Regulation of PTH secretion by 25-hydroxyvitamin D and ionized calcium depends on vitamin D status: A study in a large cohort of healthy subjects

IntroductionPrevious papers investigating vitamin D status have often outlined the significant relationships between serum parathyroid hormone (PTH) and 25-hydroxyvitamin D (25OHD), but the influence of ionized calcium levels has not been concomitantly considered.DesignCross-sectional.Materials and methodsIn 1050 healthy men (547) and women (503), serum ionized calcium (iCa), creatinine (Cr), albumin, 25OHD, and PTH were measured. After conventional analysis, a regression tree was fitted on the data set.Results25OHD and PTH values showed significant opposite seasonal changes. 25OHD levels negatively correlated with PTH, which in turn negatively correlated with iCa. A regression tree was fitted to the whole data set using PTH as the response variable and 25OHD and iCa as covariates. PTH concentration depended on that of iCa only in subjects with 25OHD levels > 16.35 ng/mL, while for 25OHD <16.35 ng/mL it depended on 25OHD values.ConclusionsOur results indicated that PTH levels were highly conditioned by those of 25OHD in subjects with 25OHD values lower than 16.35 ng/mL and by those of iCa only for higher 25OHD concentration.     

Vitamin D deficiency in northern Vietnam: Prevalence,risk factors and associations with bone mineral density

PurposeVitamin D deficiency has been linked to osteoporosis and also to the risk of cancer, autoimmune disorders and cardiovascular diseases. This study sought to determine the prevalence of, and risk factors for, vitamin D deficiency and its relationship with bone mineral density (BMD) in a Vietnamese population.MethodsThis cross-sectional study involved 269 women and 222 men aged 13–83 years, who were randomly selected from urban and rural areas in northern Vietnam. Serum concentrations of 25-hydroxy-vitamin D [25(OH)D] and parathyroid hormone (PTH) were measured by electrochemiluminescence immunoassay. Vitamin D deficiency was defined as serum 25(OH)D levels below 20 ng/mL. BMD was measured by dual X-ray absorptiometry.ResultsThe prevalence of vitamin D deficiency in women was 30%, almost two-fold higher than in men (16%). Significant predictors of vitamin D deficiency in women were urban residency (p < 0.01) and age less than 30 years (p < 0.01), whereas use of contraceptive pills was protective (p < 0.01). In men, winter season was the only significant predictor of vitamin D deficiency (p < 0.01). In multiple linear regression analysis, serum levels of 25(OH)D were positively associated with BMD in both women (p < 0.001) and men (p < 0.001).ConclusionsThese data suggest that the prevalence of vitamin D deficiency is high in the Vietnamese population, and that part of this prevalence could be explained by low exposure to sunlight (urban residency and winter season). The high prevalence of vitamin D deficiency should raise the awareness of potentially important health issues such as osteoporosis within the Vietnamese society.     

Vitamin D deficiency in northern Vietnam: Prevalence,risk factors and associations with bone mineral density

PurposeVitamin D deficiency has been linked to osteoporosis and also to the risk of cancer, autoimmune disorders and cardiovascular diseases. This study sought to determine the prevalence of, and risk factors for, vitamin D deficiency and its relationship with bone mineral density (BMD) in a Vietnamese population.MethodsThis cross-sectional study involved 269 women and 222 men aged 13–83 years, who were randomly selected from urban and rural areas in northern Vietnam. Serum concentrations of 25-hydroxy-vitamin D [25(OH)D] and parathyroid hormone (PTH) were measured by electrochemiluminescence immunoassay. Vitamin D deficiency was defined as serum 25(OH)D levels below 20 ng/mL. BMD was measured by dual X-ray absorptiometry.ResultsThe prevalence of vitamin D deficiency in women was 30%, almost two-fold higher than in men (16%). Significant predictors of vitamin D deficiency in women were urban residency (p < 0.01) and age less than 30 years (p < 0.01), whereas use of contraceptive pills was protective (p < 0.01). In men, winter season was the only significant predictor of vitamin D deficiency (p < 0.01). In multiple linear regression analysis, serum levels of 25(OH)D were positively associated with BMD in both women (p < 0.001) and men (p < 0.001).ConclusionsThese data suggest that the prevalence of vitamin D deficiency is high in the Vietnamese population, and that part of this prevalence could be explained by low exposure to sunlight (urban residency and winter season). The high prevalence of vitamin D deficiency should raise the awareness of potentially important health issues such as osteoporosis within the Vietnamese society.     

Strong relationship between vitamin D status and bone mineral density in anorexia nervosa

BackgroundAnorexia nervosa (AN) is associated with impaired bone health and low bone mineral density (BMD) as a consequence of an inadequate peak bone mass in adolescence and bone loss in young adulthood. The vitamin D status with its implications for bone health in patients affected by AN has only been examined previously in small studies.ObjectiveTo evaluate the prevalence of vitamin D deficiency and test the hypothesis that patients with AN and vitamin D deficiency might have worse bone metabolism and lower bone density as compared with AN with adequate vitamin D repletion.DesignWe analysed the vitamin D status and bone metabolism in a large cohort (n = 89) of untreated patients affected by AN, with amenorrhoea.ResultsVitamin D deficiency is widespread in untreated patients with AN: 16.9% had 25OH vitamin D levels below 12 ng/ml, 36% below 20 ng/ml and 58.4% below 30 ng/ml. PTH values were higher and BMD at both femoral sites were lower in patients with vitamin D < 20 ng/ml. Progressively higher values of BMD were observed by 4 ranks of 25 OH vitamin D values (severe deficiency: < 12 ng/ml, deficiency: ≥ 12 ng/ml and < 20 ng/ml, insufficiency: ≥ 20 and < 30 ng/ml and normal: ≥ 30 ng/ml). In patients with severe vitamin D deficiency BMD at the hip were significantly lower than that measured in groups with values over 20 ng/ml (p < 0.001 for trend). The level of significance did not change for values adjusted for BMI or body weight.ConclusionWe found a strong relationship between vitamin D status and hip BMD values with additional benefits for those with 25OHD levels above 20 ng/ml. Our results support the design of a randomized placebo-controlled clinical trial on the effect of vitamin D on BMD in patients with AN. The second point, whether 25OHD should be above 20 or 30 ng/ml remains a discussion point.     

Vitamin D metabolites and bone mineral density: The multi-ethnic study of atherosclerosis

Previous studies demonstrate associations of low 25-hydroxyvitamin D (25(OH)D) concentrations with low bone mineral density (BMD) and fractures, motivating widespread use of vitamin D supplements for bone health. However, previous studies have been limited to predominantly White populations despite differences in the distribution and metabolism of 25(OH)D by race/ethnicity. We determined associations of serum 25(OH)D, 24,25-dihydroxyvitamin D (24,25(OH₂)D₃), and parathyroid hormone (PTH) with BMD among 1773 adult participants in the Multi-Ethnic Study of Atherosclerosis (MESA) in a staggered cross-sectional study design. Vitamin D metabolites were measured using liquid chromatography-mass spectroscopy and PTH using a 2-site immunoassay from serum collected in 2000–2002. Volumetric trabecular lumbar BMD was measured from computed tomography scans performed in 2002–2005 expressed as g/cm³. We used linear regression and graphical methods to compare associations of vitamin D metabolite and PTH concentrations with BMD as the outcomes measure among White (n = 714), Black (n = 353), Chinese (n = 249), and Hispanic (n = 457) participants. Serum 25(OH)D and 24,25(OH₂)D₃ concentrations were highest among Whites and lowest among Blacks. BMD was greatest among Black participants. Higher serum 25(OH)D was only associated with higher BMD among Whites and Chinese participants (P-for-interaction = 0.054). Comparing the lowest category of 25(OH)D (< 20 ng/ml) to the highest (≥ 30 ng/ml), the adjusted mean difference in BMD was –8.1 g/cm³ (95% CI − 14.8, − 1.4) for Whites; − 10.2 g/cm³ (− 20.4, 0.0) for Chinese vs. 8.8 g/cm³ (− 2.8, 20.5) for Black and − 1.1 g/cm³ (− 8.3, 6.2) for Hispanic. Similar results were observed for serum 24,25(OH₂)D_3. Serum PTH was not associated with BMD. In a multi-ethnic population, associations of 25(OH)D with BMD were strongest among White and Chinese participants and null among Black and Hispanic participants. Further studies are needed to determine optimal biomarkers for bone health for multiple ethnic groups.     

Functional hypoparathyroidism in postmenopausal women with fragility fracture

IntroductionSecondary hyperparathyroidism sometimes is lacking despite authentic vitamin D insufficiency (VDI) and the concept of functional hypoparathyroidism with a protective role on bone status has been proposed. Therefore, we tested the hypothesis that its prevalence was very low in a population of women with a peripheral fragility fracture.MethodsWe conducted our study in postmenopausal women, admitted for such a fracture in our Fracture Liaison Service. All had bone mineral density (BMD), biochemical assessment and a medical visit.ResultsTwo hundred and thirty seven women (72.9 ± 11.6-year-old) were included and 90.4% had VDI (25[OH]D ≤ 30 ng/mL). Yet, 87.9% of the latter had normal PTH levels less or equal to 64 ng/L. In this population with VDI (n = 214), we found no PTH plateau level related to 25(OH)D. Since a recent study reported an increase in the risk of fracture only when 25(OH)D was below 15 ng/mL, we then used this value as a new threshold. We observed a significant difference in hip BMD between patients with 25(OH)D either less or equal to or greater than 15 ng/mL. However, 81.2% of the formers were still with normal PTH with no difference in BMD whether PTH level was above or within normal range.ConclusionIn a population of postmenopausal women with a fragility fracture, we found that 25(OH)D less or equal to 15 ng/mL was associated with significantly lower hip BMD. Even using this low threshold, we found a high prevalence of functional hypoparathyroidism and it was not associated with any difference in hip or spine BMD. Overall, our results do not support the hypothesis of a protective effect of this biological profile.     

Relationship between vitamin D deficiency and bone fragility in sickle cell disease: A cohort study of 56 adults

BackgroundRecent studies suggest that patients with sickle cell disease (SCD) have profound vitamin D (VD) deficiency. Limited data exist on the effect of VD deficiency on bone fragility in these patients.ObjectivesTo assess the prevalence of VD deficiency in adults with SCD and its consequences on bone metabolism and fragility.MethodsThis prospective study included 56 SCD adult patients (mean age 29.8 ± 9.5 years), in a clinically steady state. Clinical and laboratory data were recorded. Bone mineral density (BMD) was measured using dual X-ray absorptiometry. Fracture history, BMD, avascular osteonecrosis, H-shaped vertebra and markers of mineral metabolism were compared between two groups of patients presenting very low (≤ 6 ng/mL, n = 26) (group 1) and low (> 6 ng/mL, n = 26) (group 2) 25(OH)D concentration, respectively.ResultsMedian 25(OH)D concentration was 6 ng/mL. VD deficiency (25(OH)D < 10 ng/mL) was found in 42 out of 56 patients (75%) and secondary hyperparathyroidism in 40 (71.4%). History of fracture was documented in 17 patients (30.3%), osteopenia and/or osteoporosis in 39.6% of patients. Overall, patients of group 1 were more likely to have sustained a fracture (42.8%) compared to patients of group 2 (17.8%) (p = 0.04). These patients had also lower body mass index and significantly higher parathyroid hormone, C-terminal telopeptides of type I-collagen and bone-specific alkaline phosphatase serum levels. There was no difference between group for BMD, avascular osteonecrosis history, H-shaped vertebra, and disease severity markers.ConclusionThis study suggests that VD deficiency is a key feature in SCD-bone disease. It is highly prevalent and associated with hyperparathyroidism, bone resorption markers, and history of fracture. The optimal supplementation regimen remains to be determined.     

Seasonal changes in serum calcium,PTH and vitamin D levels in patients with primary hyperparathyroidism

BackgroundSeasonal variations of 25-hydroxyvitamin D, PTH and calcium levels are not well characterized in primary hyperparathyroidism (PHPT). Our objectives were to characterize seasonal changes in these parameters in PHPT patients, and to assess whether these seasonal changes affect clinical decision making.MethodsThis is a retrospective study based on the electronic medical records of Clalit Health service in the south of Israel between 2000 and 2012. Patients 18 years and older with PHPT (PTH > upper limit of norm (ULN) and serum calcium > 10.5 mg%) were included. Patients with renal failure or on Thiazide diuretics were excluded. All serum levels of calcium, PTH and 25-hydroxyvitamin D were collected and then stratified according to season.Results792 patients were classified as PHPT (72.2% female) and had a total of 2659 PTH tests, 1395 25-hydroxyvitamin D tests and 7426 calcium test. Fifty six percent of 25-hydroxyvitamin D levels were < 50 nmol/L. Seasonality was demonstrated in all three parameters: mean 25-hydroxyvitamin D was 13% higher in the summer compared to the winter (P < 0.001), median PTH values showed opposite trend with a fall of about 8.4% in summer compared to winter (P < 0.001). Calcium levels were higher during the autumn with a rise of about 0.2 mg/dL in the mean calcium levels compared to spring and summer (P < 0.001). The odds ratio of calcium level above 11.5 mg/dL is highest in the autumn (OR = 1.275, P = 0.018).ConclusionWe show seasonal variation in serum 25-hydroxyvitamin D, PTH, and calcium levels in patients with PHPT. These seasonal variations cause transition to pathological values that may influence diagnosis and treatment of PHPT patients.     

Vitamin D deficiency promotes growth of MCF-7 human breast cancer in a rodent model of osteosclerotic bone metastasis

IntroductionBreast cancer metastases to bone are common in advanced stage disease. We have recently demonstrated that vitamin D deficiency enhances breast cancer growth in an osteolytic mouse model of breast cancer metastasis. In this study, we examined the effects of vitamin D deficiency on tumor growth in an osteosclerotic model of intra-skeletal breast cancer in mice.MethodsThe effects of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] on proliferation and apoptosis of MCF-7 breast cancer cells, and changes in the expression of genes within the vitamin D metabolic pathway (VDR, 1α- and 24-hydroxylase) were examined in vitro. MCF-7 breast cancer cells were injected intra-tibially into vitamin D deficient and vitamin D sufficient mice co-treated with and without osteoprotegerin (OPG). The development of tumor-related lesions was monitored via serial X-ray analysis. Tumor burden and indices of proliferation and apoptosis were determined by histology along with markers of bone turnover and serum intact PTH levels.ResultsIn vitro, MCF-7 cells expressed critical genes for vitamin D signalling and metabolism. Treatment with 1,25(OH)₂D₃ inhibited cell growth and proliferation, and increased apoptosis. In vivo, osteosclerotic lesions developed faster and were larger at endpoint in the tibiae of vitamin D deficient mice compared to vitamin D sufficient mice (1.49 ± 0.08 mm² versus 1.68 ± 0.15 mm², P < 0.05). Tumor area was increased by 55.8% in vitamin D deficient mice (0.81 ± 0.13 mm² versus 0.52 ± 0.11 mm² in vitamin D sufficient mice). OPG treatment inhibited bone turnover and caused an increase in PTH levels, while tumor burden was reduced by 90.4% in vitamin D sufficient mice and by 92.6% in vitamin D deficient mice. Tumor mitotic activity was increased in the tibiae of vitamin D deficient mice and apoptosis was decreased, consistent with faster growth.ConclusionVitamin D deficiency enhances both the growth of tumors and the tumor-induced osteosclerotic changes in the tibiae of mice following intratibial implantation of MCF-7 cells. Enhancement of tumor growth appears dependent on increased bone resorption rather than increased bone formation induced by these tumors.     

The associations of 25-hydroxyvitamin D levels,vitamin D binding protein gene polymorphisms,and race with risk of incident fracture-related hospitalization: Twenty-year follow-up in a bi-ethnic cohort (the ARIC Study)

BackgroundDeficient levels of 25-hydroxyvitamin D [25(OH)D] have been associated with increased fracture risk. Racial differences in fracture risk may be related to differences in bioavailable vitamin D due to single nucleotide polymorphism (SNP) variations in the vitamin D binding protein (DBP).MethodsWe measured 25(OH)D levels in 12,781 middle-aged White and Black participants [mean age 57 years (SD 5.7), 25% Black] in the ARIC Study who attended the second examination from 1990–1992. Participants were genotyped for two DBP SNPs (rs4588 and rs7041). Incident hospitalized fractures were measured by abstracting hospital records for ICD-9 codes. We used Cox proportional hazards models to evaluate the association between 25(OH)D levels and risk of fracture with adjustment for possible confounders. Interactions were tested by race and DBP genotype.ResultsThere were 1122 incident fracture-related hospitalizations including 267 hip fractures over a median of 19.6 years of follow-up. Participants with deficient 25(OH)D (< 20 ng/mL) had a higher risk of any fracture hospitalization [HR = 1.21 (95% CI 1.05–1.39)] and hospitalization for hip fracture [HR = 1.35 (1.02–1.79)]. No significant racial interaction was noted (p-interaction = 0.20 for any fracture; 0.74 for hip fracture). There was no independent association of rs4588 and rs7041 with fracture. However, there was a marginal interaction for 25(OH)D deficiency with rs7041 among Whites (p-interaction = 0.065). Whites with both 25(OH)D deficiency and the GG genotype [i.e. with predicted higher levels of DBP and lower bioavailable vitamin D] were at the greatest risk for any fracture [HR = 1.48 (1.10–2.00)] compared to Whites with the TT genotype and replete 25(OH)D (reference group).ConclusionsDeficient 25(OH)D levels are associated with higher incidence of hospitalized fractures. Marginal effects were seen in Whites for the DBP genotype associated with lower bioavailable vitamin D, but result inconclusive. Further investigation is needed to more directly evaluate the association between bioavailable vitamin D and fracture risk.     

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.     

Ethnic differences in parathyroid hormone secretion and mineral metabolism in response to oral phosphate administration

Ethnic differences in bone metabolism have been reported and it has been suggested that these may be partly due to prolonged exposure to an elevated plasma parathyroid hormone (PTH) concentration or a decreased sensitivity to PTH. We explored ethnic differences in bone and mineral metabolism by 5 days of oral phosphate (P) loading to stimulate PTH secretion. Healthy older people from UK (B), The Gambia (G) and China (C), 15 individuals from each sex and ethnic group, were studied. Blood and urine samples were collected before and 2 h after P dose on days 1, 4 and 5 and on a control day. The induced changes (%) in PTH and markers of mineral and bone metabolism after 2 h and over 5 days were examined.At baseline, PTH, 1,25(OH)₂D and bone turnover markers were higher in Gambian subjects than in British and Chinese subjects (P ≤ 0.01).2 h after P loading, ionized calcium (iCa) decreased and PTH and plasma P (P) increased in all groups (P ≤ 0.01, n.s. between groups). Urinary P to creatinine ratio (uP/Cr) increased, the increase being greater in Chinese subjects than in British and Gambian subjects on days 4 and 5 (P ≤ 0.01). By day 5, fasting iCa was decreased and P increased in British and Gambian (P ≤ 0.01) but not in Chinese subjects. Fasting PTH and uP/Cr increased in all groups. There were ethnic differences in changes in bone markers, but the relationship with changes in PTH was comparable between groups.In conclusion, ethnic differences in mineral metabolism in response to 5-day P loading were found. Chinese subjects showed a more rapid renal clearance of P than British and Gambian counterparts and there were differences between the groups in the skeletal response to P loading, but no evidence was found for resistance to the resorbing effects of PTH.     

High prevalence of vitamin D deficiency among middle-aged and elderly individuals in northwestern China: Its relationship to osteoporosis and lifestyle factors

PurposeVitamin D deficiency has reached epidemic proportions; this deficiency has been associated with osteoporosis and certain lifestyle factors in adults. This relationship is not well documented among the Lanzhou population in northwest China. This study sought to determine the prevalence of vitamin D deficiency and its risk factors in addition to its relationship with osteoporosis in a Chinese population living in Lanzhou.MethodsThis cross-sectional study involved 2942 men and 7158 women aged 40–75 years who were randomly selected from 3 communities in the Lanzhou urban district and examined medically. Levels of 25-hydroxy-vitamin D [25(OH)D] and other parameters were measured according to detailed inclusion criteria. Vitamin D deficiency was defined as serum 25(OH)D levels below 20 ng/mL. Calcaneus bone mineral density (BMD) was measured by quantitative ultrasound (QUS).ResultsThe prevalence of vitamin D deficiency (25(OH)D levels < 20 ng/mL) was present in 75.2% of the entire study population. Vitamin D deficiency was more prevalent in women (79.7%) than in men (64%; P < 0.001). Multiple logistic regression analysis revealed that the significant predictors of vitamin D deficiency included coronary heart disease (CHD), obesity, dyslipidemia, older age, female sex, and smoking (all P < 0.05), whereas tea intake, moderate physical activity, milk intake, vitamin D supplementation and sun exposure were protective (all P < 0.05). No significant difference in calcaneus BMD measured by QUS was noted between subjects with < 20 ng/mL and ≥ 20 ng/mL vitamin D levels (0.53 ± 0.13 vs. 0.54 ± 0.13; P = 0.089). The risk of having osteoporosis did not increase when vitamin D levels decreased from ≥ 20 ng/mL to < 20 ng/mL after multiple adjustments (OR = 1.00; 95% CI 0.85–1.16; P = 0.357).ConclusionsVitamin D deficiency is prevalent in the middle-aged and elderly northwestern Chinese population and is largely attributed to CHD, obesity, dyslipidemia, older age, female sex, and smoking. Reduced 25(OH)D levels are not associated with an increased osteoporosis risk.     

Secondary hyperparathyroidism and mortality in hip fracture patients compared to a control group from general practice

IntroductionPreviously, little attention has been paid as to how disturbances in the parathyroid hormone (PTH)–calcium–vitamin D-axis, such as secondary hyperparathyroidism (SHPT), relate to mortality amongst hip fracture patients. This study aimed to (1) determine if SHPT is associated with mortality in this group of patients, (2) investigate the association between serum (s-) PTH, s-total calcium, s-25-hydroxyvitamin D (s-25(OH)D) and mortality and (3) determine the prevalence of SHPT amongst hip fracture patients and a control group.MethodThe study included 562 hip fracture patients (HF) (age ≥ 70 years) admitted to a Danish university hospital. The hip fracture patients were prospectively enrolled in a dedicated hip fracture database. Each hip fracture patient was exactly matched according to age and sex with two controls randomly chosen from a control population of 21,778 subjects who had s-PTH, s-total calcium and s-25(OH)D measured at the Copenhagen General Practitioners Laboratory after referral from their general practitioner. The control group (Con) thus consisted of 1124 subjects.ResultsGeneral 1-year mortality: Con-female 8.4%, Con-male 15.3%, HF-female 24.6%, HF-male 33.3%, p < 0.0001 (log rank).SHPT and related 1-year mortalityCon-no SHPT 8.9%, Con-SHPT 16.8%, HF-no SHPT 22.7%, HF-SHPT 34.9%, p < 0.0001 (log rank). The mortality rates were higher for controls with SHPT (OR 2.06, 95% CI: 1.32–3.23), hip fracture patients without SHPT (OR 3.00, 95% CI: 2.14–4.20) and hip fracture patients with SHPT (OR 5.46, 95% CI: 3.32–8.97) compared to the controls without SHPT.Prevalence of SHPTCon 16%, HF 20%, p = 0.09 (Chi-square).ConclusionsOur study clearly shows that SHPT is significantly associated with mortality in both hip fracture patients and the control group. In the multivariate Cox regression analysis, s-PTH and s-total calcium were both significantly associated with mortality, whereas s-25(OH)D was not associated with mortality in this analysis. Our study furthermore indicates that SHPT is almost equally prevalent amongst the hip fracture patients and the control group.     

Impact of demographic,environmental, and lifestyle factors on vitamin D sufficiency in 9084 Japanese adults

BackgroundLittle is known about correlates of vitamin D status in Asian populations. In this study, we established the prevalence of vitamin D sufficiency in the Murakami region (latitude N38°13′) in Niigata, Japan, and examined demographic, environmental, and lifestyle factors that might be associated with vitamin D sufficiency, with the aim of clarifying the relative contributions of previously described determinants of vitamin D status as well as identifying new determinants in this Japanese population.MethodsThis study involved a cross-sectional analysis of baseline data obtained from a cohort study conducted in 2011–2013. Participants were 9084 individuals aged between 40 and 74 years who provided blood samples for the determination of plasma 25-hydroxyvitamin D [25(OH)D] concentrations. Lifestyle information was obtained from 8498 participants, with some missing values regarding different lifestyle factors. Multiple logistic regression analysis was used to obtain odds ratios for vitamin D sufficiency, which was defined as a plasma 25(OH)D concentration ≥ 75 nmol/L.ResultsThe prevalence of vitamin D sufficiency (i.e., plasma 25(OH)D concentration ≥ 75 nmol/L) was 9.1%, and significant associations were observed with male gender (P < 0.0001; OR = 2.37, 95% CI: 1.84–3.05), older age (P for trend < 0.0001), lower BMI (P for trend < 0.0001), higher METs score (P for trend = 0.0138), higher vitamin D intake (P for trend = 0.0467), summer season (P for trend < 0.0001), longer duration outdoors (P for trend = 0.0026), no sunscreen use (P = 0.0135; OR = 1.40, 95% CI: 1.07–1.82), higher salmon consumption (P for trend < 0.0001), higher alcohol consumption (P for trend < 0.0001), and lower coffee consumption (P for trend = 0.0025). Unlike other populations previously reported, vitamin D sufficiency was associated with older age.ConclusionsThe prevalence of vitamin D sufficiency (i.e., 25[OH]D ≥ 75 nmol/L) was low (9.1%) in this Japanese population. A number of demographic, environmental, and lifestyle factors are associated with vitamin D sufficiency, and thus lifestyle modification may present an opportunity to achieve vitamin D sufficiency.     

Age but not gender modulates the relationship between PTH and vitamin D

ContextIt is unclear whether the relationship between 25-OHD and PTH is modulated by age or gender.ObjectiveTo assess the 25-OHD–PTH relationship in 340 adolescents (10–17 years) and 443 elderly (65–85 years) of the same ethnic group, and living in the same sunny country.AssessmentsCalcium intake was estimated. Serum calcium, phosphorus, 25-OHD and PTH were measured. Body fat was determined by DXA.Results25-OHD levels were lower in the elderly in the overall group (p < 0.001) and within genders. 25-OHD levels were lower in females in the overall group and within age subgroups (p < 0.05). PTH levels were higher in the elderly in the overall population and in both genders (p < 0.001). There were no gender differences in PTH levels within age subgroups. For the same 25-OHD level, PTH levels were comparable across genders but were 1.5–2 folds higher in the elderly compared to adolescents (p < 0.001). PTH correlated positively with age (p < 0.001), body fat (p = 0.02), and negatively with calcium intake (p < 0.001), and 25-OHD (p < 0.001). The magnitude of the correlation with 25-OHD decreased after adjustment for age but not for gender. In multivariate analyses, age, 25-OHD and fat mass were independent predictors for PTH. In the elderly, after adjustment for serum creatinine, only 25-OHD and creatinine were independent predictors of PTH.ConclusionThe negative relationship between 25-OHD and PTH is modulated by age but not gender. Desirable 25-OHD levels derived from examining the 25-OHD–PTH relationship should therefore take into account the age of the population of interest.     

Low utility of serum 25–hydroxyvitamin D3 and 1, 25-dihydroxyvitamin D3 in predicting peripheral Treg and Th17 cell counts in ESRD and renal transplant patients

BackgroundVitamin D has shown an immune-modulatory effect in different studies. Vitamin D stimulates Tregs and inhibits Th17 cells. The immune-modulatory role of vitamin D in chronic kidney disease (CKD) and renal transplant patients is unclear. We measured whether different serum levels of vitamin D were associated with an increased or decreased presence of lymphocyte subsets including Treg and Th17 cells in end-stage renal disease (ESRD) and renal transplant recipients.MethodsEighty-seven renal transplant recipients and 53 end-stage renal disease (ESRD) patients were enrolled in this study. The absolute counts of CD4 + and CD8 + T, CD16 + CD56 + NK, CD19 + B, CD4 + CD25 + CD127- Foxp3 + (Tregs), Helios + Tregs, CD38 + Tregs, and CD4 + CD17 + (Th17) cells were analyzed in peripheral blood in both patient groups. In addition, serum 25 (OH) D₃, 1, 25 (OH)₂ D₃, IL-6, IL-17, IL-23, and TGF-β₁ were measured. The association between lymphocyte subset counts and 1, 25 (OH)₂ D₃ or 25 (OH) D₃ was studied, as was the association between serum IL-6, IL-17, IL-23, or TGF-β₁ and 1,25 (OH)₂ D₃ or 25 (OH) D₃.ResultsSerum 25 (OH) D₃ and 1,25 (OH)₂ D₃ levels were not independently associated with peripheral CD4 + T, CD19 + B, CD16 + CD56 + NK, Treg, or Th17 cell counts. In contrast to serum 25 (OH) D₃, serum1, 25 (OH)₂ D₃ was positively associated with CD8 + T cells counts in renal transplant recipients.ConclusionOur findings indicate low utility of serum 25 (OH) D₃ and 1, 25 (OH)₂ D₃ levels in predicting a change in lymphocyte subset counts in ESRD and renal transplant patients.     

Vitamin D levels in post-menopausal Korean women with a distal radius fracture

IntroductionThe purpose of this study was to investigate serum levels of vitamin D in post-menopausal Korean women with a distal radius fracture (DRF) and to determine if there is any association between vitamin D levels and bone-related variables such as bone mineral densities (BMDs), serum parathyroid hormone (PTH) levels and several bone turnover markers.Materials and methodsThe data of 104 postmenopausal women surgically treated for a distal radius fracture (DRF group) and 107 age-matched control patients without a fracture (control group) were compared. Serum vitamin D levels (25-hydroxycholecalciferol, 25(OH)D₃) were compared between the groups with consideration of age and seasonal variations. BMDs, serum PTH and several bone turnover markers, including serum osteocalcin, C-telopeptide and urine N-telopeptide, were measured and analysed to find any association with vitamin D levels.ResultsThe mean 25(OH)D₃ level was significantly lower in the DRF group compared to the control group (p < 0.001). In particular, patients in their sixth and seventh deciles in the DRF group had significantly lower 25(OH)D₃ levels than patients in the control group (p = 0.001 and 0.013, respectively). When seasonal variation was considered, significant differences of 25(OH)D₃ levels were found between the groups in autumn and winter. Hip BMDs were significantly lower in the DRF group than in the control group, and there was a positive correlation between serum 25(OH)D₃ levels and hip BMDs. Bone turnover markers were not significantly different between the two groups, although serum PTH levels were marginally higher in the DRF group (p = 0.08).ConclusionsPost-menopausal Korean women with a DRF were found to have significantly lower serum vitamin D levels than the control group, and vitamin D levels were particularly lower in women in their sixth and seventh deciles who may be a good target group for prevention of future fractures. Future investigation should focus on determining whether vitamin D supplementation can be helpful in preventing future fractures in patients with a DRF.     

Serum 25-hydroxyvitamin D level and incident type 2 diabetes in older men,the Osteoporotic Fractures in Men (MrOS) study

The association between vitamin D status and diabetes risk is inconsistent among observational studies, and most of the available studies have been with women. In the present study we investigated the association between serum 25-hydroxyvitamin D (25(OH)D) levels and incident type 2 diabetes (T2D) in older men (≥ 65 years old) who participated in the multisite Osteoporotic Fractures in Men (MrOS) study enrolled from March 2000 to April 2002.Baseline 25(OH)D levels were available in 1939 subjects without prevalent T2D. Clinical information, body mass index (BMI) and other factors related to T2D were assessed at the baseline visit. Incident diabetes, defined by self-report and medication use, was determined over an average follow-up of 6.4 years. At baseline, participants were, on average, 73.3 (± 5.7) years old, had a mean BMI in the overweight range (27.2 kg/m² ± 3.6) and had total serum 25(OH)D of 26.1 ng/ml (± 8.3). Incident diabetes was diagnosed in 139 subjects. Cox regression analysis showed a trend toward a protective effect of higher 25(OH)D levels with a lower risk of T2D (HR 0.87, 95% CI: 0.73–1.04 per 1 SD increase of 25(OH)D). After adjusted for BMI and other potential confounders, the relationship between 25(OH)D levels and incident diabetes was further attenuated (HR 1.03, 95% CI 0.85–1.25). No significant difference in the incidence of diabetes emerged after analyzing study subjects according to baseline 25(OH)D quartiles.In conclusion, 25(OH)D levels were not associated with incident T2D in older men.     

Incremento de la densidad mineral ósea en pacientes con hiperparatiroidismo terciario tras paratiroidectomía total y autotrasplante de glándula paratiroides

IntroductionChanges in bone metabolism and bone mineral density are observed in renal transplant patients with tertiary hyperparathyroidism. The objective of this work was to analyse the increase in bone mineral density, as well the laboratory results, after total parathyroidectomy and autotransplantation in renal transplant patients with tertiary hyperparathyroidism.Material and methodsA retrospective study was conducted in which the bone mineral density values at femoral and lumbar level were analysed, together with the serum levels of calcium, phosphorous, parathyroid hormone (PTH), and alkaline phosphatase in 13 renal transplant patients with tertiary hyperparathyroidism before and after total parathyroidectomy and autotransplantation of the parathyroid glands.ResultsParathyroidectomy is associated with an increase in bone mineral density at femoral and lumbar level, with an increase of 8.6 ± 6.7% at lumbar level, and 4 ± 16.1% at femoral level. The decrease in calcium after the parathyroidectomy was 2.8 mg/dL (95% CI; 1.9-4). The decrease in PTH was 172 pg/mL (95% CI; 98-354) and the decrease in alkaline phosphatase was 229 U/L (95% CI; 70-371).ConclusionsTotal parathyroidectomy and autotransplantation of the parathyroid glands in renal transplant patients with tertiary hyperparathyroidism increases the bone mineral density. Furthermore, the calcium, PTH and alkaline phosphatase returned to normal in the long-term.