25-hydroxy vitamin D levels in healthy premenopausal women: Association with bone turnover markers and bone mineral density

BackgroundVitamin D deficiency is very common in elderly people while there are very few reports on its incidence, determinants and metabolic consequences in young subjects.ResultsIn 608 young healthy premenopausal women participating in the BONTURNO study, levels of 25-hydroxyvitamin D [25(OH)D] below 20 ng/ml were found in almost a third of the women. Its levels were inversely (P < 0.001) related with age and body mass index (BMI kg/m²) and directly with sunlight exposure during the summer time, and latitude: i.e. the higher the latitude over Italy, the higher the 25(OH)D level. In women on contraceptive pill the mean 25(OH)D level was significantly increased even when the data were adjusted for age, BMI and sun exposure.25(OH)D levels, adjusted for age and BMI, were significantly and positively related with serum C-telopeptide of type 1 collagen, serum phosphate and spine bone mineral density (BMD) and negatively with serum PTH, serum magnesium, serum bone alkaline phosphatase (bone AP).ConclusionVitamin D deficiency is rather common in young otherwise healthy Italian women and particularly among those living in the Southern part of the country. The most close determinants of vitamin D deficiency were BMI and sunlight exposure. Vitamin D insufficiency is associated with low spine BMD and increased bone AP even in young individuals.     

Association of bone turnover markers and arterial stiffness in pre-dialysis chronic kidney disease (CKD)

Vascular calcification (VC) is highly prevalent in CKD and leads to increased vascular stiffness and cardiovascular disease (CVD). Non-traditional cardiovascular risk factors include abnormal bone turnover and/or dysregulation of the calcification inhibitors, although their relative contribution remains unclear. We investigated the association between bone turnover, the calcification inhibitors (matrix gla protein; MGP and Fetuin-A), and the phosphate regulating hormone; fibroblast growth factor-23 (FGF-23) and arterial stiffness in pre-dialysis CKD patients. One hundred and forty-five patients with CKD stages 1-4 (74 M, 71 F) aged (mean [SD]) 53 [14] years were studied. Bone turnover markers (bone-specific alkaline phosphatase (BALP) and tartrate-resistant acid phosphatase (TRACP)) and MGP, Fetuin-A and FGF-23 were determined. BMD was measured at the lumbar spine (LS), femoral neck (FN), forearm (FARM) and total hip (TH). Arterial stiffness was assessed by contour analysis of digital volume pulse (SI(DVP)). There was a significant positive correlation between TRACP:BALP ratio and SI(DVP) ( r=0.19, p=0.023). Following multi-linear regression analysis, significant associations were seen between serum BALP (p=0.037), TRACP (p=0.009) and TRACP:BALP ratio (p=0.001) and SI(DVP) independently of traditional CVD risk factors. No significant relationship between SI(DVP) and MGP, Fetuin-A and FGF-23 was observed. A significant negative correlation was seen between BMD at the FARM and SI(DVP) in CKD stage 4 (r=-0.35, p=0.024). The association remained significant following correction for age, gender and cardiovascular risk factors (p=0.029). Our data suggest a link between imbalances in bone turnover and arterial stiffness in pre-dialysis CKD. Longitudinal studies are needed to evaluate the clinical usefulness of these bone turnover markers as predictors of CVD in CKD.     

Effects of vitamin E on bone turnover markers among US postmenopausal women

Increased oxidative stress and inflammation resulting from aging and declining estrogen levels can lead to increased bone loss in postmenopausal women. Alpha‐tocopherol and gamma‐tocopherol, the two predominant isomers of vitamin E, have antioxidant and anti‐inflammatory properties, but their effects on bone metabolism have not been well studied in humans. We examined the associations between dietary and total (diet and supplements) alpha‐tocopherol intake, serum alpha‐tocopherol and gamma‐tocopherol levels and their ratio, and bone turnover markers (BTMs) among postmenopausal women aged ≥45 years. We used cross‐sectional data from the National Health and Nutrition Examination Survey 1999–2002. Multiple regression models with adjustments for relevant confounders were used to examine the associations between intake and serum levels of tocopherols, and serum bone‐specific alkaline phosphatase (BAP), a biomarker of bone formation, and urinary N‐telopeptides/creatinine (uNTx/Cr), a biomarker of bone resorption. The study sample included 497 postmenopausal women who were not taking estrogen, steroids, or osteoporosis medications, were free from kidney and liver disease, cancer, and rheumatoid arthritis, and were fasting >9 hours prior to examination. Participants had a mean age of 65.5 ± 0.6 years and over 45% used vitamin E (alpha‐tocopherol) supplements in the past month. Vitamin E supplement users had significantly lower serum gamma‐tocopherol, higher serum alpha‐tocopherol levels, and higher ratio of serum alpha‐tocopherol to gamma‐tocopherol than nonusers. High serum gamma‐tocopherol levels and low ratio of serum alpha‐tocopherol to gamma‐tocopherol were associated with increased BAP levels (p < 0.01 for both). There were no associations between any of the vitamin E variables and uNTx/Cr. In conclusion, we hypothesize that gamma‐tocopherol may uncouple bone turnover, resulting in more bone formation than resorption. Vitamin E supplements in the form of alpha‐tocopherol suppress serum gamma‐tocopherol levels and may have negative effects on bone formation. Further research is needed to investigate the potential anabolic effect of gamma‐tocopherol from food sources on bone. © 2012 American Society for Bone and Mineral Research.     

Evaluation of cytokines regulating bone turnover in the serum of post-menopausal and senile women.

The authors evaluated the Insulin-like Growth Factor-1 (IGF-1) stimulating the formation of bone tissue, and interferon gamma (IFN gamma), inhibiting bone resorption, in the serum of women, 13 of fertile age, 34 of post-menopausal age, and 14 of senile age. Values for IGF-1 in the serum were considerably low in patients of post-menopausal and senile age, and presented highly significant differences with values for subjects of fertile age. The values for IFN gamma did not present significant differences between different age groups. It may be assumed that post-menopause and during senile age physiological osteopenia may be favored by a decrease in the secretion of IGF-1.     

Circulating osteoprotegerin in women during GnRH-agonist treatment and their relationships with mineral components and biomarkers of bone turnover

A novel cytokine termed osteoprotegerin (OPG) that is also called osteoclastogenesis-inhibitory factor, which inhibits osteoclast maturation and activity, was recently isolated. In order to determine the influence of estrogen deficiency on the levels of circulating OPG in women, we studied the changes in the levels of circulating OPG in 10 Japanese women ages 25-49 (mean +/- SD, 34.0 +/- 6.9) years with endometriosis receiving gonadotropin-releasing hormone agonists (GnRH-a) therapy. We further analyzed whether the levels of circulating OPG have relations with the levels of the biomarkers of bone turnover or those of circulating mineral components in these patients during GnRH-a treatment. The patients were treated with a monthly injection of 3.75 mg leuprolide acetate depot for 6 months. In all patients, the concentrations of serum estradiol decreased after 6 months of GnRH-a treatment. The bone mineral density of the lumber spines in these patients significantly (P < 0.01) decreased (percentage change: mean +/- SD, -5.4 +/- 2.1%), while circulating OPG levels significantly (P < 0.01) increased after 6 months of treatment. The values of circulating OPG had significant correlations with those of urinary pyridinoline (r = 0.59, P < 0.01), urinary deoxypylridinoline (Dpd) (r = 0.46, P < 0.05), and serum alkaline phosphatase (r = 0.66, P < 0.01) but not with those of serum carboxy-terminal propeptide of type I procollagen during GnRH-a treatment. The values of circulating OPG also correlated significantly with those of serum calcium (Ca) and phosphorus (P) (r = 0.65 and 0.72, P < 0.01). Further analyses revealed that the percentage change in the value of circulating OPG had a significant correlation with that of urinary Dpd (r = 0.84, P < 0.01). These results suggest that circulating OPG levels rise against the increase in osteoblastic bone resorption and circulating Ca levels in the case of estrogen deficiency, possibly as a compensatory mechanism serving to limit circulating Ca levels and bone density.     

Association between bone indices assessed by DXA,HR-pQCT and QCT scans in post-menopausal women

Quantitative computed tomography (QCT), high-resolution peripheral QCT (HR-pQCT) and dual X-ray absorptiometry (DXA) scans are commonly used when assessing bone mass and structure in patients with osteoporosis. Depending on the imaging technique and measuring site, different information on bone quality is obtained. How well these techniques correlate when assessing central as well as distal skeletal sites has not been carefully assessed to date. One hundred and twenty-five post-menopausal women aged 56–82 (mean 63) years were studied using DXA scans (spine, hip, whole body and forearm), including trabecular bone score (TBS), QCT scans (spine and hip) and HR-pQCT scans (distal radius and tibia). Central site measurements of areal bone mineral density (aBMD) by DXA and volumetric BMD (vBMD) by QCT correlated significantly at the hip (r = 0.74, p < 0.01). Distal site measurements of density at the radius as assessed by DXA and HR-pQCT were also associated (r = 0.74, p < 0.01). Correlations between distal and central site measurements of the hip and of the tibia and radius showed weak to moderate correlation between vBMD by HR-pQCT and QCT (r = ?0.27 to 0.54). TBS correlated with QCT at the lumbar spine (r = 0.35) and to trabecular indices of HR-pQCT at the radius and tibia (r = ?0.16 to 0.31, p < 0.01). There was moderate to strong agreement between measuring techniques when assessing the same skeletal site. However, when assessing correlations between central and distal sites, the associations were only weak to moderate. Our data suggest that the various techniques measure different characteristics of the bone, and may therefore be used in addition to rather than as a replacment for imaging in clinical practice.     

Osteoprotegerin: a valid new marker of bone turnover in post-menopausal osteoporosis?

Abstract An increase of setum osteoprotegerin has been found in post-menopausal women, that is positively correlated with age and bone markers, negatively with bone mass. In 25 post-menopausal women (mean age, 63±8 years) we measured serum levels of osteoprotegerin, total and bone alkaline phosphatase, osteocalcin, urinary deoxypyridinoline and bone mineral density of the lumbar spine and femur.Osteoprotegerin and bone markers did not differ from range of normal values. Bone mineral density appeared markedly reduced both at the spine and the femur.A significant correlation between osteoprotegerin and age, duration of menopause, osteocalcin and bone alkaline phosphatase was found. No correlation was found between osteoprotegerin and bone mineral density in all measured skeletal sites. In conclusion, osteoprotegerin does not appear to be an interesting parameter for the evaluation of bone turnover in post-menopausal osteoporosis.     

Association of non-invasive hemodynamics with arterial stiffness in rheumatoid arthritis

Objectives. Arterial stiffness has emerged as a surrogate marker of cardiovascular disease. We investigated the role of myocardial performance and hemodynamic parameters in arterial stiffness in patients with rheumatoid arthritis (RA), which is accompanied by excess cardiovascular risk. Design. Arterial stiffness was evaluated with pulse wave velocity (PWV) in RA patients and controls. Cardiac and hemodynamic characterization was based on impedance cardiography. Cardiovascular risk factors, inflammatory markers and disease-related parameters were assessed. Results. PWV (8.2?±?2.1 vs 7.4?±?1.4 m/s, p?=?.016) was higher among RA patients (n?=?104) compared to controls (n?=?52). In the RA group, PWV correlated with markers of cardiac contractibility (acceleration and velocity index), myocardial blood flow (cardiac output and stroke volume), preload (thoracic fluid content) and afterload (systemic vascular resistance) (p?<?.05 for all). PWV tended to increase with decreasing oxygen delivery to the myocardium (r?=?0.055), as well as with shortening of the ejection duration of the left ventricle (p?=?.058). However, these associations no longer remained significant after adjustment for classical cardiovascular risk factors, inflammation and corticosteroid use, which were independently associated with PWV. Conclusions. Among patients with RA, arterial stiffness appears as the composite of cardiovascular risk factors and inflammation, while corticosteroid use emerges as an additional adverse factor.     

Association between vitamin D and bone mineral density in Iranian postmenopausal women

The role of vitamin-D in determining bone mineral density (BMD), especially in less severe vitamin D deficiency, is still unclear. To investigate the possible association between 25-hydroxyvitamin D [25(OH)D] and BMD, 245 healthy free-living postmenopausal women, aged between 40 and 80, were randomly selected from participants of a population-based study. BMD was measured at the lumbar spine and hip by dual X-ray absorptiometry (Lunar DPXMD 7164). Serum 25(OH)D, parathyroid hormone (PTH), calcium, phosphorus, total and bone alkaline phosphatases, and urine deoxypyridinoline were measured. PTH was logarithmically transformed (LnPTH). Linear regression models were developed to determine the association between serum 25(OH)D and BMD at different sites. Means of age and duration of menopause were 57.7 +/- 7 and 9.4 +/- 6.8 years, respectively. Mean 25(OH)D was 73.0 +/- 62.3 nmol/l; 5.3% (n = 13) had 25(OH)D < 25 nmol/l and 37.6% (n = 92) had 25(OH)D between 25 and 50 nmol/l. Eleven percent of the women (n = 27) were osteoporotic in femoral neck and 25.3% of them (n = 62) were osteoporotic in lumbar spine sites. 25(OH)D correlated inversely with LnPTH (r = -0.25, P < 0.01). In the multivariate analyses, no association was found between 25(OH)D and BMD at any of the skeletal sites after adjusting for age, duration of menopause, body mass index, calcium, and LnPTH. However, BMD was associated inversely with LnPTH only in femoral neck but not in the other sites. This study did not show any association between 25(OH)D and BMD in free-living Iranian postmenopausal women.     

Association between pharmacokinetics of oral ibandronate and clinical response in bone mass and bone turnover in women with postmenopausal osteoporosis.

Data from the 1-year, phase II trial of oral ibandronate for treatment of postmenopausal osteoporosis are presented (n = 180). Participants were at least 10 years past menopause and had osteopenia defined as a forearm bone mineral density at least 1.5 SD below the premenopausal mean value. Doses were 0.25, 0.50, 1.0, 2.5, or 5.0 mg daily oral ibandronate or placebo. A total of 116 women treated with ibandronate completed the study. Blood samples for pharmacokinetic analyses were drawn 20 min, 40 min, 60 min, 2 h, 4 h, and 6 h after the first and last administration of the study drug. An enzyme-linked immunosorbent assay was used to determine the concentration of ibandronic acid (BM 21.0955) in serum (Enzymun-Test System ES 600). The assay is based on streptavidine technology to fix the capture antibody to the wall of the tube. Standards were prepared for each participant using individual drug-free serum. The serum concentration-time curves of ibandronate, expressed as the area under the curve over the sampling period (AUC(0-6h)), revealed a highly significant dose-response relationship, p < 0.0001, and linear pharmacokinetic behavior. An initial half-life (T(1/2lambda1)) in serum representing distribution and early elimination was 1.3 hours. Steady-state AUC (AUC(0-6h ss)) increased by a factor of 2.5, which is consistent with an apparent elimination half-life of 32.6 h and a dosing interval of 24 h. There was an exponential association between AUC(0-6h) (ss) and the change from baseline at month 12 in the bone markers (n = 116): r = -0.37 (serum total osteocalcin), r = -0.65 (urine C-telopeptides of type I collagen), and r = -0.65 (serum C-telopeptides of type I collagen), all p < 0.0001. All bone markers were maximally depressed at values of AUC(0-6h ss) of about 3 ng h/mL. AUC(0-6h ss) furthermore revealed a logarithmic association with change from baseline at month 12 in spine BMD, r = 0.39, p < 0.0001. In conclusion, the serum concentration of ibandronate was determined validly by the enzyme-linked immunosorbent assay. The data are the first to show highly significant associations between pharmacokinetic parameters of a bisphosphonate and the clinical response in bone mass and bone turnover.     

Association between bone mineral densities and serum lipid profiles of pre- and post-menopausal rural women in South Korea

The objectives of this population-based study were to investigate the potential association between bone mineral density (BMD) and serum lipid profiles and to compare the effects of serum lipids on BMD at various skeletal sites in pre- and post-menopausal women. In July and August of 2004, BMD was measured at a variety of skeletal sites [lumbar spine (L_1–4), femoral neck, trochanter, Wards triangle, shaft and proximal total hip] using the GE/Bravo Lunar DPX dual-energy X-ray absorptiometer in a South Korean population-based sample of 375 pre-menopausal and 355 post-menopausal rural women aged 19–80 years. The levels of serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were inversely associated with BMD in both pre- and post-menopausal women. In the pre-menopausal women, correlations were shown only for lumbar 1–4 (TC: r =–0.12, P <0.05; LDL-C: r =–0.12, P <0.05), whereas in the post-menopausal women, no correlation was evident for the lumbar sites. In the post-menopausal subjects, the TC levels showed significant correlations with the BMD values at the trochanter ( r =–0.15, P <0.01), shaft ( r =–0.16, P <0.001) and proximal total hip ( r =–0.15, P <0.01) sites, while the LDL-C levels showed significant correlations with the BMD values at the neck ( r =–0.13, P <0.05), trochanter ( r =–0.21, P <0.001), shaft ( r =–0.20, P <0.001) and proximal total hip ( r =–0.20, P <0.001) sites. The levels of triglyceride (TG) were shown to have a significant positive correlation with BMD values at the trochanter site ( r =0.11, P =0.05) in the post-menopausal women; by contrast, subjects in a higher quartile of TG levels show lower lumbar BMD values in the pre-menopausal women. The levels of high-density lipoprotein cholesterol (HDL-C) were not associated with BMD values at any of the sites in the pre- and post-menopausal subjects. Our data indicate a relationship between BMD values and serum lipid levels and suggest differences between pre- and post-menopausal women in terms of the effects of serum lipids on BMD at various skeletal sites.     

绝经后女性2型糖尿病患者骨密度及骨标志物水平研究

目的探讨绝经后女性2型糖尿病患者的骨密度及骨标志物水平。方法选择2014年12月~2016年3月在309医院骨内科住院的绝经后女性患者128例,其中2型糖尿病者60例为研究组,年龄50-69岁,平均年龄60.8岁,无糖尿病者68例为对照组,年龄50-69岁,平均年龄59.8岁,采用美国好乐杰公司双光能骨密度仪测量所有患者腰椎L2-L4和左侧股骨近端及全髋骨密度,并测定其身高、体重、体重指数(BMI),记录其入院时生化指标如血脂,血钙、磷、镁、空腹血糖情况,采用酶联免疫吸附法测定各组的B-ALP、CTX、PINP、25羟维生素D的水平,比较两组间骨密度值、生化指标及骨标志物水平是否存在统计学差异。结果两组间一般情况如年龄、身高、体重、总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇、血镁、血脂水平无统计学差异,两组髋部及腰1-4椎体骨密度水平、25羟维生素D及PTH无统计学差异。观察组空腹血糖、血钙水平、骨代谢标志物CTX高于对照组,而OC、ALP低于对照组,差异具有统计学意义。结论绝经后2型糖尿病妇女骨转换标志物异常,可能是预测糖尿病性骨质疏松的一个标志。     

The relationship between vitamin D and parathyroid hormone: calcium homeostasis, bone turnover, and bone mineral density in postmenopausal women with established osteoporosis

It is evident from several studies that not all patients with hypovitaminosis D develop secondary hyperparathyroidism. What this means for bone biochemistry and bone mineral density (BMD) remains unclear. The aim of this study was to investigate the effects of hypovitaminosis D (defined as a 25OHD < or = 30 nmol/l) and patients with a blunted PTH response (defined arbitrarily as a PTH within the standard laboratory reference range in the presence of a 25OHD < or = 30 nmol/l) in comparison to patients with hypovitaminosis D and secondary hyperparathyroidism (defined arbitrarily as a PTH above the standard laboratory reference range in the presence of a 25OHD < or = 30 nmol/l) and vitamin D-replete subjects (25OHD > 30 nmol/l). Four hundred twenty-one postmenopausal women (mean age: 71.2 years) with established vertebral osteoporosis were evaluated by assessing mean serum calcium, 25OHD, 1,25(OH)2D, bone turnover markers, and BMD. The prevalence of hypovitaminosis D was 39%. Secondary hyperparathyroidism was found in only one-third of these patients who maintained calcium homeostasis at the expense of increased bone turnover relative to the vitamin D-replete subjects (bone ALP mean difference: 43.9 IU/l [95% CI: 24.8, 59.1], osteocalcin: 1.3 ng/ml [95% CI: 1.1, 2.5], free deoxypyridinoline mean difference: 2.6 nmol/nmol creatinine [95% CI: 2.5, 4.8]) and bone loss (total hip BMD mean difference: 0.11 g/cm2 [95% CI: 0.09, 0.12]). Patients with hypovitaminosis D and a blunted PTH response were characterized by a lower serum calcium (mean difference: 0.07 mmol/l [95% CI: 0.08, 0.2]), a reduction in bone turnover (bone ALP mean difference: 42.4 IU/l [95% CI: 27.8, 61.9], osteocalcin: 1.6 ng/ml [95% CI: 0.3, 3.1], free-deoxypyridinoline mean difference: 3.0 nmol/nmol creatinine [95% CI: 1.9, 5.9]), but protection in bone density (total hip BMD mean difference: 0.10 g/cm2, [95% CI: 0.08, 0.11]) as compared to those with hypovitaminosis D and secondary hyperparathyroidism. This study identifies a distinct group of patients with hypovitaminosis D and a blunted PTH response who show a disruption in calcium homeostasis but protected against PTH-mediated bone loss. This has clinical implications with respect to disease definition and may be important in deciding the optimal replacement therapy in patients with hypovitaminosis D but a blunted PTH response.     

慢性肾脏病患者维生素D缺乏与动脉僵硬度的相关性

目的 探讨慢性肾脏病患者维生素D缺乏与动脉僵硬度的相关性.方法 选取慢性肾脏病(CKD l～5期)患者300例,根据血25(OH)D3浓度分为维生素D缺乏组[25 (OH)D3＜20 μg/L]和维生素D非缺乏组[25(OH)D3≥20 μg/L].采集临床资料数据,测定动脉僵硬度指标肱踝脉搏波传导速度(baPWV).对血25(OH)D3水平与baPWV间的关系进行单因素相关分析及多元线性回归分析. 结果 维生素D缺乏组188例(62.7％),维生素D非缺乏组112例(37.3％).全部CKD患者25(OH)D3平均浓度为(17.62±8.54) μg/L,维生素D缺乏组和非缺乏组分别为(12.38±4.55) μg/L与(26.44±6.05) μg/L(P＜0.01).维生素D缺乏组baPWV值高于非缺乏组[(1 827.34±429.11) cm/s比(1 555.31±353.14) cm/s,P＜0.01].单因素相关分析显示全体CKD患者(r=-0.38,P＜0.01)以及CKD 2～5期患者[r=-0.30,P＜0.05;r=-0.26,P＜0.05;r=-0.46,P＜0.01;r=-0.57,P＜0.01]血25(OH)D3浓度与baPWV均呈负相关.多元线性回归分析显示血25 (OH)D3浓度下降与baPWV的增加独立相关(模型1:β=-0.18,P＜0.01;模型2:β=-0.17,P=0.01),回归模型1与模型2均可解释baPWV变化的50％.结论 CKD患者普遍存在维生素D缺乏,维生素D缺乏与动脉僵硬度增加相关.维生素D替代治疗可能影响CKD患者的心血管预后,但有待未来研究的进一步明确.     

Impairment of bone turnover in elderly women with hip fracture

Summary Hip fracture is one of the most severe consequences of osteoporosis affecting aged women. However, abnormalities of bone turnover responsible for bone loss in this condition have not been clearly defined. To further evaluate the bone metabolic status of women sustaining hip fracture, we have prospectively measured serum osteocalcin as a marker of bone formation and urinary excretion of pyridinoline (Pyr) and deoxypyridinoline (D-pyr) cross-links as markers of bone collagen degradation in 174 independently living women (80 ± 8 years) within a few hours after a hip fracture. Comparison was made with 77 age-matched controls (80 ± 5 years) and 17 premenopausal women (39 ± 3 years). In addition 15 of the patients were followed with daily measurements during the first postoperative week. At the time of admission osteocalcin was 20% lower in the fractured women compared to the elderly controls (7.6 ± 3.8 vs. 9.5 ± 4.5 nglml,P = 0.001). Pyr and D-pyr were 36% and 40% higher, respectively (P = 0.0001), than in elderly controls and 85% and 76% higher than in premenopausal controls (P = 0.0001). Serum osteocalcin did not correlate with the cortisol level measured at the same time (r = 0.03, ns), nor with serum albumin and creatinine. Serum osteocalcin remained unchanged within 18 hours after fracture, whereafter it progressively decreased until the third postoperative day. No correlation was noted between the excretion of pyridinoline cross-links and the time elapsed from fracture.These data suggest that the abnormal levels of osteocalcin and pyridinolines are unrelated to traumatically induced acute changes, but reflect abnormalities of bone turnover existing prior to the fracture. Thus, hip-fracture patients have biochemical evidence of decreased bone formation and increased bone resorption when compared to age-matched controls. We suggest that these abnormalities may play a role in the decrease of the bone mass and the consequently increased bone fragility that characterize the osteoporotic hip fracture in the elderly.     

The effect of a short course of calcium and vitamin d on bone turnover in older women

Calcium and vitamin D (1200 mg/day + 800 IU) has been shown to reduce hip fracture incidence in older women living in long-term care facilities who had borderline low vitamin D levels. We examined the effect of a short course of calcium and vitamin D on biochemical markers of bone turnover in older community-living women. Twelve community-living women (mean age 75 years) in good general health, without diseases or on medications known to affect bone, were entered into the study. All women were treated with calcium citrate (1500 mg/day of elemental calcium) and vitamin D₃ (1000 IU/day) (Ca + D) for 6 weeks. Biochemical markers of bone turnover were measured in serum and urine collected at baseline (two samples), 5 and 6 weeks on Ca + D, and 5 and 6 weeks after termination of Ca + D. Markers of bone formation were osteocalcin, bone alkaline phosphatase and type I procollagen peptide. Markers of bone resorption were urinary hydroxyproline, free pyridinoline and deoxypyridinoline crosslinks, and N-telopeptides of type I collagen. Parathyroid hormone (PTH) and 25-hydroxyvitamin D were also measured at baseline, 6 weeks on treatment and 6 weeks after termination of treatment. All markers of bone resorption decreased on Ca + D and returned to baseline after termination of Ca + D (p<0.05). Markers of bone formation did not change with Ca + D treatment. PTH decreased on Ca + D and returned to baseline after treatment, and 25-hydroxyvitamin D increased with treatment and remained elevated 6 weeks after the end of treatment. We conclude that Ca + D reduces bone resorption in older women, possibly by suppressing PTH levels.     

血液透析患者颈总动脉僵硬度与胰岛素抵抗的关系

目的 探讨维持性血液透析患者颈总动脉僵硬度与胰岛素抵抗的关系。 方法 选取80例非糖尿病、病情稳定的血液透析患者为研究对象。采用超声血管壁跟踪系统（Echo-tracking）在血液透析结束后1 h测定颈总动脉硬化参数β作为评价大动脉僵硬度的指标。胰岛素抵抗用内环境稳定模型评估胰岛素抵抗法（HOMA-IR）进行评价。常规检测血红蛋白、白蛋白、总胆固醇、高密度脂蛋白、低密度脂蛋白、三酰甘油、脂蛋白(a)、载脂蛋白A1、载脂蛋白B、C反应蛋白、钙、磷、肌酐。用独立样本t检验、Pearson及多元逐步回归法分析各参数关系。 结果 既往有心血管病史者颈总动脉硬化参数β大于无心血管病史者（11.41±4.13比9.75±3.63，P < 0.05）。Pearson相关分析显示，颈总动脉硬化参数β与HOMA-IR（r = 0.321，P < 0.01、年龄（r = 0.376，P < 0.01）、脉压（r = 0.267，P < 0.05）、透析龄（r = 0.219，P < 0.05）呈正相关。多元逐步回归结果显示，HOMA-IR（β = 0.228，P < 0.05）、年龄（β = 0.308，P < 0.01）是颈总动脉硬化参数β增加的独立危险因素。 结论 在血液透析患者，胰岛素抵抗可能通过参与大动脉僵硬的发生，导致心血管疾病发病率和病死率增加。     

Association of insulin resistance with arterial stiffness in nondiabetic peritoneal dialysis patients

Background  

Insulin resistance is a risk factor for cardiovascular morbidity and mortality in the general and end-stage renal disease populations. In this study, we investigated the association between insulin resistance and arterial stiffness in nondiabetic peritoneal dialysis (PD) patients.