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Purpose: Vitamin D and osteoporosis in Graves’ disease (GD) have been examined in cross-sectional studies with divergent results. Here, we prospectively studied vitamin D metabolism and bone health in patients with newly diagnosed GD. Methods: Thirty consecutive patients with de novo overt thyrotoxicosis diagnosed with GD were included. At diagnosis, none of the patients were treated with vitamin D or anti-osteoporotic drugs. All patients were initially treated with antithyroid drugs. Blood samplings were taken at baseline and at 6 weeks, 3, 6, 12 and 24 months after treatment start. Serum levels of 25OHD3, 1,25OH2D3, calcium, parathyroid hormone (PTH), and C-terminal telopeptides of Type I collagen (CTX-I) were analysed. Bone mineral density (BMD) was measured at baseline, and 1 and 2 years after treatment initiation. Results: At diagnosis, patients with GD did not have vitamin D deficiency. There were no significant correlations between levels of 25OHD3 and thyrotoxicosis. Upon treatment of the thyrotoxicosis, serum calcium fell transiently, and PTH and 1,25OH2D3 increased. 25OHD3 fell within the normal range and stabilised at 6 months. CTX-I fell over 12 months, BMD increased significantly up to 2 years, p= 0.002, < 0.001 and 0.005 in the spine, left total hip and left femoral neck, respectively. Conclusions: The present data underline that thyrotoxicosis has a negative impact on bone health and demonstrate fine-tuned dynamics in bone and vitamin D metabolism. Upon treatment, bone health improved over a follow-up period of 24 months despite rising PTH. Increased conversion of 25OHD3 to 1,25OH2D3 occurs during treatment of GD.

Purpose: Serum thyroglobulin levels are often elevated in Graves’ disease (GD) and in most cases decrease during treatment. Its relation to Graves’ orbitopathy (GO) has not been clarified. Previously, a risk of GO has been linked to smoking, TSH receptor stimulation, high TSH-receptor antibodies (TRAb), low thyroid peroxidase and thyroglobulin antibodies (TPOAb, TgAb). Methods: We examined Tg levels in 30 consecutive patients with GD were given drug therapy (methimazole + thyroxine) for up to 24 months. GO was identified by clinical signs and symptoms. 17 patients had GO, 11 of whom had it at diagnosis while 6 developed GO during treatment. During the study, 5 subjects were referred to radioiodine treatment, 3 to surgery. The remaining 22 subjects (GO n= 12, non-GO n= 10) completed the drug regimen. Results: At diagnosis, Tg levels in GO patients (n= 11) were higher (84, 30–555 µg/L, median, range) than in non-GO patients (n= 19) (38, 3.5–287 µg/L),p= 0.042. Adding the 6 subjects who developed eye symptoms during treatment to the GO group (n= 17), yielded p= 0.001 vs. non-GO (n= 13). TRAb tended to be higher, while TPOAb and TgAb tended to be lower in the GO group. For the 22 patients who completed the drug regimen, Tg levels were higher in GO (n= 12) vs. non-GO (n= 10), p= 0.004, whereas TRAb levels did not differ. Conclusion: The data may suggest that evaluation of thyroglobulin levels in GD could contribute to identify patients at increased risk of developing GO. Possibly, thyroidal release of Tg in GD reflects a disturbance that also impacts retroorbital tissues.

CONTEXT: SHBG regulates free sex steroid levels, which in turn regulate skeletal homeostasis. Twin studies have demonstrated that genetic factors largely account for interindividual variation in SHBG levels. Glucuronidated androgen metabolites have been proposed as markers of androgenic activity. OBJECTIVE: Our objective was to investigate whether polymorphisms in the SHBG gene promoter [(TAAAA)n microsatellite and rs1799941 single-nucleotide polymorphism] are associated with serum levels of SHBG, sex steroids, or bone mineral density (BMD) in men. Design and Study Subjects: We conducted a population-based study of two cohorts of Swedish men: elderly men (MrOS Sweden; n ≅ 3000; average age, 75.4 yr) and young adult men (GOOD study; n = 1068; average age, 18.9 yr). MAIN OUTCOME MEASURES: We measured serum levels of SHBG, testosterone, estradiol, dihydrotestosterone, 5α-androstane-3α,17{szligbeta}-diol glucuronides, androsterone glucuronide, and BMD determined by dual-energy x-ray absorptiometry. RESULTS: In both cohorts, (TAAAA)n and rs1799941 genotypes were associated with serum levels of SHBG (P < 0.001), dihydrotestosterone (P < 0.05), and 5α-androstane-3α,17{szligbeta}-diol glucuronides (P < 0.05). In the elderly men, they were also associated with testosterone and BMD at all hip bone sites. The genotype associated with high levels of SHBG was also associated with high BMD. Interestingly, male mice overexpressing human SHBG had increased cortical bone mineral content in the femur, suggesting that elevated SHBG levels may cause increased bone mass. CONCLUSIONS: Our findings demonstrate that polymorphisms in the SHBG promoter predict serum levels of SHBG, androgens, and glucuronidated androgen metabolites, and hip BMD in men.

Abstract: Objective. To characterise the uptake of 18F in skeletal metastases from breast cancer using positron emission tomography (PET) and to relate these findings to the appearance on CT. Patients and design. PET with 18F and CT were performed in five patients with multiple skeletal metastases from breast cancer. The CT characteristics were analysed in areas with high uptake on the PET study. Dynamic PET imaging of the skeletal kinetics of the 18F-fluoride ion were included. Results. The areas of abnormal high accumulation of 18F correlated well with the pathological appearance on CT. Lytic as well as sclerotic lesions had markedly higher uptake than normal bone, with a 5–10 times higher transport rate constant for trapping of the tracer in the metastatic lesions than in normal bone. Conclusion. PET with 18F-fluoride demonstrates very high uptake in lytic and sclerotic breast cancer metastases.

Insulin-like growth factor I (IGF-I) has documented anabolic effects on osteoblasts, whereas its influence on osteoclasts and on bone resorption is unclear. We have investigated the effects of IGF-I on osteoclast recruitment and bone resorption in vitro. IGF-I (at and above 1 nM) stimulated the formation of multinucleated tartrate-resistant acid phosphatase positive cells in murine bone marrow cultures, incubated for 9 days. The number of multinucleated cells increased to 540 ± 160% of control (mean ± SEM) in cultures treated with 10 nM IGF-I. IGF-I (0.1–100 nM) had no effect by itself on 45Ca-release from prelabelled neonatal mouse calvarial bones. However, IGF-I (100 nM) had an inhibitory effect on bone resorption induced by prostaglandin E2and 1,25(OH)2D3. These findings indicate that IGF-I enhances the formation of osteoclasts-like cells in long-term bone marrow cultures. In bone organ cultures, however, IGF-I has an inhibitory effect on stimulated bone resorption, suggesting that IGF-I inhibits existing osteoclasts and, alternatively, that IGF-I interferes with the osteoblast-derived factor(s) that stimulate existing osteoclasts.

Summary It has been reported that osteoclastic function is regulated by calcium-induced alterations in cytoplasmic free calcium ([Ca2+]i), possibly through a specific receptor. We have investigated whether osteoclasts, isolated from neonatal rat long bones, possess the divalent cation-receptor that has been demonstrated on parathyroid cells. Studies with fura-2 loaded adherent single cells showed that an increase in extracellular Ca2+ ([Ca2+]e) from 0.5 mM to 10 mM resulted in an increase in [Ca2+]i in isolated rat osteoclasts, from a basal value of 94.7±16.2 to 150.6±22.4 nM (means±SEM; n=14). The shape and time course of the [Ca2+]i increase varied considerably from cell to cell. Less than half of the cells responded with a rapid transient increase whereas the rest responded with a slow increase that reached a plateau within 1–2 minutes. When [Ca2+]e was changed back to 0.5 mM, a slow decrease in [Ca2+]i was monitored. Immunohistochemical staining with two different monoclonal antibodies, recognizing the putative Ca2+ receptor on parathyroid cells, did not indicate any staining on freshly isolated rat osteoclasts. Thus, our data demonstrate that an increase in [Ca2+]e causes an elevation of [Ca2+]i in osteoclasts. This increase is not mediated via the putative cation-receptor found on parathyroid cells.

Abstract.: It is generally accepted that bone formation is depressed during corticosteroid treatment, but the effects of glucocorticoids on bone resorption are less well characterized. We have investigated the effects of short-term treatment with high-dose oral glucocorticoids on biochemical markers of bone turnover in 20 consecutive patients with asthma who sought help for acute respiratory obstruction in our emergency department. Serum concentrations of the carboxy-terminal cross-linked telopeptide of type 1 collagen (1CTP), reflecting bone resorption, and the carboxy-terminal propeptide of type 1 procollagen (P1CP), reflecting bone formation, were measured by radioimmunoassay. Changes of the circulating levels of the bone resorption marker 1CTP after treatment were age dependent with a significant negative correlation (r =−0.54, P= 0.01). The dependency on age remained when correcting, in a multiple linear regression analysis, for 1CTP levels at admission, weight, sex, and daily maintenance dose of inhaled glucocorticoids. Circulating levels of P1CP were suppressed in the whole group 1 week after initiation of glucocorticoid therapy, from 123.3 ± 10.2 ng/ml at admission to 88.1 ± 6.3 ng/ml after 1 week (P < 0.01). The changes in P1CP levels were not related to age. Our data indicate that bone formation is suppressed by glucocorticoids in all age groups, whereas the effect of glucocorticoids on markers of bone resorption is dependent on age.

The effects of mouse recombinantγ-interferon (γ-IFN) and indomethacin on bone resorption stimulated by bradykinin, Lys-bradykinin, Met-Lys-bradykinin, des-Arg9-bradykinin and prostaglandin E2 (PGE2) have been studied using cultures of neonatal calvarial bones and analyzing the release of45Ca from prelabelled bones as a paramenter of bone resorption. In addition, the effects ofγ-IFN and indomethacin on formation of PGE2 in bone cultures stimulated by bradykinin was analyzed. Indomethacin (1 μmol/l) totally abolished bradykinin (1 μmol/l) induced45Ca release. The inhibitory effect of indomethacin could be fully reversed by addition of PGE2 (1 μmol/l).γ-IFN (1000 U/ml) almost totally inhibited45Ca release stimulated by bradykinin (1 μmol/l), but the inhibitory effect could only be partially overcome by PGE2.γ-IFN and indomethacin also inhibited the stimulatory effects of Lys-bradykinin, Met-Lys-bradykinin and des-Arg9-bradykinin (1 μmol/l) on45Ca release. The stimulatory effects of PGE2 (1 μmol/l) on radioactive calcium mobilization was partially inhibited byγ-IFN (1000 U/ml), whereas indomethacin (1 μmol/l) was without effect. The inhibitory effect ofγ-IFN on45Ca release stimulated by bradykinin and PGE2 was dose-dependent with threshold for action at 3–30 U/ml. Comparative dose-response curves showed thatγ-IFN was most potent as inhibitor of bradykinin induced45Ca release. Bradykinin (1 μmol/l) significantly stimulated PGE2 formation by a mechanism that was completely inhibited by indomethacin (1 μmol/l).γ-IFN (1000 U/ml) partially inhibited the stimulatory effect of bradykinin on PGE2 formation. These data show that i)γ-IFN is a potent inhibitor of bone resorption induced by bradykinin and bradykinin analogues and ii) that the mechanism of action can be mainly explained by an inhibition of kinin induced prostaglandin biosynthesis. The results, however, also show thatγ-IFN can inhibit bone resorption by mechanisms unrelated to prostaglandin formation.

The influence of chronic and acute exposure to parathyroid hormone (PTH) on formation and breakdown of type I collagen, using two recently developed radioimmunoassays for serum PICP (the carboxyterminal propeptide of type I procollagen) and serum ICTP (the carboxyterminal telopeptide of type I collagen), have been evaluated. Fasting morning values were obtained from 18 women with primary hyperparathyroidism (HPT) and an equal number of age-matched, healthy controls. A 24-hour infusion of synthetic human parathyroid hormone (PTH 1-38) was performed in 14 healthy females. The patients with HPT had higher values for serum ICTP than the controls (6.0±3.0 and 4.1±2.1 μg/liter; P<0.05), whereas the serum PICP concentrations were not different (170±72 and 151±65 μg/liter; n.s.). During infusion of PTH in healthy subjects, there was an increase of the serum ICTP concentrations (from 3.6±1.3 to 4.4±1.8 μg/liter; P<0.001) whereas those of serum PICP decreased (from 185±78 to 118±42 μg/liter; P≤0.0001). The increase of serum ICTP during infusion of PTH was positively related to the increase of serum calcium and other indices of bone resorption, i.e., fasting urinary excretions of hydroxyproline and calcium. The decrease of serum PICP was also related to the changes of serum ICTP and hydroxyproline in urine, serum calcium, and alkaline phosphatase but not to osteocalcin, an established marker of osteoblastic activity. The findings support the fact that serum ICTP is a valuable method for evaluating bone resorption and is also easy to perform. Furthermore, the discordant results for the different markers of osteoblastic activity indicat that they reflect different functions of the cell.

The effects of retinoic acid (RA), and calcitriol are mediated by specific nuclear receptors (RARs and VDR, respectively). Induction of RAR and VDR responsive elements in target genes requires a cofactor, the retinoid-X-receptor (RXR), with its ligand 9-cis RA. We have previously demonstrated the expression of RARs and RXRs in osteoblasts, and herein investigated the effects of the retinoids all-trans RA and 9-cis RA alone and combined with calcitriol on bone resorption in vitro, measured by 45Ca-release from prelabeled neonatal mouse calvarial bones. All-trans RA and 9-cis RA were powerful stimulators of bone resorption and essentially equipotent. At threshold concentrations (1 nM) both 9-cis RA and at-RA markedly inhibited the resorption induced by calcitriol (1 pM). The findings are compatible with a physiological role for retinoids in bone metabolism.