMD was observed between patients with SCH and controls. Three patients with SCH (3·3%) and two euthyroid women (2·2%) had known AF or AF in the resting ECG. ECG monitoring for 72 h revealed episodes of occult AF in 1/87 patients with SCH and in 1/88 euthyroid women (1·1%).

CONCLUSIONS

Mild endogenous SCH (TSH between 0·1 and 0·4 mIU/l) was not associated with symptoms of thyrotoxicosis, altered bone metabolism or a higher prevalence of occult AF in women ≥65 years.

Bone mineral density in geriatric patients with toxic nodular goiter

BACKGROUND AND AIMS

We aimed to assess bone mineral density (BMD) in geriatric patients with hyperthyroidism caused by TNG.

MATERIALS AND METHODS

Bone mineral density was measured at the lumbar spine and proximal femur, using dual-X-ray absorptiometry (DXA) in 90 patients with TNG (mean age; 69.2 ± 4.4 years) and compared with those in 42 age-matched healthy subjects (mean age; 68.40 ± 4.3 years). Serum levels of TSH, fT3, fT4, 25-OH vitamin D and PTH were measured.

RESULTS

BMD was significantly lower at total spine (0.904 ± 0.1 vs. 1.114 ± 0.1 g/cm(2)) and total hip (0.850 ± 0.1 vs. 1.079 ± 0.1 g/cm(2)) in male patients with TNG in comparison to the healthy men (p = 0.001, p < 0.001). Postmenopausal women with TNG had lower BMD measurements at total lumbar spine (0.754 ± 0.1 vs. 0.870 ± 0.2 g/cm(2), p < 0.001) and total hip (0.765 ± 0.1 vs. 0.831 ± 0.2 g/cm(2), p < 0.001) in comparison to the healthy women. T scores of total lumbar spine and hip were lower in patients with subclinical hyperthyroidism compared to the control group, respectively (-1.9 ± 1.7 vs -0.8 ± 1.8, p = 0.007; -1.09 ± 1.2 vs. -0.02 ± 1.6, p = 0.001). While serum levels of fT3 and fT4 revealed a negative correlation with T score of BMD measurements at the total spine and hip, TSH levels were positively correlated. We did not find a difference in serum calcium, phosphorus, 25-OH vitamin D and PTH levels between the two groups (p > 0.005).

CONCLUSION

Geriatric patients with hyperthyroidism secondary to TNG had reduced BMD at the total spine and hip. Thus, we suggest to investigate bone mineral density in geriatric patients with TNG.

Prevalence of silent vertebral fractures detected by vertebral fracture assessment in young Portuguese men with hyperthyroidism

BACKGROUND

Hyperthyroidism is a risk factor for reduced bone mineral density (BMD) and osteoporotic fractures. Vertebral fracture assessment (VFA) by dual-energy X-ray absorptiometry (DXA) is a radiological method of visualization of the spine, which enables patient comfort and reduced radiation exposure.

OBJECTIVES

This study was carried out to evaluate BMD and the prevalence of silent vertebral fractures in young men with hyperthyroidism.

DESIGN

We conducted a cross-sectional study in a group of Portuguese men aged up to 50 years and matched in hyperthyroidism (n=24) and control (n=24) groups.

MATERIALS AND METHODS

A group of 48 Portuguese men aged up to 50 years was divided and matched in hyperthyroidism (n=24) and control (n=24) groups. BMD (g/cm(2)) at L1-L4, hip, radius 33%, and whole body as well as the total body masses (kg) were studied by DXA. VFA was used to detect fractures and those were classified by Genant's semiquantitative method. No patient had previously been treated for hyperthyroidism, osteoporosis, or low bone mass. Adequate statistical tests were used.

RESULTS

The mean age, height, and total fat mass were similar in both groups (P≥0.05). The total lean body mass and the mean BMD at lumbar spine, hip, and whole body were significantly decreased in the hyperthyroidism group. In this group, there was also a trend for an increased prevalence of reduced BMD/osteoporosis and osteoporotic vertebral fractures.

CONCLUSIONS

The results obtained using VFA technology (confirmed by X-ray) suggest that the BMD changes in young men with nontreated hyperthyroidism may lead to the development of osteoporosis and vertebral fractures. This supports the pertinence of using VFA in the routine of osteoporosis assessment to detect silent fractures precociously and consider early treatment.

Should we treat mild subclinical/mild hyperthyroidism? Yes

Whether or not subclinical hyperthyroidism (SCH) should be treated, remains a matter of debate because there are no randomized clinical trials answering the question if treatment improves long-term health outcomes. Cross-sectional and longitudinal population-based sudies demonstrate clear associations between SCH and risk on atrial fibrillation and fractures; associations with cardiovascular and overall mortality and mental health are less consistent. Associations with adverse outcomes of cardiovascular and bone health are in all likelihood causally related to SCH in view of an observed dose-response relationship and the existence of a plausible biologic mechanism. Short-term intervention studies show improvement of surrogate outcome measurements. Against this background treatment of both endogenous and exogenous SCH is recommended when TSH is 0.1 mU/l or lower. At TSH values>0.1-<0.4 mU/l treatment should be considered in the presence of risk factors (age>65 years, post menopause, osteoporosis, cardiac disease).

Modeling the effect of levothyroxine therapy on bone mass density in postmenopausal women: a different approach leads to new inference

BACKGROUND

The diagnosis, treatment and prevention of osteoporosis is a national health emergency. Osteoporosis quietly progresses without symptoms until late stage complications occur. Older patients are more commonly at risk of fractures due to osteoporosis. The fracture risk increases when suppressive doses of levothyroxine are administered especially in postmenopausal women. The question is; "When should bone mass density be tested in postmenopausal women after the initiation of suppressive levothyroxine therapy?". Standard guidelines for the prevention of osteoporosis suggest that follow-up be done in 1 to 2 years. We were interested in predicting the level of bone mass density in postmenopausal women after the initiation of suppressive levothyroxine therapy with a novel approach.

METHODS

The study used data from the literature on the influence of exogenous thyroid hormones on bone mass density. Four cubic polynomial equations were obtained by curve fitting for Ward's triangle, trochanter, spine and femoral neck. The behaviors of the models were investigated by statistical and mathematical analyses.

RESULTS

There are four points of inflexion on the graphs of the first derivatives of the equations with respect to time at about 6, 5, 7 and 5 months. In other words, there is a maximum speed of bone loss around the 6th month after the start of suppressive L-thyroxine therapy in post-menopausal women.

CONCLUSION

It seems reasonable to check bone mass density at the 6th month of therapy. More research is needed to explain the cause and to confirm the clinical application of this phenomenon for osteoporosis, but such an approach can be used as a guide to future experimentation. The investigation of change over time may lead to more sophisticated decision making in a wide variety of clinical problems.

Approach to the patient with subclinical hyperthyroidism

Endogenous subclinical hyperthyroidism, defined by normal circulating levels of free T4 and T3 and low levels of TSH, is a common clinical entity and is typically caused by the same conditions that account for the majority of cases of overt hyperthyroidism: Graves' disease, toxic multinodular goiter, and solitary autonomously functioning thyroid nodules. Subclinical hyperthyroidism has been associated with an increased risk of atrial fibrillation and mortality, decreased bone mineral density in postmenopausal women, and mild hyperthyroid symptoms. Treatment of subclinical hyperthyroidism remains controversial, given the lack of prospective randomized controlled trials showing clinical benefit with restoration of the euthyroid state. Nevertheless, it seems reasonable to treat older individuals whose serum TSH levels are less than 0.1 mU/liter and certain high-risk patients, even when the serum TSH is between 0.1 and the lower limit of the normal range.

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.

Low normal TSH levels are associated with low bone mineral density in healthy postmenopausal women

OBJECTIVE

Hyperthyroidism is accompanied by low bone mass. Because the reference range of TSH levels is defined statistically, some individuals with low normal TSH levels may have mild hyperthyroidism and reduced bone mass. We therefore determined whether serum TSH levels correlate with bone mineral density (BMD).

DESIGN

A cross-sectional hospital-based survey. Participants Nine hundred and fifty-nine healthy postmenopausal women.

MEASUREMENTS

We measured BMD at the lumbar spine and femoral neck using dual energy X-ray absorptiometry, and serum TSH concentrations using immunoluminometry.

RESULTS

BMD at the lumbar spine and femoral neck increased with TSH level (P for trend < 0.001 at both sites). Even after adjustment for age, years since menopause and body mass index, subjects with low normal TSH levels (0.5-1.1 mU/l) had significantly lower BMDs at the lumbar spine (0.863 +/- 0.009 g/cm2 vs 0.900 +/- 0.009 g/cm2, P = 0.004) and femoral neck (0.660 +/- 0.006 g/cm2 vs 0.683 +/- 0.006 g/cm2, P = 0.006) than those with high normal TSH levels (2.8-5.0 mU/l), as well as a 2.2-fold increased risk of osteoporosis (95% confidence interval: 1.2-4.0).

CONCLUSION

These results suggest that low normal TSH levels may not be physiological for postmenopausal women and, during treatment of hypothyroidism, may not be adequate for avoiding osteoporosis.

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.

Hip bone mineral density, bone turnover and risk of fracture in patients on long-term suppressive L-thyroxine therapy for differentiated thyroid carcinoma

OBJECTIVE

Untreated hyperthyroidism and treatment with high doses of thyroid hormone are associated with osteoporosis. However, their effect on bone turnover, their contribution to bone mineral density (BMD) in the context of other clinical risk factors for osteoporosis and the prevalence of vertebral fractures is not well documented.

DESIGN

Cross-sectional study.

METHODS

We studied 59 patients receiving L-thyroxine suppressive therapy for differentiated thyroid carcinoma (DTC). BMD of the hip was measured by dual X-ray absorptiometry (DXA) and lateral DXA pictures of the lumbar and thoracic vertebrae were performed. Bone resorption was measured by C-telopeptides of type I collagen (ICTP) and bone formation by procollagen type I N-propeptide (PINP). Clinical risk factors for osteoporosis were evaluated using a questionnaire.

RESULTS

Z-scores of BMD were similar as the NHANES (National Health and Nutrition Examination Survey) III reference group in women and men, also after long-term (> 10 years) suppression therapy. Patients in the lowest and highest quartile of BMD showed significant differences in the presence of clinical risk factors. ICTP levels were significantly higher than in age-matched controls, PINP levels were not different. We found four patients with a prevalent vertebral fracture.

CONCLUSIONS

We conclude that patients with well-differentiated thyroid carcinoma are not at increased risk of developing low bone mass nor have a higher prevalence of vertebral fracture at least when treated with relatively low doses of L-thyroxine.

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.

Subclinical hyperthyroidism: to treat or not to treat?

Subclinical hyperthyroidism may be defined as the presence of free thyroxine and tri-iodothyronine levels within the reference range and a reduced serum thyroid stimulating hormone (TSH) level. In this review the prevalence of low TSH in the population and health consequences of subclinical hyperthyroidism, for example, effects on heart and bone mass, are discussed. Guidelines for treatment are given, based on expert opinion.

Disfunções mínimas da tiróide: hipotiroidismo subclínico e hipertiroidismo subclínico

Hipotiroidismo subclínico (SHT) e hipertiroidismo subclínico (SCH) são definidos pelas concentrações normais de T4 e T3 livres séricos associadas com valores de TSH elevado (SHT) ou suprimido (SCH). As prevalências são baixas e sintomas e sinais de disfunção tiroideana escassos. No SHT, colesterol total e LDL-C estão ligeiramente elevados, e tratamento com levotiroxina pode influir nos valores dos lipídeos. Ocorre diminuição da contratilidade do miocárdio e aumento da resistência vascular periférica, que melhoram com o tratamento. Fibrilação atrial é mais freqüente no SCH, e há aumento do índice de massa do ventrículo esquerdo, da contratilidade cardíaca, disfunção diastólica e indução de batimentos atriais ectópicos que regridem com uso de beta-bloqueadores. No SCH, ocorre diminuição da densidade óssea. Depressão, doença do pânico e alterações de testes cognitivos são freqüentes no SHT. O tratamento do SHT é indicado com TSH sérico maior do que 8mU/L e presença de anticorpos antitiroideanos, e do SCH endógeno, quando existem sintomas, em idosos ou concentração de TSH menor do que 0,1mU/L.

The management of subclinical hyperthyroidism by thyroid specialists

Subclinical hyperthyroidism is a relatively common condition for which prospectively derived evidenced-based management guidelines do not exist. We have conducted a case-based mail survey to solicit opinions from members of the American Thyroid Association (ATA) about various issues that arise in the management of patients with this disorder. The survey was completed and returned by 185 of 300 (62%) of the original survey recipients. Four hypothetical cases varying in age, thyrotropin (TSH) level and underlying etiology were presented. The majority of respondents recommended further evaluation of all cases, most commonly choosing a radioactive iodine uptake (42%-71%), thyroid scan (39%-68%) and antithyroid (TPO/Tg) antibodies (49%-55%) as the additional tests to be ordered. The large majority (84%) recommended observation rather than active treatment for a young patient with a low but detectable serum TSH level. A small majority also recommended observation alone for a young woman with an undetectable serum TSH level (58%) and for an older woman with a low but detectable serum TSH value (63%). However, the majority (66%) favored treating an older woman with an undetectable serum TSH. When treatment was advised in the patients with subclinical hyperthyroidism, the respondents strongly favored anti-thyroid drugs when the etiology was Graves' disease and radioactive iodine when the etiology was toxic nodular thyroid disease. In the absence of adequate evidence-based guidelines, it is hoped that this survey of expert opinions may provide useful guidance for physicians providing care for patients with subclinical hyperthyroidism.

Screening for thyroid disorders in asymptomatic adults from Brazilian populations

Advances in thyroid disorder diagnosis have created new thyroid disorder categories such as subclinical hyperthyroidism and subclinical hypothyroidism. In the 1980s, immunometric assaying for thyroid stimulating hormone (TSH) emerged and became defined as the most cost-effective test in thyroid disorder screening. The second step in the screening of thyroid disorders is to determine free thyroxine (FT4), and cost-effective methods for its detection are now available. Using TSH and FT4, it is possible to determine four situations: clinical hyperthyroidism, clinical hypothyroidism, subclinical hyperthyroidism and subclinical hypothyroidism. Subclinical hypothyroidism can be a strong indicator of risk for atherosclerosis and myocardial infarction in elderly women. Cardiovascular mortality among Brazilian women is one of the highest in the Western world. The best-known risk factors for cardiovascular diseases are high blood pressure, smoking, diabetes, and hypercholesterolemia. Although these are recognized as primary risk factors, there are other risk factors that could be identified as primordial risk factors. This may be the case for subclinical hypothyroidism. Early detection of thyroid disorders in women over fifty could be a highly cost-effective option in the prevention of cardiovascular disorders among Brazilian women.

Serum thyroid-stimulating hormone measurement for assessment of thyroid function and disease

Third generation thyroid stimulating hormone (TSH) assays have emerged as the single most useful test of thyroid function, and are used widely and appropriately as a screening test. TSH measurement alone may be misleading in complicated patients and those undergoing treatment for thyroid dysfunction. Before obtaining thyroid function tests, clinicians need to consider whether the patient might have pituitary or hypothalamic disease or severe nonthyroidal illness, and whether assessment of the pituitary-thyroid axis reflects steady-state conditions. Subclinical hyperthyroidism is associated with adverse effects on the skeleton and the heart, and is best assessed by measurement of serum TsH with a third-generation assay.

The utility of thyroid nuclear imaging and other studies in the detection and treatment of underlying thyroid abnormalities in patients with endogenous subclinical thyrotoxicosis

PURPOSE

Endogenous subclinical thyrotoxicosis is diagnosed when a patient who is not taking exogenous thyroid hormone has a suppressed level of thyroid-stimulating hormone with normal levels of the free thyroid hormones thyroxine and triiodothyronine and other known causes of a suppressed thyroid-stimulating hormone level have been excluded. Although such a condition is caused by underlying thyroid disease, the specific nature and relative prevalence of these disorders and the utility of nuclear imaging and other studies in their detection remains unclear.

PATIENTS AND METHODS

The authors performed a retrospective study of 50 patients with endogenous subclinical thyrotoxicosis. The results of the history and physical examination, thyroid nuclear scan, radioactive iodine uptake measurement, and thyroid antibody studies were reviewed. The results of the nuclear imaging and thyroid antibody studies were combined in an attempt to establish an underlying diagnosis for each patient.

RESULTS

The thyroid nuclear imaging and antibody studies were used to establish a specific thyroid disorder in most of the patients (n = 39). These disorders included most commonly toxic multinodular goiter, various forms of autoimmune thyroid disease, and solitary toxic adenoma. A specific diagnosis was not determined in 11 patients. Therapy with I-131 radioactive iodine was administered to 14 of these patients, 13 of whom subsequently achieved a normal thyroid-stimulating hormone level.

CONCLUSIONS

Most patients with endogenous subclinical thyrotoxicosis have underlying thyroid abnormalities that can be determined by nuclear imaging and, in selected cases, thyroid antibody studies.

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 mineral density in premenopausal women receiving levothyroxine suppressive therapy

Osteoporosis is a well-known complication of thyrotoxicosis. Prolonged subclinical hyperthyroidism due to L-thyroxine treatment has been associated with reduced bone mass and thus with the potential risk of premature development of osteoporosis. The aim of this study was to assess the effect of a chronic L-thyroxine suppressive treatment on bone mineral density (BMD) in a group of premenopausal women. Forty consecutive patients (mean age +/- SE = 40.95 +/- 1.56 years) affected by non-toxic goiter underwent bone mineral densitometry (dual energy X-ray absorptiometry; DEXA) of the lumbar spine (L1-L4) and right femoral neck. At the time of the study the patients had been under thyroid stimulating hormone (TSH) suppressive therapy for 74.95 +/- 10.34 months (range 17-168 months). Baseline levels of free thyroxine (fT4), free triiodothyronine (fT3), TSH, calcium and phosphorus were measured and correlated with BMD. The age of starting, duration of treatment, main daily dose, cumulative dose of treatment and body mass index (BMI) were also correlated with BMD. Statistical analysis was performed by multiple linear regression. BMD among female patients was not significantly different from that of the general population matched for age and sex. With the use of the regression model, no significant correlation was found between BMD and the variables considered. In conclusion, our data suggest that L-thyroxine suppressive therapy, if carefully carried out and monitored, has no significant effect on bone mass.

Subclinical thyroid disease in the elderly

The development of sensitive assays for thyrotropin (TSH) has led to the discovery that many older patients have abnormal TSH levels without other alterations in serum thyroid hormone levels, conditions termed subclinical hypothyroidism (isolated elevation of TSH levels) and subclinical hyperthyroidism (isolated suppression of TSH levels). Subclinical hypothyroidism occurs in 5% to 10% of elderly subjects, and is especially prevalent in elderly women. Subclinical hyperthyroidism is less common, affecting less than 2% of the elderly population. The causes of subclinical thyroid disease in the elderly are similar to those of thyroid disease in the general population, although medications and iodine-containing compounds may play an increased role. Potential risks of subclinical hypothyroidism in the elderly include progression to overt hypothyroidism, cardiovascular effects, hyperlipidemia, and neurological and neuropsychiatric effects. Potential risks of subclinical hyperthyroidism in the elderly include progression to overt hyperthyroidism, cardiovascular effects (especially atrial fibrillation), and osteoporosis. Decisions to treat elderly subjects with subclinical thyroid disease should be based on a careful assessment of these risks in the individual patient.

Normalization of serum thyrotrophin by means of radioiodine treatment in subclinical hyperthyroidism: effect on bone loss in postmenopausal women

BACKGROUND

Patients with subclinical hyperthyroidism (reduced serum TSH and normal free T4 and T3 concentrations) have slightly increased bone turnover and might have reduced bone mass, especially among postmenopausal women (due to concomitantly reduced oestrogen production), as also seen during suppressive L-T4 treatment.

OBJECTIVE

We have evaluated whether normalization of serum TSH using radioiodine treatment (RAI) in postmenopausal women with a nodular goitre and subclinical hyperthyroidism, protects against bone loss?

DESIGN

Prospective, non-randomized study, outpatients 2 years follow-up.

PATIENTS

Postmenopausal women with a nodular goitre, biochemically subclinical hyperthyroidism (TSH < 0.2 mU/I, and signs of a growing goitre or compression symptoms. Sixteen were treated with RAI (median dose 555 MBq) (+RAI), whereas 12 were followed without treatment (-RAI).

MEASUREMENTS

Serum TSH (third generation technology), free T4 and T3 indices, and bone mass (BMD) as measured by Dual Photon Absorptiometry (4 in each group) (only spine) or Dual X-ray Absorptiometry (DEXA) (both spine and hip), were measured yearly for up to 2 years.

RESULTS

The two groups did not differ regarding age, thyroid hormone parameters, and absolute levels of BMD at spine and hip. RAI resulted in normalization of TSH in all 16 women, and FT4I as well as FT3I decreased to 78% after one year (P < 0.01). These parameters did not change in the untreated group, thus serum TSH remained reduced. BMD at the spine tended to increase (n.s.) after RAI to (median) 101.9% after one year, and 101.5% after 2 years. In contrast the -RAI group experienced a continued fall in BMD to 97.3% after one year, and 95.5% after 2 years, both reduced as compared to the +RAI group (P < 0.02). BMD of the hip also increased after RAI, to 102.3% after one year, and 101.7% after 2 years. In contrast BMD in the -RAI group decreased to 94.8% after one year, and 98.0% after 2 years, both lower than in the +RAI group (P < 0.01).

CONCLUSIONS

Subclinical hyperthyroidism due to a nodular goitre in postmenopausal women resulted in a continued loss of bone mass of about 2% per year. Radioiodine treatment resulting in normalization of serum TSH prevented this continued bone loss for at least 2 years. Our study supports earlier intervention in such patients.

Toxic nodular goiter. Toxic adenoma and toxic multinodular goiter

Solitary toxic adenoma and toxic multinodular goiter are very common forms of thyrotoxicosis around the world. Advances in molecular biology and genetics have led to new insights into the pathogenesis of these disorders. Current theories on autonomy in the thyroid are discussed in this article. The therapeutic roles of surgery, radioiodine ablation, and percutaneous ethanol administration also are reviewed.

Thyroid hormone treatment aiming at reduced, but not suppressed, serum thyroid-stimulating hormone levels in nontoxic goitre: effects on bone metabolism amongst premenopausal women

OBJECTIVES

To study the effects of six months' treatment with either T4 or T3, aiming at reduced but not totally suppressed serum TSH levels, as measured by a third generation TSH assay, on biochemical bone turnover parameters as well as bone mass in patients with nontoxic goitre.

DESIGN

Prospective randomized study with a matched control group, not blinded.

SETTING

Two University Hospital Clinics in Copenhagen.

SUBJECTS AND INTERVENTION

Twenty-four consecutive premenopausal women with moderate sized nontoxic goitre. Fourteen patients randomized to T4 or T3 treatment for six months with monthly titration of the dose, aiming at TSH values between 0.005 and 0.2 mUL(-1). Ten controls.

MAIN OUTCOME MEASURES

Serum parathyroid hormone (PTH), serum procollagen I C-terminal propeptide (PICP), serum alkaline phosphatase, serum osteocalcin, u-pyridinoline, u-deoxypyridinoline, u-hydroxyproline. Bone mass (BMD) at the lumbar spine and at both femoral necks.

RESULTS

Serum TSH was generally kept within the desired interval. There was no difference in any marker of bone metabolism between the effects of T4 and T3. Consequently, these groups were combined in order to evaluate the effect of thyroid hormones on the bone and mineral metabolism. Thyroid hormone treatment resulted in increased levels of serum ionized calcium (Ca) (P=0.02), serum alkaline phosphatase (P=0.007), serum-PICP (P=0.003), serum osteocalcin (P=0.02) and urinary excretion of deoxypridinoline (P=0.03) compared to untreated controls. Bone mass did not change.

CONCLUSION

Six months treatment with either T4 or T3 of premenopausal women with nontoxic goitre, aiming at reduced but not totally suppressed TSH values, resulted in biochemical signs of increased bone turnover, whereas bone mass remained unaltered. No differences were found between the effects of T4 or T3 treatment.

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.

Subclinical thyroid disease

Thyroid disease can roughly be divided into functional and anatomical disorders. Subclinical disease is by definition not accompanied by symptoms or signs and usually goes unrecognized for the bearer (and the observer). In this communication an overview will be given of existing literature and some own results concerning subclinical hypothyroidism, subclinical thyrotoxicosis and thyroid incidentalomas. Apart from definitions, data on prevalence, clinical effects, prognostic significance and the need for and response to therapy will be discussed.

Hip fractures and the thyroid: a case-control study

OBJECTIVE

To investigate the prevalence of thyroid illness - especially hyperthyroidism - and exposure to thyroid hormones in patients with hip fracture.

DESIGN

A case-control study.

SETTING

Two surgical/orthopaedic hospital units and 22 facilities for the aged in a moderately iodine-deficient region of Germany.

SUBJECTS

A total of 116 postmenopausal females with hip fracture and 402 postmenopausal female controls.

MAIN OUTCOME MEASURES

Hip fracture; thyroid disease confirmed by measurement of serum thyrotropin, total and free thyroxine and triiodothyronine; history of thyroid disease and thyroid medication obtained by a questionnaire.

RESULTS

Of the hip fracture patients 4.3% had overt untreated hyperthyroidism, and 6.9% gave a history of past hyperthyroidism (total, 11.2%). The corresponding figures for the controls were 2.0 and 2.7%, respectively (total, 4.7%). 7.8% of the cases had been exposed to levo-thyroxine for 3-29 years, compared to 11.2% of the controls. The odds ratio for hyperthyroidism (present and past) was 2.5 (1.2-5.3, 95% confidence interval), and the odds ratio for levo-thyroxine exposure was 0.67 (0.32-1.41) in the hip fracture patients.

CONCLUSIONS

Hyperthyroidism is found 2.5-fold more often in hip fracture patients than in controls. Hence, hyperthyroidism appears to be a significant risk factor for hip fracture and should be investigated by clinical and, when necessary, laboratory means in hip fracture patients. In contrast, no increased risk for hip fracture could be detected after exposure to levothyroxine.

Bone metabolism during anti-thyroid drug treatment of endogenous subclinical hyperthyroidism

OBJECTIVE

There is recent evidence that both exogenous and endogenous subclinical thyrotoxicoses are associated with decreased bone mineral density. Scanty information is available on bone metabolism in these conditions when euthyroidism is restored. We evaluated the effect of anti-thyroid drug treatment on bone metabolism in endogenous subclinical hyperthyroidism.

DESIGN

Prospective follow-up study over 2 years during treatment with methimazole, with an untreated control group.

SUBJECTS

Sixteen post-menopausal women with endogenous subclinical hyperthyroidism associated with multinodular goitre, eight of whom were treated with methimazole.

MEASUREMENTS

Serum concentrations of free T4, total T3, TSH, osteocalcin, urinary excretion of hydroxyproline and forearm bone mineral density were measured at regular intervals.

RESULTS

Significant changes in serum osteocalcin concentration or urinary hydroxyproline excretion were not observed in either group. Distal, but not proximal, forearm bone mineral density, expressed as a percentage of the base-line value, was significantly (P < 0.05) higher in the treated than in the untreated subjects in the second year of treatment.

CONCLUSION

Treatment with methimazole in post-menopausal women with endogenous subclinical hyperthyroidism associated with multinodular goitre can prevent excessive loss of bone, at least in the distal forearm.

Subclinical thyroid dysfunction in the elderly

Subclinical thyroid dysfunction is more common in older persons. By definition, these disorders are recognized by isolated elevation or suppression of the serum TSH concentration, in association with a normal serum free thyroxine level. Among individuals over 65 years old, subclinical hypothyroidism is found in approximately 10% of women and approximately 3% of men. It is most commonly due to autoimmune thyroiditis or previous treatment for hyperthyroidism. There may be three indications for L-thyroxine therapy: (a) presence of antithyroid antibodies, indicating substantial risk of progression to over hypothyroidism; (b) symptoms consistent with thyroid hormone deficiency; and (c) an elevated serum LDL-cholesterol. Subclinical hyperthyroidism is present in approximately 1%-2% of older persons. The most common cause is excessive thyroid hormone therapy, followed by mild endogenous hyperthyroidism due to Graves' disease or nodular goiter. These can be differentiated from other causes of low serum TSH concentration based on clinical and other laboratory and radionuclide scan criteria. The most serious consequences of subclinical hyperthyroidism are atrial fibrillation and osteoporosis, to which elderly patients are particularly predisposed.

Influence of clinical characteristics and parameters associated with thyroid hormone therapy on the bone mineral density of women treated with thyroid hormone

Reports of reduced bone mineral density (BMD) in patients receiving long-term replacement and suppression therapy with L-thyroxine have generated considerable interest and controversy. A substantial literature has evolved, with interpretation of conflicting results obscured by a variety of confounding factors. We examined the BMD measurements of 202 white women who were taking thyroid hormone to determine the contribution to BMD of a number of clinical characteristics and parameters associated with thyroid hormone therapy. Measurements of BMD (N = 335 over 2.6 +/- 1.6 years) of the spine (L2-L4) were performed in 195 subjects. The BMD of three sites of the hip was measured (N = 247 over 1.8 +/- 1.1 years) in 157 subjects. The BMD of the proximal radius was also measured (N = 172 over 1.8 +/- 1.2 years) in 124 subjects. Increasing age and a history of previous thyrotoxicosis had a deleterious effect on spine BMD. Body mass index (BMI) was positively correlated with spine BMD. Dose of thyroid hormone, duration of therapy, type of underlying thyroid disease, history of thyroidectomy, or serum-free thyroxine index did not influence either the initial BMD or the change in spine BMD over time. In the hip, age correlated with a decrease, and BMI with an increase in BMD. A history of previous thyrotoxicosis was associated with a decrease in hip BMD at all three sites (0.05 < p < 0.10). No other clinical parameters significantly influenced either the initial BMD or the change in hip BMD over time. Increasing age and dose of thyroid hormone, and a prior history of thyrotoxicosis had a deleterious effect on the BMD at the proximal radius. In summary, thyroid hormone therapy was not associated with a significant effect on BMD of the spine or hip, but a decreased BMD of the proximal radius was related to both previous thyrotoxicosis and to dose of thyroid hormone.

Hyperthyroidism, thyroid hormone therapy, and bone

Clinically symptomatic osteoporosis and fractures from thyrotoxicosis have been rare since the availability of antithyroid drugs and radioiodine for the treatment of hyperthyroidism. However, the widespread use of bone density measurements and sensitive TSH assays in the past decade has demonstrated that women taking levothyroxine with subclinical hyperthyroidism have reduced bone density. Cortical bone is affected more than trabecular bone, and postmenopausal women are at a greater risk than premenopausal women. However, it is uncertain whether subclinical hyperthyroidism is associated with an increased risk of fracture. Hypothyroidism is associated with an increase in cortical bone width. The initiation of levothyroxine treatment in hypothyroid women results in a reduction in cortical bone width to levels seen in euthyroid controls after 6-12 months. There is no reduction in bone density when women with subclinical hypothyroidism are treated with levothyroxine for a year. A single study showing reduced bone density in patients receiving chronic levothyroxine replacement therapy requires confirmation and raises an important question: Does levothyroxine replacement therapy, which results in higher serum thyroxine concentrations than those seen in euthyroid controls, accurately mimic physiology?

Prevalence of subclinical hyperthyroidism and relationship between thyroid hormonal status and thyroid ultrasonographic parameters in patients with non-toxic nodular goitre

OBJECTIVE

Basal plasma T4, T3 and TSH concentrations are usually normal in patients presenting with non-toxic nodular goitre. Using the evaluation of TSH response to TRH in a large series of such patients living in an area with normal iodine intake, we evaluated the prevalence of subclinical hyperthyroidism and the relationship between thyroid hormonal status and ultrasonographic parameters.

PATIENTS

A prospective study of 242 consecutive patients (group I), referred with non-autoimmune nodular goitre, normal plasma free T4, total T3 and TSH levels, without (subgroup IA, 222 patients) or with (subgroup IB, 20 patients) clear-cut autonomous area(s) on scintigraphy. These patients were compared to 135 controls (group II).

MEASUREMENTS

Plasma free T4 (FT4), total T3 (T3T) and TSH measurements. Evaluation of TSH response to TRH (delta level of increased TSH = peak TSH level during TRH test-basal TSH level), thyroid scintigraphy and morphological characteristics (number and total volume of nodule(s) and volume of extranodular tissue) determined by ultrasonography.

RESULTS

In subgroup IA, (1) the mean (+/- SEM) basal TSH level (0.94 +/- 0.04 mU/I) and the mean value of increased TSH after TRH (4.92 +/- 0.34 mU/I) were lower (P < 0.001) than in group II (1.28 +/- 0.05 mU/I and 7.24 +/- 0.25 mU/I, respectively). The prevalence of SH (delta level of increased TSH below the mean -3 SD in controls) was 17.2%; (2) the mean FT4 level and the mean T3T value were not different (P > 0.05) from those of group II. In subgroup IB, (1) the mean basal TSH level (0.57 +/- 0.11 mU/I) and the mean increment of TSH after TRH (2.81 +/- 0.62 mU/I) were lower (P < 0.001) than in subgroup IA. The prevalence of subclinical hyperthyroidism was 75.0%; (2) the mean FT4 level (17.2 +/- 0.9 pmol/I) was not different from that in group II. However, the mean T3T value (1.99 +/- 0.01 nmol/I) was higher (P < 0.001) than in group II (1.65 +/- 0.05). In group I, subgroup IA and IB, there were significant (P < 0.05, at least) correlations between the numbers of nodules and both basal TSH levels and delta values of increased TSH or FT4 levels or T3T values. No correlations were found between other ultrasonographic data and plasma thyroid parameters.

CONCLUSIONS

This study demonstrates a high prevalence of subclinical hyperthyroidism in patients presenting with non-toxic nodular goitres and suggests that the number of nodules, but not their total volume, is an important factor in the development of this condition.