This study indicates that the bone mineral density of the lumbar spine, femoral neck and the midshaft of the radius are not significantly decreased in premenopausal patients with endogenous subclinical hyperthyroidism resulting from a solitary autonomously functioning thyroid nodule. Conversely, findings hint at the possibility that long-lasting endogenous subclinical hyperthyroidism may be a contributing factor to the development of osteoporosis in some post-menopausal women, mostly at sites where cortical bone preponderates.

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Objective: Malignant tumors of the thyroid gland exhibit a variety of histopathologies and clinical behavior. Immune markers are gaining more and more importance in diagnostic pathology, especially in the differential diagnostics and in the grading of thyroid gland tumors. Design: The authors investigated the immunohistochemical reaction of galectin-3 (gal3) in patients with various thyroid gland diseases. They tested the diagnostic value of gal3 in determining the benign or malignant nature of various lesions, especially in lesions of follicular origin, because previous results have indicated nearly 100% specificity and sensitivity in this regard. Methods: Gal3 immunoperoxidase reaction was carried out on 91 sections of thyroid gland samples fixed in formalin and embedded in paraffin.

The mechanism by which thyroid hormones promote bone growth has not yet been elucidated. In vitro, thyroid hormones stimulate insulin-like growth factor-I (IGF-I) production by osteoblasts, which is important for the anabolic effects of the hormone on bone. To determine whether the IGF-I/IGF binding protein (IGFBP) profile is affected when thyroid hormone production is altered in vivo, we studied 36 women who had recently been diagnosed with hyperthyroidism (age: 29-67 years; 19 with Graves' disease, 17 with toxic nodular goiter) and 36 age-matched healthy women as controls. Serum IGF-I, and its binding proteins (IGFBP-3, IGFBP-4, and IGFBP-5), as well as bone mineral density (BMD) at the lumbar spine, femoral neck, and radius midshaft were measured before and 1 year after antithyroid (methimazole) treatment. Serum IGF-I levels were significantly increased in the hyperthyroid patients before treatment (214 +/- 18.2 ng/mL vs. 145 +/- 21.3 ng/mL; p < 0.05). There was no difference in IGF-I levels of patients with Graves' disease and toxic nodular goiter. Serum IGF-I concentrations returned to normal after treatment with methimazole. Serum IGFBP-3 and IGFBP-4 values were significantly elevated in the hyperthyroid group before treatment (3960 +/- 220 ng/mL and 749.7 +/- 53.1 ng/mL vs. 2701 +/- 180 ng/mL and 489.9 +/- 32.4 ng/mL; p < 0.05 and p < 0.01, respectively) and were reduced to those of controls after treatment. Serum IGFBP-5 of hyperthyroid subjects was not different from that of controls either before or after therapy. Serum free thyroxine showed a positive correlation with serum levels of IGF-I (r = 0.73, p < 0.05), IGFBP-3 (r = 0.59, p < 0.05), and IGFBP-4 (r = 0.67, p < 0.05) but not IGFBP-5. BMD at the radius midshaft was significantly lower in hyperthyroid patients at the start of the study and showed a positive correlation with serum IGF-I (r = 0.58; p < 0.001) and a negative correlation with IGFBP-4 (r = -0.61; p < 0.05). Radius BMD showed a 7.2% increase in the hyperthyroid group after 1 year of methimazole treatment, and the correlation between BMD and serum IGF-I disappeared. Our data indicate that thyroid hormones may influence the IGF-I/IGFBP system in vivo in hyperthyroidism. The anabolic effects of increased levels of IGF-I may be limited in hyperthyroidism due to the increases of inhibitory IGFBPs that can counteract the anabolic effects and contribute to the observed net bone loss.

Postmenopausal women with endogenous subclinical hyperthyroidism seem to have reduced bone mass, which does not correlate with serum thyroid hormone levels. Relative insufficiencies of IGF-I and dehydroepiandrosterone sulphate (DHEAS) might be additional risk factors for low bone density in these patients. We measured IGF-I, IGF-binding protein-3 (IGFBP-3) and DHEAS levels together with bone mineral density (BMD) of the femoral neck and lumbar spine in women with an autonomously functioning thyroid nodule. Sixty-three women were classified as subclinical hyperthyroid (31 pre- and 32 postmenopausal) and 39 as overt hyperthyroid (16 pre- and 23 postmenopausal) and results were compared with data obtained from 41 age-matched euthyroid healthy women. In premenopausal women BMD was reduced only in the overt hyperthyroid group, and only in the spine, to 92% (P < 0.05). Serum IGF-I as well as IGFBP-3 were increased in the manifest hyperthyroid group, to 157% (P < 0.001) and 129% (P < 0.05) respectively, whereas DHEAS levels did not change in either premenopausal patient group. In postmenopausal women BMD was significantly reduced both in the subclinical hyperthyroid group (spine to 90% and femoral neck to 88%; P < 0.05), as well as in the hyperthyroid group (spine to 78% and femoral neck to 86%; P < 0.01). In contrast to premenopausal women, serum IGF-I and IGFBP-3 did not change in the two groups who were postmenopausal and serum DHEAS levels were reduced to 58% (P < 0.001) in both postmenopausal groups with subclinical as well as overt hyperthyroidism. In the same two groups of patients, serum IGF-I and DHEAS levels correlated with BMD (femoral neck; both r = 0.50, P < 0.05). In conclusion, women with a solitary autonomous thyroid nodule with subclinical hyperthyroidism have reduced BMD only if they are postmenopausal. This is probably due to the effect of subtle increases in thyroid hormone production together with lack of oestrogen protection of the skeleton. But additional risk factors for the development of enhanced bone loss might be a state of relative IGF-I and DHEAS insufficiency in these patients as well as in postmenopausal women with overt hyperthyroidism.