"Trabecular Bone Score" (TBS): an indirect measure of bone micro-architecture in postmenopausal patients with primary hyperparathyroidism.

BACKGROUND: Patients with primary hyperparathyroidism (PHPT) generally show reduced bone mineral density (BMD) at cortical sites with relatively preserved trabecular bone. However, the increased fracture risk at all skeletal sites suggests that areal BMD probably is not effective in capturing all the determinants of bone strength. "Trabecular Bone Score" (TBS) has been recently proposed as an indirect measure of bone micro-architecture. Our study was aimed to investigate TBS in patients with PHPT. METHODS: Seventy-three Caucasian postmenopausal women with PHPT and 74 age-matched healthy women (C) were studied. In all participants BMD at lumbar spine (LS) and at femoral sites (Neck-FN and total hip-TH) was measured by DXA and, in 67 patients and 34 C, also at the distal 1/3 of the radius (R). TBS was measured in the region of LS-BMD. Spine X ray was assessed in all patients. RESULTS: Mean TBS values were significantly reduced in PHPT (1.19 ± 0.10) compared to C (1.24 ± 0.09, p<0.01). Patients and controls did not differ for age, years since menopause (YSM), BMI, 25(OH)D serum levels, creatinine clearance, LS-BMD and FN-BMD. On the contrary, mean BMD values at both TH and R were significantly lower in PHPT patients compared to controls (p<0.01 and p<0.0001, respectively). In PHPT with vertebral fractures (VF+, n=29) TBS was significantly lower than in those without fracture (VF-, n=44)(1.14 ± 0.10 vs. 1.22 ± 0.10, respectively; p<0.01), whose TBS values did not differ from C. Mean TBS values in patients with (n=18) and without (n=55) non-vertebral fractures did not significantly differ (1.16 ± 0.09 vs. 1.20 ± 0.11). The presence of vertebral fractures was independently associated with the reduction of TBS (OR=0.003, 95% CI=0-0.534, p=0.028) and with YSM (OR=1.076, 95% CI=1.017-1.139, p=0.011), but not with age, the reduction of LS-BMD and the increase of BMI. The combination of YSM > 10 years plus TBS < 1.2 was associated with a significant risk of VF (OR=11.73, 95% CI 2.43-66.55, p<0.001). A TBS value <1.2 showed a better performance in individuating VF (sensibility 79.3%, specificity 61.4%, positive predictive value 57.5%, and negative predictive value 81.8%) in respect to YSM > 10 years. CONCLUSIONS: TBS seems to indirectly reflect an alteration of bone micro-architecture in postmenopausal women with PHPT.

Muscle strength and bone in healthy women: effect of age and gonadal status.

OBJECTIVE: The aim of this work was to examine the effects of age and menopause on muscle strength and on the muscle-bone interaction. DESIGN: One hundred ninety-four healthy women (mean age 49.8 ± 12.6 SD years) were assessed. Maximal Voluntary Contraction (MVC, Newton, N) by Hand Grip Dynamometer, bone mineral density at one third of the radius (R-BMD) by dual-energy X-ray absorptiometry (DXA) and phalangeal ultrasound by the DBM Sonic 1200 device were evaluated at the upper dominant limb. Ultrasonometric parameters considered were Amplitude-Dependent Speed of Sound (ADSoS) and Ultrasound Bone Profile Index (UBPI). RESULTS: MVC significantly decreased with age (r²=-0.12, p<0.005). For each level of age, fertile women had a greater MVC compared to postmenopausal women (r²=0.015, p<0.005).In the whole sample, a statistically significant correlation between MVC and R-BMD (r=0.354, p<0.001) and between MVC and ADSoS (r=0.294) and UBPI (r=0.311)(p<0.001 for both) were observed. CONCLUSIONS: We conclude that age and menopausal status significantly contributed to the reduction of muscle strength. The decline of muscular strength significantly correlated with quantitative and qualitative bone features.

Phalangeal quantitative ultrasound and bone mineral density in evaluating cortical bone loss: a study in postmenopausal women with primary hyperparathyroidism and subclinical iatrogenic hyperthyroidism.

Twenty-five postmenopausal women with primary hyperparathyroidism (PHPT) and 30 age-matched women with subclinical hyperthyroidism (sHTH) were studied to assess cortical bone loss. One hundred two healthy women were also recruited. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry at lumbar spine (LS), femoral neck (FN) and femoral total (FT), and at one-third of the radius (R). Amplitude-dependent speed of sound (ADSoS) and Ultrasound Bone Profile Index (UBPI) were also evaluated using phalangeal quantitative ultrasound (QUS). A significant correlation was found between QUS and BMD at LS (ADSoS, p < 0.05) and R (ADSoS and UBPI, p < 0.001) in controls. QUS significantly correlated with BMD at LS, FN (p < 0.01), and FT (p < 0.001) in sHTH. No correlations were found in the PHPT group. Mean T-score values of all parameters were significantly lower in patients compared with controls (p < 0.001); however, they did not differ between PHPT and sHTH patients. T-score of R, ADSoS, and UBPI was reduced compared with other sites (p < 0.001) in both diseases. In postmenopausal women with PHPT and sHTH, bone loss is mainly detectable at cortical level. However, qualitative and/or structural changes of bone could account for the lack of correlations between these 2 techniques at cortical sites.

Vitamin D status as the major factor determining the circulating levels of parathyroid hormone: a study in normal subjects.

We investigated the relative contribution of the major factors regulating calcium homeostasis in determining the circulating levels of PTH. We studied 137 males and 125 females who were healthy volunteers. Circulating PTH levels were determined by three different immunoradiometric assays (IRMA). The first one (PTH Sorin, PTH S) utilizes two affinity-purified polyclonal antibodies directed against the 1-34 and 39-84 sequence of the hormone. The two other IRMA share polyclonal anti-PTH (39-84) antibodies. The first assay (PTH Whole, PTH W) utilizes a second polyclonal antibody, directed against the 1-4 amino acid sequence. The second assay (PTH Total, PTH T) utilizes a second antibody specific for the 7-34 region. Concentrations of PTH fragments lacking the initial amino acid sequence (PTH N-truncated, PTH N-t) were determined by the difference of values between PTH T and PTH W. Vitamin D was the main explicative variable almost in every multiple linear regression model, both considering the group as a whole (PTH S: R2 = 0.238, P < 0.0001; PTH W: R2 = 0.08, P < 0.001; PTH T: R2 = 0.145, P < 0.0001; PTH N-t: R2 = 0.081, P < 0.009) and when considering men and women separately. In subjects with vitamin D insufficiency (n = 53) [25(OH)D < 30 nmol/l], mean serum levels of parathyroid hormone were significantly higher (P < 0.001) than those in subjects of similar age with normal vitamin status (n = 209) with all the assays employed. This study demonstrates the central role of 25(OH)D in regulating PTH secretion in physiological conditions.