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

Influence of thyroid hormone therapy on the fracture rate - A claims data cohort study

INTRODUCTION

It has been debated for years whether long-term thyroid hormone intake causes fractures. Not only have previous studies suffered from design limitations, they also reached contradictory conclusions. We investigated thyroid hormones (thyroxine) as a possible risk factor for fractures in a cohort of 6.7 million persons based on administrative data.

METHODS

The database consists of anonymized settlement data of approximately 70 German statutory health insurances covering a time period of six years. All subjects aged 60 and above were included in the study; subjects with repeated thyroxine prescriptions were assigned to the exposure group; members without thyroxine prescriptions to the control group. Outcome was any incident fracture during a declared time period. In order to calculate fracture risk, we performed multivariate cox regression analyses to adjust for confounders.

RESULTS

Of 798 770 subjects fulfilling the inclusion criteria, 11.7% took thyroxine regularly and belong to the exposure group. The final cox regression showed that subjects taking thyroxine have a 6.3% higher risk (HR 1.063; CI 1.046-1.080, p=<.0001) than members of the control group.

DISCUSSION

The study supports the assumption that long term thyroxine intake leads to an increase in fracture risk among patients older than 60years. The findings have implications for long term thyroxine treatment.

A longer interval without GH replacement and female gender are associated with lower bone mineral density in adults with childhood-onset GH deficiency: a KIMS database analysis

OBJECTIVE

Childhood-onset GH deficiency (COGHD) is associated with low bone mineral density (BMD). Adults with persistent COGHD may be at risk for insufficient bone accrual or bone loss during adulthood. The purpose of this study was to identify BMD predictors and to characterize the effects of GH replacement on BMD in COGHD adults with persistent GHD.

DESIGN

Retrospective analysis of the KIMS database.

METHODS

Variables predicting standardized BMD (sBMD) were identified. The effect of GH replacement (3 years) on BMD was examined.

RESULTS

Three hundred and fourteen COGHD adults (148 women, 166 men; 62 non-naïve, 178 semi-naïve, and 74 true naïve, depending on length and timing of previous GH replacement), who had BMD measured in lumbar spine (LS) and femoral neck (FN) at study entry. In semi-naïve subjects, a longer gap in GH replacement between childhood and adulthood was predictive of lower sBMD in the FN (r=-0.18, P=0.038). TSH deficiency predicted lower sBMD in the LS (r=-0.16, P=0.052). In true naïve patients, a longer gap between onset of pituitary disease and study entry (r=-0.35, P=0.012), and female gender (r=-0.27, P=0.043) independently predicted lower sBMD in the FN. There were no differences in BMD increases between non-naïve, semi-naïve, and true naïve subjects on GH replacement.

CONCLUSIONS

In semi-naïve subjects a longer interval off GH replacement was associated with lower sBMD in the FN. Among true naïve patients, a longer gap between the onset of pituitary disease and GH replacement, and female gender predicted lower sBMD in the FN.

Levothyroxine dose and risk of fractures in older adults: nested case-control study

OBJECTIVE

To quantify the effect of levothyroxine dose on risk of fractures in older adults.

DESIGN

Nested case-control study.

SETTING

Population based health databases, Ontario, Canada.

PARTICIPANTS

Adults aged 70 or more prescribed levothyroxine between 1 April 2002 and 31 March 2007 and followed for fractures until 31 March 2008. Cases were cohort members admitted to hospital for any fracture, matched with up to five controls from within the cohort who had not yet had a fracture.

MAIN OUTCOME MEASURE

Primary outcome was fracture (wrist or forearm, shoulder or upper arm, thoracic spine, lumbar spine and pelvis, hip or femur, or lower leg or ankle) in relation to levothyroxine use (current, recent past, remote). Risk among current users was compared between those prescribed high, medium, and low cumulative levothyroxine doses in the year before fracture.

RESULTS

Of 213,511 prevalent levothyroxine users identified, 22,236 (10.4%) experienced a fracture over a mean 3.8 years of follow-up, 18,108 (88%) of whom were women. Compared with remote levothyroxine use, current use was associated with a significantly higher risk of fracture (adjusted odds ratio 1.88, 95% confidence interval 1.71 to 2.05), despite adjustment for numerous risk factors. Among current users, high and medium cumulative doses (>0.093 mg/day and 0.044-0.093 mg/day) were associated with a significantly increased risk of fracture compared with low cumulative doses (<0.044 mg/day): 3.45 (3.27 to 3.65) and 2.62 (2.50 to 2.76), respectively.

CONCLUSION

Among adults aged 70 or more, current levothyroxine treatment was associated with a significantly increased risk of fracture, with a strong dose-response relation. Ongoing monitoring of levothyroxine dose is important to avoid overtreatment in this population.

Osteoporosis and thyrotropin-suppressive therapy: reduced effectiveness of alendronate

BACKGROUND

Many reports of the effect of exogenous thyroxine therapy on bone mineral density (BMD) show a relationship between excess thyroid hormone administration and osteoporosis. The aim of this study was to evaluate the effect of antibone resorptive agents, in particular alendronate (ALN) on BMD in postmenopausal osteoporotic women with thyroid carcinoma who were receiving long-term thyrotropin (TSH)-suppressive therapy with thyroxine.

METHODS

Seventy-four postmenopausal women with low BMD (T-score < or =-2.5) and differentiated thyroid carcinoma on long-term TSH-suppressive therapy (TSH > or =0.05 and < or =0.1 microU/mL) for about 3-9 years were selected for the study. The patients were divided into three groups according to the length of levothyroxine (LT(4)) treatment prior to the beginning of the study: group A (TSH-suppressive therapy for about 3 years), group B (for about 6 years), and group C (for about 9 years). These patients were compared with 74 matched women not taking LT(4). All patients and controls were treated with bisphosphonates, calcium, and vitamin D for 2 years and evaluated.

RESULTS

After 24 months of treatment group A showed a 7.8% increase in lumbar BMD; group B, a 4.6% increase; and group C, a 0.86% increase. In the control group BMD increased 8.2%. A significant difference was found in both lumbar and femoral BMD increase among the three groups: group C had a lower BMD increase than group A (p < 0.001) and B (p < 0.001).

CONCLUSIONS

In postmenopausal women who were receiving adequate amounts of calcium and vitamin D in their diet ALN was less effective for those who were also receiving TSH-suppressive doses of LT(4) for either 6 or 9 years. The positive effect of ALN on BMD was less for longer periods of LT(4) treatment. It seems likely that other bisphosphonates would also be less effective in increasing BMD in postmenopausal women receiving TSH-suppressing doses of LT(4).

Stress fracture and military medical readiness: bridging basic and applied research

PURPOSE

Military recruits and distance runners share a special risk of stress fracture injury. Recent efforts by US and Israeli military-sponsored researchers have uncovered important mechanisms and practical low-cost interventions. This article summarizes key findings relevant to prevention of stress fracture, including simple strategies to identify and to mitigate risk.

METHODS

Published research supported through the Bone Health and Military Medical Readiness research program and related military bone research was analyzed for contributions to preventing stress fracture in military recruits and optimizing bone health.

RESULTS

Thousands of military recruits helped test hypotheses about predictors of risk, safer exercise regimens, and rest, nutrition, gait training, and technology interventions to reduce stress fracture risk. Concurrent cellular, animal, and human laboratory studies were used to systematically investigate mechanisms of mechanical forces acting on bone and interactions through muscle, hormonal and genetic influences, and metabolism. The iterative and sometimes simultaneous process of basic discovery and field testing produced new knowledge that will provide safer science-based physical training.

DISCUSSION

Human training studies evaluating effects on bone require special commitment from investigators and funders due to volunteer compliance and attrition challenges. The findings from multiple studies indicate that measures of bone elasticity, fragility, and geometry are as important as bone mineral density in predicting fracture risk, with applications for new measurement technologies. Risk may be reduced by high intakes of calcium, vitamin D, and possibly protein (e.g., milk products). Prostaglandin E2, insulin-like growth factor 1, and estrogens are important mediators of osteogenesis, indicating reasons to limit the use of certain drugs (e.g., ibuprofen), to avoid excessive food restriction, and to treat hypogonadism. Abnormal gait may be a correctable risk factor. Brief daily vibration may stimulate bone mineral accretion similar to weight-bearing exercise. Genetic factors contribute importantly to bone quality, affecting fracture susceptibility and providing new insights into fracture healing and tissue reengineering.

Impact of total versus subtotal thyroidectomy on calcium metabolism and bone mineral density in premenopausal women

Objective:

This study aimed to compare the impact of total versus subtotal thyroidectomy on calcium metabolism and bone mineral density in euthyroid, premenopausal women.

Subjects:

The study included 24 premenopausal women who had undergone total (n = 10) or subtotal (n = 14) thyroidectomy and who were receiving nonsuppressive doses of thyroxine. The median post-operative period was four years. We determined, in all patients, the following parameters associated with calcium metabolism: total serum calcium, inorganic phosphate, intact parathormone, calcitonin and alkaline phosphatase. The bone mineral density of the spine and hip were measured using a Hologic QDR 4500C bone densitometer and were compared with controls matched for age and peak bone mineral density (using the t-test).

Results:

The measured calcium metabolism parameters were normal in all patients, and none had osteoporosis. There was no significant difference in the bone mineral density measurements for the spine and hip, comparing patients who had undergone total versus subtotal thyroidectomy (using the t-test).

Conclusion:

The impact of total thyroidectomy on bone mineral metabolism is not significantly different from that of subtotal thyroidectomy, in premenopausal women with normal thyroid-stimulating hormone values.

A study of dental implants in medically treated hypothyroid patients

PURPOSE

The purpose of this study was to investigate the success outcomes of implants and prosthodontic treatment placed in patients with a previous history of hypothyroidism that was being controlled with medications.

MATERIALS AND METHODS

Twenty-seven female patients with a medically confirmed history of primary hypothyroid disease who were on replacement medications at the time of implant surgery were selected as the study group. They were matched with 29 control patients by age, gender, location (jaw and zone) of implants, type of prosthesis, and dental status of the opposing arch. Additional factors studied were medical history, medications, smoking habits, and bone quality and quantity.

RESULTS

There was no statistical difference in the number of implant failures between the two groups (p = .781). The hypothyroid patients had more soft tissue complications (p = .018) following stage 1 surgery. More bone loss around implants in the hypothyroid patients was recorded after year 1 of loading when compared with loss in their matched controls (p = .017).

CONCLUSIONS

This study suggests that medically controlled hypothyroid female patients treated with dental implants are not at higher risk of implant failure when compared with matched controls, and that a history of controlled hypothyroidism does not appear to be a contraindication for implant therapy with endosseous implants.

Bone mineral density in pre-and post-menopausal women with affective disorder treated with long-term L-thyroxine augmentation

BACKGROUND

Augmentation with TSH-suppressive L-thyroxine (T4) has been shown to improve the course of illness in otherwise refractory affective disorders. This collaborative study investigates whether T4 augmentation for a minimum of 12 months decreases bone mineral density (BMD) in 26 pre- and post-menopausal women with affective disorder.

METHODS

We measured BMD at the femoral neck, Ward's triangle, trochanter and lumbar vertebrae (L1-L4) in 13 premenopausal and 13 postmenopausal women with affective disorder using dual energy X-ray absorptiometry. BMD was expressed as g/cm(2) and as a Z-score, calculated using bone density data from the international reference population standard.

RESULTS

The Z-scores for the pre- and post-menopausal women were within the reference range of the age and sex matched population standard. BMD for the composite group also did not differ either from the population standard. BMD in the lumbar spine and hip did not differ significantly between the pre- and post-menopausal groups. However, there were a relatively high number of postmenopausal patients with BMDs one S.D. lower than the population standard.

LIMITATIONS

This is a cross-sectional study with a relatively small sample size.

CONCLUSIONS

The study demonstrates that T4 augmentation treatment does not reduce BMD to a clinically significant degree in many women with affective disorder. However, the resilience of bone structure to T4 treatment may vary with site and menopausal status. This study underscores the need for regular assessment of BMD during adjunctive thyroid treatments for affective disorder, especially in postmenopausal women.

Osteoporosis due to cancer treatment: pathogenesis and management

Many therapeutic regimens in cancer treatment carry the risk of causing or favoring the development of osteoporosis. Therapies in which hypogonadism may occur are most relevant in this respect. Prompt hormone replacement therapy is indicated in these patients. In patients in whom this is undesirable because of a hormone-dependent tumor, the risk of osteoporosis should be assessed by means of osteodensitometry, and prophylactic or therapeutic measures should be instituted if necessary. Early intervention improves outcome because osteoporosis therapy is most effective in preventing deterioration of bone mass. There remains much uncertainty in assessing the risk of combination chemotherapy with regard to the development of osteoporosis. Negative effects on the skeleton have, however, been demonstrated for individual drugs, such as methotrexate and ifosfamide. Negative effects of the tumor itself on bone metabolism may aggravate the degree of osteoporosis. Detailed data and long-term experience to assess the risk are urgently needed in this area and constitute an important research topic for the coming years and decades. This review discusses the most prevalent mechanisms of osteoporosis caused by cancer treatment and outlines therapeutic strategies for the prevention and treatment of therapy-induced bone loss.

Long-term hypothyroidism causes decreased bone competence in male European starlings, Sturnus vulgaris

Male European starlings were thyroidectomised and held on either short or long day photoperiods. Intact euthyroid control birds were also held on either short or long days to control for differences in reproductive condition. Femora of birds from each group were sampled following plasma thyroxine measurement. Hypothyroidism caused decreased bone mechanical competence in starlings, as determined by Vickers microhardness testing. It was also found that transfer from short to long daylengths caused increased plasma thyroxine concentration, but that this did not affect bone mechanical competence. The finding that hypothyroidism causes decreased bone mechanical competence agrees with another animal study and a number of human studies, and we conclude that bone quality and mechanical competence can be adversely affected by abnormal thyroxine concentrations.

Changing concepts in the diagnosis and management of thyroid nodules

Thyroid nodules are extremely common, affecting from 4% to 7% of the population. Fine-needle aspiration biopsy is the most accurate and cost-effective technique for nodule diagnosis. It is simple, safe, and should be the first test used in patient work-up. Routine thyroxine (T4) suppressive therapy is no longer recommended for cytologically benign nodules. T4 suppression can cause or aggravate osteoporosis, especially in postmenopausal women. New data on T4 suppressive therapy, cost analysis, and nodule guidelines are reviewed.

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.

A longitudinal study of changes in body mass index and total body composition after radioiodine treatment for thyrotoxicosis

Patients treated for thyrotoxicosis often complain of increases in body weight after treatment of their thyroid disorder. The objective of this study was to define the extent of changes in body mass and composition following treatment of thyrotoxicosis with radioiodine 131I. We prospectively measured body mass index (BMI) in 75 patients (18 males, 57 females), ranging in age from 15-88 years treated for thyrotoxicosis with 131I (doses ranging from 5.2 to 25.7 mCi) between 1978 and 1994. BMI pre- and post-radioiodine treatment were recorded for up to 10 years after treatment. Body composition studies were performed on a subgroup of 9 patients (1 male, 8 females), aged 24 to 74 years treated with 6.0 to 12.2 mCi 131I. Bone mineral content, lean mass, and fat content were determined prior to and following 131I treatment through whole body scanning with a Hologic QDR-1000/W dual energy x-ray densitometer. Sustained increases in BMI averaging 2.33 kg/m2 above baseline (p < .01) were observed from the initial 6 months through the first 5 years after 131I therapy. BMI was no different from pretreatment levels over the remainder of the 10-year follow-up period. Lean mass increased significantly (p = .0004) by an average of 7.2 kg. Although both fat and mineral content appeared to increase, these changes were not statistically significant. Weight gain occurs within the first year after 131I treatment of patients with thyrotoxicosis and is predominantly due to increased lean mass (20.2%, p < .0005) although bone mineral content increased only marginally (4.62%, p = .10).

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.

Bone mineral density in adolescent females treated with L-thyroxine: a longitudinal study

It has been suggested that chronic treatment with L-thyroxine (L-T4) could be implicated in reducing bone mineral density (BMD). The purpose of this longitudinal study was to determine whether appendicular and axial BMD is decreased by L-T4 treatment in adolescent girls. Thirteen adolescent girls with subclinical hypothyroidism caused by chronic lymphocytic thyroiditis were enrolled in the study at the median age of 13.4 years (range 9.2-18.1 years). L-T4 was administered in a single dose of 1-5 micrograms/kg daily. BMD was evaluated at the distal one-third of the non-dominant radius by single photon absorptiometry (SPA) and at the lumbar spine (L2-4) by dual energy X-ray densitometry (DEXA). Osteocalcin levels were measured to assess bone turnover before and during L-T4 treatment. Before the start of therapy, mean BMD at both the radial and lumbar level was not significantly different from that of a control group (median age 13.0 years; range 9.0-18.5 years). during L-T4 therapy for 2-5 years, BMD did not change at any site. Before treatment, osteocalcin levels were not significantly different from those of controls and did not change during follow up.

CONCLUSION

Long-term L-T4 therapy in adolescent girls has no adverse effect on BMD and bone turnover. Our data indicate that attainment of peak bone mass is not impaired by L-T4 administration.

Subclinical thyroid disease

Widespread use of improved measurements for serum thyroid hormones and thyroid-stimulating hormone (TSH) has resulted in characterization of the syndromes of subclinical hypothyroidism, characterized by normal free T4 estimate and raised serum TSH, and subclinical hyperthyroidism, in which patients have normal serum free T4 estimate and decreased serum TSH. Therapy for these two disorders in generally recommended but must be individualized according to the patient's general medical condition. Additional studies are needed to assess the benefits of treatment. This report reviews subclinical hypothyroidism and subclinical hyperthyroidism, describing their causes, diagnostic criteria, complications, and indications for treatment. A brief review of testing for thyroid function is presented, and each of the subclinical disorders is compared with the classic syndromes of hypothyroidism and hyperthyroidism.

Controversies in the management of cold, hot, and occult thyroid nodules

Some aspects of thyroid nodule evaluation and management remain controversial. Radionuclide scanning provides functional information about nodules and differentiates cold from hot nodules. Although thyroid cancers are cold on scan, most cold nodules are benign. Ultrasonography visualizes the thyroid gland and nodules with remarkable clarity and provides structural information about location, number, size, and consistency of nodules. Widespread application of ultrasonography has resulted in the frequent discovery of incidental (occult) nodules in the general population. The clinical significance of these nodules remains unknown, and their management has created a dilemma for physicians. Current cost-effective evaluation of nodules does not include scanning or ultrasonography as routine frontline tests. In most centers, fine-needle aspiration biopsy has supplanted imaging studies as the routine initial procedure for differentiating benign from malignant nodules. Cytologic diagnosis is reliable and inexpensive, and it results in a better selection of patients for surgery. Limitations include false-negative diagnoses, nondiagnostic results, and indeterminate "suspicious" results. Laboratory test results are usually normal, but determination of serum thyrotropin may identify a hot nodule, and plasma calcitonin may help diagnose medullary thyroid carcinoma. Treatment of thyroid nodules is controversial. In some practices, benign colloid nodules are treated with suppressive doses of levothyroxine. Recent reports cast doubt on the efficacy of this approach, and it is no longer acceptable to select patients for surgical treatment on the basis of suppressive therapy. Furthermore, suppressive levothyroxine therapy may be associated with significant bone and cardiac side effects, especially in elderly patients and postmenopausal women. Our approach is observation for most patients, and we suggest a careful risk-benefit analysis when suppression is considered. Hot (autonomous) nodules can be treated with radioiodine, surgery, or ethanol injection. The use of sensitive thyrotropin assays has revealed that the "euthyroid" hot nodule is often associated with subclinical hyperthyroidism, warranting treatment if risks of osteoporosis are significant. Small (< 1.5 cm) occult nodules can be observed. Larger (> 1.5 cm) nodules can be selectively evaluated by ultrasonographically guided fine-needle aspiration. It is prudent to consider cost of care, risk-benefit analysis, and the low incidence of malignancy in thyroid nodules when diagnostic tests are selected and the treatment plan is outlined.

Possible limited bone loss with suppressive thyroxine therapy is unlikely to have clinical relevance

To determine the effect of suppressive doses of thyroxine (T4) on bone mass, we studied 50 women on suppressive doses of T4 for 3-27 years (mean of 11 years). Twenty-five had nontoxic goiter and 25 had well-differentiated thyroid carcinoma. Fifty controls were matched for age, menopausal status, and body mass index. Bone mineral density (BMD) was measured in the lumbar spine (LS), femoral neck (FN), trunk (TK), and extremities (EXT) by dual-energy X-ray absorptiometry (DXA). In addition, the trunk area was measured by neutron activation analysis and recorded as a calcium bone index (CaBI). Twenty-one patients were restudied with DXA measurements at a mean of 1.5 +/- 0.5 (1 SD) years. The total population of 50 patients showed no difference in bone mass from controls. In patients with nontoxic goiter, there was no evidence of any loss in bone mass. Cancer patients showed insignificant reductions of 2-5% in BMD of LS, FN, and TK and a significant 5% reduction in BMD of EXT, compared to controls, and a 12% reduction in CaBI compared to goiter patients. Cancer patients had a slightly higher (p < 0.001) mean daily dose of T4 than goiter patients (0.23 vs 0.15 mg/day) but had a similar degree of TSH suppression. BMD and CaBI values did not correlate with free T4 index) with the daily T4 dose, accumulative dose, or with duration of T4 therapy. There were no significant changes in bone mass in either goiter or cancer patients restudied after a mean of 1.5 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of suppressive doses of levothyroxine treatment on sex-hormone-binding globulin and bone metabolism

The adverse effects of suppressive thyroxine treatment have previously been investigated and conflicting results have been published. This study aimed at evaluating the effects of subclinical hyperthyroidism on the liver and bones. We investigated the action of thyroxine on the liver by measuring sex-hormone-binding globulin (SHBG) levels and on bone turnover by evaluating osteocalcin (BGP) in both pre- and postmenopausal women. We compared the levels of both proteins to those of untreated subjects matched for age, menopausal status, and weight. Bone mineral density (BMD) was evaluated by biphotonic absorptiometry only in postmenopausal women with estrogen replacement therapy (ERT) and compared to two postmenopausal estrogen-treated controls. Forty-five women with multinodular goiter (38) or postsurgical thyroid carcinoma (7) were studied. They had received LT4 for 3 to 5 years (150 +/- 34 micrograms/day for nontoxic multinodular goiter, 184 +/- 46 micrograms/day for thyroid carcinoma). All patients had normal free T3 concentrations. No significant difference was found in SHBG values between patients and controls whatever the menopausal status and the BMI; a significant increase in BGP was noted in premenopausal women (9.6 +/- 2.2 vs 6.7 +/- 2.3 ng/ml; p < 0.0006). No significant BGP and BMD variations were observed in treated postmenopausal women. In summary, the study of carefully matched patients and controls revealed that thyroxine treatment has no effect on SHBG levels.(ABSTRACT TRUNCATED AT 250 WORDS)