Ovariectomy worsens secondary hyperparathyroidism in mature rats during low-Ca diet

Estrogen deficiency impairs intestinal Ca absorption and induces bone loss, but its effects on the vitamin D-endocrine system are unclear. In the present study, calciotropic hormones levels, renal vitamin D metabolism, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]-dependent intestinal calcium absorption, and bone properties in 3-mo-old sham-operated (sham) or ovariectomized (OVX) rats fed either a normal-Ca (NCD; 0.6% Ca, 0.65% P) or a low-Ca (LCD; 0.1% Ca, 0.65% P) diet for 2 wk were determined. LCD increased serum 1,25(OH)2D3 levels in both sham and OVX rats. Serum parathyroid hormone [PTH(1-84)] levels were highest in OVX rats fed LCD. Renal 25-hydroxyvitamin D1alpha-hydroxylase (1-OHase) protein expression was induced in both sham and OVX rats during LCD, while renal 1-OHase mRNA expression was highest in OVX rats fed LCD. Renal vitamin D receptor (VDR) and mRNA expressions in rats were induced by ovariectomy in rats fed NCD but suppressed by ovariectomy in rats fed LCD. The induction of intestinal calcium transporter-1 and calbindin-D9k mRNA expressions by LCD were not altered by ovariectomy. As expected, bone Ca content, cancellous bone mineral density, and bone strength index in proximal metaphysis of rat tibia were reduced by both ovariectomy and LCD (P<0.05) as analyzed by two-way ANOVA. Taken together, the data demonstrate that ovariectomy alters the responses of circulating PTH levels, renal 1-OHase mRNA expression, and renal VDR expression to LCD. These results suggest that estrogen is necessary for the full adaptive response to LCD mediated by both PTH and 1,25(OH)2D3.     

Vitamin D Binding Protein Genotype Is Associated with Serum 25-Hydroxyvitamin D and PTH Concentrations,as Well as Bone Health in Children and Adolescents in Finland

Vitamin D binding protein (DBP)/group-specific component (Gc), correlates positively with serum vitamin D metabolites, and phenotype influences serum 25-hydroxyvitamin D (S-25(OH)D) concentration. The protein isoform has been associated with decreased bone mineral density (BMD) and increased fracture risk. We examined the role of GC genotypes in S-25(OH)D status and BMD in 231 Finnish children and adolescents aged 7−19 yr. BMD was measured with DXA from lumbar spine (LS), total hip, and whole body, and for 175 subjects, radial volumetric BMD was measured with pQCT. Background characteristic and total dietary intakes of vitamin D and calcium were collected. The concentrations of 25(OH)D, parathyroid hormone (PTH), calcium and other markers of calcium homeostasis were determined from blood and urine. Genotyping was based on single-nucleotide polymorphism (rs4588) in the GC gene. The genotype distribution was: GC 1/1 68%, GC 1/2 26% and GC 2/2 6%. A significant difference emerged in 25(OH)D and PTH concentrations between the genotypes, (p = 0.001 and 0.028 respectively, ANCOVA). There was also a linear trend in: Gc 2/2 had the lowest 25(OH)D and PTH concentrations (p = 0.025 and 0.012, respectively). Total hip bone mineral content was associated with GC genotype (BMC) (p = 0.05, ANCOVA) in boys. In regression analysis, after adjusting for relevant covariates, GC genotype was associated with LS BMC and strength and strain index (SSI) Z-score in both genders, and LS BMD in boys. In conclusion, the present study demonstrates the association between GC genotypes and S-25(OH)D and PTH concentrations. The results show the influence of DBP genetic variation on bone mass accrual in adolescence.     

Osteoprotegerin--does it play a protective role in the pathogenesis of bone loss in obese perimenopausal women?

INTRODUCTION: Assessment of serum osteoprotegerin (OPG) concentrations in obese patients in comparison to healthy controls and evaluation of a possible correlation between OPG and other markers of bone turnover or calcitropic hormones. MATERIAL AND METHODS: 50 obese perimenopausal women without concomitant diseases (BMI 36.7 +/- 4.1 kg/m(2), mean age 50.4 +/- 4.9 yrs). The control group consisted of 19 healthy women (BMI 24.2 +/- 2.1 kg/m(2); mean age 53.8 +/- 5.1 yrs). In all patients serum concentration of OPG, C telopeptide of type I collagen containing the crosslinking site (CTX), osteocalcin, parathormone (PTH) and vitamin D (25-OH-D(3)) was assessed. Dual energy x-ray absorptiometry (the DXA method) of the lumbar spine and femoral neck was performed using a Lunar DPXL to measure bone marrow density (BMD). RESULTS: In obese perimenopausal women serum OPG, osteocalcin and 25-OH-D(3) levels were significantly lower, and the serum PTH level was significantly higher in comparison to healthy controls. A significantly positive correlation was found between serum OPG level and age in both obese and control subjects. CONCLUSION: The serum OPG level in obese perimenopausal women is significantly lower in comparison to healthy controls and does not correlate significantly with biochemical markers of bone turnover, calcitropic hormones and BMD. It probably cannot play a protective role in the pathogenesis of bone loss in obese perimenopausal women.     

1alpha,25(OH)2D3 and parathyroid hormone (PTH) signaling in rat intestinal cells: activation of cytosolic PLA2

In the current study, we have probed the role of cytosolic phospholipase A2 (cPLA2) activity in the cellular response to the calciotropic hormones, 1alpha,25,dihydroxy-vitamin D(3) [1alpha,25(OH)(2)D(3)] and PTH. Stimulation of rat enterocytes with either hormone, increased release of arachidonic acid (AA) 3H-AA] one-two fold in a concentration and time-dependent manner. The effect of either hormone on enterocytes was totally reduced by preincubation with the intracellular Ca(2+) chelator BAPTA-AM (5 microM), suggesting that the release of AA following cell exposure to the calciotropic hormones occurs mainly through a Ca(2+)-dependent mechanism involving activation of Ca(2+)-dependent cPLA2. Calciotropic homone stimulation of rat intestinal cells increases cPLA2 phosphorylation (three to four fold). This effect was decreased by PD 98059 (20 microM), a MAP kinase inhibitor, indicating that this action is, in part, mediated through activation of the MAP kinases ERK 1 and ERK2. Enterocytes exposure to 1alpha,25(OH)(2)D(3) (1nM) or PTH (10 nM) also resulted in P-cPLA2 translocation from cytosol to nuclei and membrane fractions, where phospholipase subtrates reside. Collectively, these data suggest that PTH and 1alpha,25(OH)(2)D(3) activate in duodenal cells, a Ca(2+)-dependent cytosolic PLA2 and attendant arachidonic acid release and that this activation requieres prior stimulation of intracellular ERK1/2. 1alpha,25(OH)(2)D(3) and PTH modulation of cPLA2 activity may change membrane fluidity and permeability and thereby affecting intestinal cell membrane function.     

Decreased fractional urinary calcium excretion and serum 1,25-dihydroxyvitamin D and IGF-I levels in preeclampsia

During preeclampsia several alterations of calcium metabolism have been described, the most common of them is hypocalciuria, which pathophysiology is still unclear. In order to assess the contribution of calciotropic hormones to urinary calcium excretion, a cross-sectional study was done including 26 preeclamptic Mexican women (PE group) and 26 normotensive control pregnant women (NT group). Total and fractional urinary calcium excretion were significantly lower (P<0.0001) in the PE group than in the NT group (82+/-7 versus 171+/-7 mg/24h and 0.62+/-0.38 versus 1.38+/-0.71%, respectively), without significant differences in creatinine clearance, urinary sodium excretion and phosphate tubular reabsorption. In addition, serum 1,25-(OH)(2)D and IGF-I levels were significantly (P<0.05) lower in the PE than in NT group (43+/-9 versus 50+/-9 pg/mL and 195+/-67 versus 293+/-105 ng/mL, respectively), without significant differences in serum PTH levels. In the NT group, association analysis showed that total and fractional urinary calcium excretions positively correlated with serum levels of 1,25-(OH)(2)D (P<0.01) and IGF-I (P<0.001). In the PE group, total urinary calcium excretion positively correlated only with serum 1,25-(OH)(2)D (P<0.05). In conclusion, the results obtained in this study confirm that PE is associated with hypocalciuria and suggest that 1,25-(OH)(2)D and/or IGF-I may be involved in the regulation of urinary calcium excretion.     

Quantitative genetics of circulating molecules associated with bone metabolism: a review

This paper reviews recent advances in the studies of various biochemical factors (biomarkers) involved in bone metabolism and remodeling. The collected data in this area suggest the existence of complex and multilevel relationships between calciotropic hormones, various cytokines and growth factors. The paper summarizes the data on the magnitude of the familial and genetic effects on the interindividual variation in circulating levels of many of these biomarkers. The majority of the cited heritability estimates are well above 20%, reaching up to 80% for some cytokines (e.g., TNFalpha and VEGF). These estimates point to potential targets for the identification of novel quantitative trait loci involved in the control of the respective molecules variation. This information is of particular importance, because the available data on the association between specific genes/polymorphisms and the respective circulating molecules variation is still very limited. The paper also provides recent findings on the genetics of co-variation between the circulating levels of various biomarkers. It shows that only in a few instances, such as for example, between IGF-I and IGFBP-3, and IGFBP-1 and leptin, significant and substantial genetic (and environmental) correlations were found. It appears that despite the prominent strong genetic effects on variation of each of the numerous biomarkers, the pleiotropic effects are rather limited. We consider briefly some important new data obtained using the gene expression approach and microarray technique. The data, for instance, indicate that the genetic effects on bone metabolism appear to be an open system, which can be activated or modulated by external factors such as drugs, e.g., PTH. Extensive molecular genetic studies in this area are both timely and imperative to detect the specific genes affecting variation (and co-variation) of the circulating factors associated with bone metabolism.     

Seasonal variation and correlation analysis of vitamin D and parathyroid hormone in Hangzhou,Southeast China

This study aimed to describe the 25‐hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) status of Southeast Chinese individuals influenced by season. The secondary aim was to determine the cutoff for sufficient 25(OH)D in a four‐season region. From January 2011 to June 2014, a total of 17 646 individuals were evaluated in our study. The serum levels of PTH were detected simultaneously in 5579 cases. A total of 25(OH)D and intact PTH were measured by the electrochemiluminescent immunoassay. The distribution of the concentration, prevalence and seasonal variability of 25(OH)D and PTH were studied. The mean 25(OH)D concentration in our study was 43.00(30.40) nmol/L. The prevalence of insufficiency (25(OH)D < 50 nmol/L) was 62.87% and that of deficiency (<30 nmol/L) was 28.54%. Mean serum 25(OH)D levels revealed a limited sinusoidal profile throughout the year and were significantly higher in Autumn. On the other hand, PTH levels showed an opposite response to seasonal effects relative to 25(OH)D. Age, BMI and daylight were not significantly correlated with 25(OH)D and serum PTH reached a plateau at higher values of serum 25(OH)D of 42.86 nmol/L. This study demonstrated that Vitamin D insufficiency is highly prevalent in Southeast China. The concentration of 25(OH)D in the male group was generally higher than that in the female group. Seasonal variation was an important aspect of 25(OH)D and PTH concentration. This study revealed that the optimal serum threshold of 25(OH)D for bone health should be between 40 and 50 nmol/L for Southeast Chinese individuals.     

Abnormalities of Vitamin D and Calcium Metabolism after Surgical Treatment of Morbid Obesity: A Study of 136 Patients

ObjectiveTo assess the effect of bariatric surgical treatment of morbid obesity on bone mineral metabolism.MethodsWe analyzed pertinent vitamin D and calcium metabolic variables in 136 patients who had undergone a malabsorptive bariatric operation. Measurements of bone mineral density (BMD), serum 25-hydroxyvitamin D (25-OHD), 1,25-dihydroxyvitamin D [1,25-(OH)₂D], parathyroid hormone (PTH), calcium, phosphorus, and alkaline phosphatase were performed. Statistical analyses assessed correlations among various factors.ResultsThe mean age (± SD) of the study group was 48.34 ± 10.28 years. Their mean weight loss was 114.55 ± 45.66 lb, and the mean duration since the bariatric surgical procedure was 54.02 ± 51.88 months. Seventeen patients (12.5%) had a T-score of -2.5 or less, and 54 patients (39.7%) had a T-score between –1.0 and –2.5. Of 119 patients in whom serum 25-OHD was measured, 40 (34%) had severe hypovitaminosis D (25-OHD < 8 ng/mL), and 50 patients (42%) had low hypovitaminosis D (serum 25-OHD 8 to 20 ng/mL). The magnitude of weight loss correlated negatively with serum 25-OHD, calcium, phosphorus, and calcium × phosphorus product values and positively with serum alkaline phosphatase level. Serum 25-OHD and calcium concentrations correlated positively with the BMD. PTH, serum 1,25-(OH)₂D, and alkaline phosphatase concentrations correlated negatively with the BMD, a reflection of the presence of secondary hyperparathyroidism, an accelerated conversion of 25-OHD to 1,25-(OH)₂D by the elevated PTH levels, and increased osteoblastic activity. The mean daily vitamin D supplementation was 6,472 ± 9,736 IU.ConclusionHypovitaminosis D and subsequent bone loss are common in patients who have undergone a bariatric surgical procedure for morbid obesity. These patients require rigorous vitamin D supplementation. (Endocr Pract. 2007;13:131-136)     

Effects of vitamin K2 administration on calcium balance and bone mass in young rats fed normal or low calcium diet

OBJECTIVE: The purpose of this study was to examine the effects of vitamin K2 administration on calcium balance and bone mass in young rats fed a normal or low calcium diet. METHODS: Forty female Sprague-Dawley rats, 6 weeks of age, were randomized by stratified weight method into four groups with 10 rats in each group: 0.5% (normal) calcium diet, 0.1% (low) calcium diet, 0.5% calcium diet + vitamin K2 (menatetrenone, 30 mg/100 g chow diet), and 0.1% calcium diet + vitamin K2. After 10 weeks of feeding, serum calcium and calciotropic hormone levels were measured, and intestinal calcium absorption and renal calcium reabsorption were evaluated. Bone histomorphometric analyses were performed on cortical bone of the tibial shaft and cancellous bone of the proximal tibia. RESULTS: Feeding a low calcium diet induced hypocalcemia, increased serum parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D [1,25(OH)2D] levels with decreased serum 25-hydrovyvitamin D [25(OH)D] level, stimulated intestinal calcium absorption and renal calcium reabsorption, and reduced cortical bone mass as a result of decreased periosteal bone gain and enlarged marrow cavity, but did not significantly influence cancellous bone mass. Vitamin K2 administration in rats fed a low calcium diet stimulated renal calcium reabsorption, retarded the abnormal elevation of serum PTH level, increased cancellous bone mass, and retarded cortical bone loss, while vitamin K2 administration in rats fed a normal calcium diet stimulated intestinal calcium absorption by increasing serum 1,25(OH)2D level, and increased cortical bone mass. CONCLUSION: This study clearly shows the differential response of calcium balance and bone mass to vitamin K2 administration in rats fed a normal or low calcium diet.     

老年男性血清脂联素与骨密度的关系

目的：研究老年男性血清脂联素与骨密度和骨转化指标之间的关系。方法：对165例男性老年患者采用双能量X线吸收测量仪测定骨密度、肌肉及脂肪量,同时测定患者血清脂联素、骨碱性磷酸酶、甲状旁腺素、25羟维生素D和I型胶原β羧基端肽水平。结果：165例年龄超过58岁男性患者（平均年龄69.4±6.4岁,体重指数24.9±3.1 kg/m2）,脂联素与股骨颈骨密度相关系数为-0.31（P〈0.05）、与全髋骨密度相关系数为-0.23（P〈0.05）,年龄、BMI和脂肪量校正后,脂联素仅与股骨颈骨密度有显著相关（r=-0.25,P〈0.05）;脂联素与骨碱性磷酸酶正相关（r=0.28,P〈0.01）,混杂因素校正后,相关仍具有显著性（r=0.19,P〈0.05）;脂联素与I型胶原β羧基端肽呈正相关（r=0.15,P〈0.05）。结论：老年男性血清脂联素与股骨颈骨密度和骨ALP密切相关。     

Increased PTH and 1.25(OH)(2)D levels associated with increased markers of bone turnover following bariatric surgery

The objective of this study was to characterize changes in metabolic bone parameters following bariatric surgery. Seventy-three obese adult patients who underwent either gastric banding (GB), Roux-en-Y gastric bypass (RYGB), or biliopancreatic diversion with duodenal switch (BPD/DS) were followed prospectively for 18 months postoperatively. Changes in the calcium-vitamin D axis (25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D (1,25(OH)(2)D), calcium, parathyroid hormone (PTH)), markers of bone formation (osteocalcin, bone-specific alkaline phosphatase) and resorption (urinary N-telopeptide (NTx)), as well as bone mineral density (BMD) were assessed at 3-month intervals during this time period. Bariatric surgery resulted in significant and progressive weight loss over 18 months. With supplementation, 25OHD levels increased 65.3% (P < 0.0001) by 3 months, but leveled off and decreased <30 ng/ml by 18 months. PTH initially decreased 21.4% (P = 0.01) at 3 months, but later approached presurgery levels. 1,25(OH)(2)D increased significantly starting at month 12 (50.3% increase from baseline, P = 0.008), and was positively associated with PTH (r = 0.82, P = 0.0001). When stratified by surgery type, median PTH and 1,25(OH)(2)D levels were higher following combined restrictive and malabsorptive operations (RYGB and BPD/DS) compared to GB. Bone formation/resorption markers were increased by 3 months (P < 0.05) and remained elevated through 18 months. Radial BMD decreased 3.5% by month 18, but this change was not significant (P = 0.23). Our findings show that after transient improvement, preoperative vitamin D insufficiency and secondary hyperparathyroidism persisted following surgery despite supplementation. Postoperative secondary hyperparathyroidism was associated with increased 1,25(OH)(2)D levels and increased bone turnover markers.     

High Prevalence of Vitamin D Insufficiency in China: Relationship with the Levels of Parathyroid Hormone and Markers of Bone Turnover

There is a lack of large-scale studies on vitamin D status and its relationship to parathyroid hormone (PTH) and bone turnover markers in adults living in Shanghai. The objectives were to determine the prevalence of vitamin D insufficiency in Shanghai and to investigate the relationship of 25(OH)D with parathyroid function and bone turnover markers. This cross-sectional study involved 649 men and 1939 women aged 20–89 years who were randomly sampled in Shanghai. Serum concentrations of 25(OH)D, PTH, albumin, and bone turnover markers were measured. During the winter season, the prevalence of vitamin D insufficiency (<30 ng/mL) was 84% in males and 89% in females. The prevalence of vitamin D deficiency (<20 ng/mL) was 30% in males and 46% in females. With increasing serum 25(OH)D concentrations categorized as <10, 10–20, 20–30, and ≥30 ng/mL, the mean PTH and bone turnover markers levels gradually decreasd in both sexes (p<0.001). There was an inverse relationship between the serum 25(OH)D and PTH concentrations in both genders, but no threshold of 25(OH)D at which PTH levels plateaued was observed. There were modest but significantly inverse relationships between the levels of 25(OH)D and bone turnover markers, but no plateau was observed for serum 25(OH)D levels up to 40 ng/mL.     

Decreased levels of ionized calcium one year after hemithyroidectomy: importance of reduced thyroid hormones

BACKGROUND: Previously we have found reduced levels of total serum calcium and 1,25(OH)2D3 despite an unaltered stimulated parathyroid hormone (PTH) secretion 1 year after hemithyroidectomy. The present study was undertaken to elucidate the possible relationship between calcium homeostasis, thyroid hormones and bone resorption in a group of 45 consecutive patients subjected to hemithyroidectomy because of a solitary nodule. All patients had free T4 and T3 levels within normal range preoperatively. METHODS: Thyroid hormones, bone mineral and biochemical variables known to reflect calcium homeostasis were studied. Patients were divided into three separate groups depending on their pre- and postoperative thyroid hormone status. RESULTS: One year postoperatively, serum levels of free T4 were decreased and that of thyrotropin (TSH) increased in the entire group of patients. The concentration of ionized calcium was reduced from 1.25 +/- 0.05 to 1.22 +/- 0.04 (p < 0.001) despite an unaltered PTH value (2.8 +/- 1.0 vs. 3.1 +/- 1.5, p = 0.50). A significant reduction in C-terminal telopeptide type 1 collagen (1CTP) indicated decreased bone resorption 1 year after surgery (p < 0.05). Subgroup analysis showed that a reduction in ionized calcium was seen only among patients with a postoperative decrease in free T4. Patients with subclinical hyperthyroidism preoperatively presented the lowest postoperative levels of ionized calcium, significantly reduced levels of 1CTP and increased levels of phosphate and creatinine. Multiple linear regression analysis showed that age (p < 0.05) and postoperatively changed serum levels of TSH (p < 0.05), creatinine (p < 0.05), phosphate (p < 0.001) and FT4 (p < 0.01) were independently associated with altered levels of ionized calcium. CONCLUSION: We conclude that the reduction in ionized calcium 1 year after hemithyroidectomy was not due to PTH deficiency. Instead our results suggest that the reduced effects of thyroid hormones on bone and kidney function is essential.     

1,25-Dihydroxyvitamin D and the Vitamin D Receptor Gene Polymorphism Apa1 Influence Bone Mineral Density in Primary Hyperparathyroidism

Objective

Parathyroid hormone (PTH) and vitamin D are the most important hormones regulating calcium metabolism. In primary hyperparathyroidism (PHPT) excessive amounts of PTH are produced. Bone turnover is enhanced, leading to reduced bone mineral density and elevated levels of serum calcium. The aim of this study was to investigate relations between serum levels of 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)₂D) and bone mineral density, as well as known genetic polymorphisms in the vitamin D receptor and enzymes metabolising vitamin D in patients with PHPT.

Design/Subjects

We conducted a cross-sectional study of 52 patients with PHPT.

Results

Mean level of 25(OH)D was 58.2 nmol/L and median 1,25(OH)₂D level was 157 pmol/L. Among our patients with PHPT 36.5% had 25(OH)D levels below 50 nmol/L. Serum 1,25(OH)₂D was inversely correlated to bone mineral density in distal radius (p = 0.002), but not to bone mineral density at lumbar spine or femoral neck. The vitamin D receptor polymorphism Apa1 (rs7975232) was associated with bone mineral density in the lumbar spine.

Conclusions

The results suggest that PHPT patients with high blood concentrations of 1,25(OH)₂D may have the most deleterious skeletal effects. Randomized, prospective studies are necessary to elucidate whether vitamin D supplementation additionally increases serum 1,25(OH)₂D and possibly enhances the adverse effects on the skeleton in patients with PHPT.     

Serum osteocalcin levels do not change during rapidly induced hypercalcemia in healthy subjects.

Since osteocalcin has been suggested to play a role in calcium homeostasis, we investigated its serum levels in 6 healthy subjects during a rapid calcium infusion. Serum levels of intact parathyroid hormone (PTH), 25-hydroxyvitamin D [25-(OH) D3] and 1,25-dihydroxyvitamin D [1,25-(OH)2 D3] were also determined. The calcium infusion increased plasma-ionized calcium levels from 1.25 +/- 0.04 to 1.54 +/- 0.07 mmol/l at 30 min (p less than 0.05). Concomitantly, serum levels of intact PTH declined from 2.1 +/- 0.9 to 0.2 +/- 0.3 mmol/l (p less than 0.05). In contrast, serum osteocalcin levels did not change. Further, during calcium infusion, serum levels of 1,25-(OH)2 D3 decreased from 81 +/- 17 to 75 +/- 15 pmol/l (p less than 0.05) whereas serum levels of 25-(OH) D3 did not change. The results therefore suggest that calcium per se does not influence osteocalcin secretion.     

Administration of parathyroid hormone, prostaglandin E2, or 1-alpha,25-dihydroxyvitamin D3 restores the bone inductive activity of rhBMP-2 in aged rats

Bone morphogenetic protein (BMP) induces bone formation in young rodents, but aging causes a reduction in the bone-forming ability of BMP. Most patients who require bone reconstruction are relatively old. Accordingly, we examined whether anabolic hormones could restore the bone inductive activity of rhBMP-2 in aged rats. rhBMP-2 in a carrier pellet was implanted subcutaneously in both 4- and 50-week-old female Wistar rats. PTH, PGE2, or 1,25(OH)2D3 was injected every day during the period of BMP implantation. The pellets were harvested, and were examined both histologically and biochemically 2 weeks after implantation. Bone-forming ability was measured by alkaline phosphatase (ALP) activity and calcium (Ca) content. Pellets in 50-week-old rats showed a significant reduction in bone formation compared to pellets in 4-week-old rats. However, daily injections of PTH into 50-week-old rats restored both ALP activity (103 +/- 4.6%) and Ca content (105 +/- 2.6%). 1,25(OH)2D3 and PGE2 also restored Ca content (103 +/- 4.5% and 98 +/- 3.8%, respectively) and stimulated ALP activity (142 +/- 2.3% and 133 +/- 3.6%). These results show that the administration of these hormones restores bone-forming ability in aged rats. A combination treatment of these hormones with rhBMP-2 might be applicable to the reconstruction of bone defects in elderly patients.     

Vitamin d status and its relationship with bone mineral density and parathyroid hormone in southeast asian adults with low bone density

ObjectiveTo investigate the vitamin D sufficiency status and the relationships among serum 25-hydroxyvitamin D [25(OH)D] levels, intact parathyroid hormone (iPTH) levels, and bone mineral density (BMD) in patients attending an osteoporosis clinic in Singapore.MethodsIn total, 193 adults with or without prevalent fragility fractures and with low BMD at the femoral neck, total hip, or lumbar spine underwent assessment. Multivariate regression models were used to investigate the relationships among serum 25(OH)D, iPTH, and BMD.ResultsThe mean values (standard deviation) for age of the patients and serum 25(OH)D level were 61 (14) years and 26.05 (7.97) ng/mL, respectively. In 72% of patients, serum 25(OH)D levels were below 30 ng/mL. There was no association between 25(OH)D levels and BMD at the femoral neck, total hip, or lumbar spine(P = .568, .461, and .312, respectively). Serum iPTH levels were negatively associated with BMD at the total hip(P = .035) and the lumbar spine (P = .019). At levels < 30 ng/mL, 25(OH)D was negatively associated with iPTH (P = .036).ConclusionAmong this Southeast Asian population of patients with low BMD, no direct relationship between serum 25(OH)D levels and BMD was observed. A negative correlation existed, however, between iPTH and 25(OH)D at serum 25(OH)D concentrations < 30 ng/mL, and serum iPTH levels showed a significant negative association with BMD at the total hip and lumbar spine. These significant negative associations between iPTH levels and BMD at the total hip and lumbar spine underscore the critical role of this hormone in bone metabolism and health. (Endocr Pract. 2011;17:226-234)     

Vitamin D status and its relation to age and body mass index

BACKGROUND/AIMS: While numerous studies have examined 25(OH)-vitamin D(3) (25-D) concentrations and their relation to parathyroid hormone (PTH) levels there is only limited information on the interrelation between 25-D, 1,25(OH)(2)-vitamin D(3) (1,25-D) and PTH. It was the aim of this study to assess the vitamin D endocrine system and its relation to age and body mass index (BMI). METHODS: This cross-sectional study comprised a convenience sample of 483 adults which attended the endocrinology outpatient service of a university hospital in the years 2002-2004. RESULTS: The mean concentrations of 25-D, 1,25-D, calcium and PTH were 21.0 +/- 10.6 ng/ml, 47.9 +/- 21.7 pg/ml, 9.48 +/- 0.48 mg/dl and 51.0 +/- 27.2 pg/ml, respectively. 25-D was related (p < 0.01) to BMI, age, PTH and 1,25-D. After correction for 25-D, we found no relation between BMI and 1,25-D. PTH was related (p < 0.01) to serum calcium, BMI, age and 1,25-D (p = 0015). There was a seasonal variation in both, 25-D and 1,25-D serum concentrations: 25-D levels were lowest in January and increased until July while the nadir and zenith of 1,25-D were found in April and October, respectively. CONCLUSION: Since BMI was negatively related to 25-D the prevalence of 25-D deficiency (<8.8 ng/ml) increased from 8.8% in subjects with BMI <30 kg/m(2) to 15.0% in subjects with BMI >30 kg/m(2). BMI, age and season should be taken into account when assessing a patients vitamin D status and more aggressive vitamin D supplementation should be considered for obese subjects.     

Effect of cervus and cucumis polypeptide combined with zoledronic acid on bone metabolic biochemical markers in glucocorticoids – Induced osteoporosis patients

ObjectiveTo investigate the effect of cervus and cucumis polypeptide combined with zoledronic acid on bone metabolic biochemical markers in glucocorticoids - induced osteoporosis patients.MethodsA total of 100 patients with glucocorticoids - induced osteoporosis admitted to our hospital from January 2015 to June 2017 were enrolled in this study. Patients were divided into observation group and control group by random number table method, 50 cases in each group. Patients in the observation group were treated with deer melon polypeptide in combination with zoledronic acid, and patients in the control group were treated with zoledronic acid alone. The patients in both groups were treated for 2 months. The changes of bone mineral density (BMD) and biochemical markers of bone metabolism in lumbar vertebrae L1-4, left femoral neck and large trochanter were analyzed before and after treatment.ResultsThe pre- BMD at lumbar spine L_1-4, left femoral neck and great trochanter had no statistic difference (P > 0.05), the BMD at each sites improved after treatment, and the difference were statistical before and after treatment (P < 0.05). BMD at above sites of two groups after treatment had statistical difference (P < 0.05), and the BMD at lumbar spine L_1-4, left femoral neck and great trochanter in the observation group was higher than that of the control group. There were no significant differences in PTH, 25-(OH)D3, TRACP, β-CTX and BGP levels between the two groups before treatment (P > 0.05). The levels of 25-(OH)D3, TRACP, β-CTX and BGP in the two groups were significantly improved after treatment (P < 0.05), and the levels of PTH, TRACP and β-CTX in the observation group were significantly lower than those in the control group. The levels of 25-(OH) D3 and BGP were significantly higher than those of the control group (P < 0.05).ConclusionThe cervus and cucumis polypeptide combined with zoledronic acid can improve the BMD at lumbar spine L_1-4, left femoral neck and great trochanter, and ameliorate the bone metabolic biochemical markers for patients with glucocorticoids - induced osteoporosis.