Bone turnover markers, hip bone geometry parameters and metabolic syndrome in community overweight postmenopausal women / 中华内分泌代谢杂志

Objective:To explore the changes of bone turnover markers and geometric parameters of hip bone in overweight postmenopausal women with metabolic syndrome(MS), as well as the influence of MS components. To analyze the association of these factors with the risk of fracture.Methods:A total of 505 overweight postmenopausal female patients who underwent health check-up in Lianhu Community Service Center, Danyang City, Jiangsu Province from January to December 2017 were selected. According to the MS diagnostic criteria of the International Diabetes Federation(2009), the patients were divided into MS group( n=331)and non-MS group( n=174). Blood samples were collected to determine the level of procollagen type 1 N-terminal propeptide(P1NP)and carboxy-terminal cross-linked telopeptide of type 1 collagen(CTX). Bone mineral density and hip bone geometry parameters were tested with dual-energy X-ray absorptiometry and hip structural analysis software. Results:The incidence of osteoporotic fracture and hip fracture in MS group was significantly higher than that in non-MS group(21.1% vs 13.8%, 4.8% vs 1. 1%, P<0.05). However, the bone mineral density of lumbar vertebra 1-4, femoral neck, and total hip in MS group was significantly higher than that in non-MS group, which remained after adjusting for age( P<0.05), but the difference disappeared after further adjustment for body mass index( P>0.05). The P1NP, CTX, femur strength index(FSI), section modulus(SM), and cross-sectional area(CSA)of MS group were significantly lower than those of non-MS group, the buckling ration(BR)was significantly higher than that in non-MS group, and the differences were still statistically significant after adjusting for age and body mass index( P<0.05). There was no significant difference in bone mineral density of lumbar vertebra 1-4, femoral neck, total hip, P1NP, and CTX between fracture group and non-fracture group in patients with MS. But FSI, SM, cross-sectional moment of inertia(CSMI), and CSA were significantly lower, BR was significantly higher( P<0.05) and femur strength decreased in patients with fracture. Regression analysis showed that high BR was an independent risk factor for fracture risk, while high FSI, SM, CSMI, and CSA were protective factors. Multivariate linear regression analysis showed that wasit circumference, diastolic blood pressure, and fasting plasma glucose were the main MS components affecting bone mineral density, bone turnover indexes, and hip bone geometry parameters. Conclusions:Overweight postmenopausal MS patients had decreased bone turnover rate, femoral strength, and relatively poor bone quality. Hip bone geometry parameters can be used as one of the methods to assess fracture risk in MS patients. Waist circumference, diastolic blood pressure, and fasting blood glucose are the important MS components affecting bone mass and bone quality.

Site-Specific Difference of Bone Geometry Indices in Hypoparathyroid Patients

BACKGROUND: Hypoparathyroid patients often have a higher bone mineral density (BMD) than the general population. However, an increase in BMD does not necessarily correlate with a solid bone microstructure. This study aimed to evaluate the bone microstructure of hypoparathyroid patients by using hip structure analysis (HSA). METHODS: Ninety-five hypoparathyroid patients >20 years old were enrolled and 31 of them had eligible data for analyzing bone geometry parameters using HSA. And among the control data, we extracted sex-, age-, and body mass index-matched three control subjects to each patient. The BMD data were reviewed retrospectively and the bone geometry parameters of the patients were analyzed by HSA. RESULTS: The mean Z-scores of hypoparathyroid patients at the lumbar spine, femoral neck, and total hip were above zero (0.63±1.17, 0.48±1.13, and 0.62±1.10, respectively). The differences in bone geometric parameters were site specific. At the femoral neck and intertrochanter, the cross-sectional area (CSA) and cortical thickness (C.th) were higher, whereas the buckling ratio (BR) was lower than in controls. However, those trends were opposite at the femoral shaft; that is, the CSA and C.th were low and the BR was high. CONCLUSION: Our study shows the site-specific effects of hypoparathyroidism on the bone. Differences in bone components, marrow composition, or modeling based bone formation may explain these findings. However, further studies are warranted to investigate the mechanism, and its relation to fracture risk.

Femoral bone structure in Otsuka Long-Evans Tokushima Fatty rats

OBJECTIVES: Type 2 diabetes mellitus (T2DM) increases fracture risk despite normal to high levels of bone mineral density. Bone quality is known to affect bone fragility in T2DM. The aim of this study was to clarify the trabecular bone microstructure and cortical bone geometry of the femur in T2DM model rats. METHODS: Five-week-old Otsuka Long-Evans Tokushima Fatty (OLETF; n = 5) and Long-Evans Tokushima Otsuka (LETO; n = 5) rats were used. At the age of 18 months, femurs were scanned with micro-computed tomography, and trabecular bone microstructure and cortical bone geometry were analyzed. RESULTS: Trabecular bone microstructure and cortical bone geometry deteriorated in the femur in OLETF rats. Compared with in LETO rats, in OLETF rats, bone volume fraction, trabecular number and connectivity density decreased, and trabecular space significantly increased. Moreover, in OLETF rats, cortical bone volume and section area decreased, and medullary volume significantly increased. CONCLUSIONS: Long-term T2DM leaded to deterioration in trabecular and cortical bone structure. Therefore, OLETF rats may serve as a useful animal model for investigating the relationship between T2DM and bone quality.

IF EXERCISE DOES NOT INCREASE BONE MINERAL DENSITY, WHAT DOES IT CHANGE? / 体力科学

Exercise has been proposed as one strategy for improving or maintaining the structural competence of bone. In contrast with previous densitometric analysis using dual energy x-ray absorptiometry (DXA) which reported that areal bone mineral density (aBMD ; bone mineral content per projected area) increased with exercise, the studies using peripheral quantitative computed tomography (pQCT) revealed that an improvement in the mechanical properties of adult bone in response to exercise is related to negative changes in volumetric BMD (vBMD ; bone mineral content in a unit volume). Therefore, if exercise does not increase vBMD, what does it change? The pQCT studies showed that periosteal area and cortical area were significantly greater in trained bone, together with an increase in cortical thickness. Furthermore, by assessing geometric bone adaptation to mechanical loading, cortical thickness and the mechanical properties of trained and sedentary bone were compared along 64 directions centering the center of gravity of the bone on cross-sectional pQCT images. The differences in these parameters for both groups depended on the direction of measurement, suggesting that site-specific adaptation of bone to exercise is related to the geographical relation of bone to muscle. Thus, the improvement in the mechanical properties of bone in response to long-term physical exercise is related to geometric adaptation and not vBMD.