Vitamin D status and sex hormone binding globulin: determinants of bone turnover and bone mineral density in elderly women

Evaluation of Trabecular Bone Microarchitecture and Bone Mineral Density in Young Women, Including Selected Hormonal Parameters

The absence of non-invasive methods for assessing bone material and structural changes is a significant diagnostic challenge. Dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) testing is the gold standard for osteoporosis diagnosis. BMD and the trabecular bone score (TBS) have facilitated targeted osteoporosis prevention and treatment in clinical settings. The findings from this study indicate that BMD modulation in young women is influenced by various hormones, potentially compromising the diagnostic precision of BMD for subclinical bone demineralization. A total of 205 women aged 19 to 37 underwent anthropometric measurements and hormonal tests. BMD was determined using DXA, and TBS values were computed from the lumbar spine L1-L4 segment. The multivariate analysis findings suggest that BMD might not be determined by hormones. The relationship between TBS and TSH was statistically significant in the univariate analysis, which indicates the efficacy of further studies to determine the link between TBS and specific hormones. Analyzing the strength of the correlation between TBS and hormones in the univariate analysis shows which factors are worth considering in further analyses. This makes it possible to create better techniques that will help identify young women who are at a higher risk of developing osteoporosis.

The impact of biological clock and sex hormones on the risk of disease

Molecular clocks are responsible for defining 24-h cycles of behaviour and physiology that are called circadian rhythms. Several structures and tissues are responsible for generating these circadian rhythms and are named circadian clocks. The suprachiasmatic nucleus of the hypothalamus is believed to be the master circadian clock receiving light input via the optic nerve and aligning internal rhythms with environmental cues. Studies using both in vivo and in vitro methodologies have reported the relationship between the molecular clock and sex hormones. The circadian system is directly responsible for controlling the synthesis of sex hormones and this synthesis varies according to the time of day and phase of the estrous cycle. Sex hormones also directly interact with the circadian system to regulate circadian gene expression, adjust biological processes, and even adjust their own synthesis. Several diseases have been linked with alterations in either the sex hormone background or the molecular clock. So, in this chapter we aim to summarize the current understanding of the relationship between the circadian system and sex hormones and their combined role in the onset of several related diseases.

Role of sex hormone-binding globulin in the free hormone hypothesis and the relevance of free testosterone in androgen physiology

According to the free hormone hypothesis, biological activity of a certain hormone is best reflected by free rather than total hormone concentrations. A crucial element in this theory is the presence of binding proteins, which function as gatekeepers for steroid action. For testosterone, tissue exposure is governed by a delicate equilibrium between free and total testosterone which is determined through interaction with the binding proteins sex hormone-binding globulin and albumin. Ageing, genetics and various pathological conditions influence this equilibrium, hereby possibly modulating hormonal exposure to the target tissues. Despite ongoing controversy on the subject, strong evidence from recent in vitro, in vivo and human experiments emphasizes the relevance of free testosterone. Currently, however, clinical possibilities for free hormone diagnostics are limited. Direct immunoassays are inaccurate, while gold standard liquid chromatography with tandem mass spectrometry (LC-MS/MS) coupled equilibrium dialysis is not available for clinical routine. Calculation models for free testosterone, despite intrinsic limitations, provide a suitable alternative, of which the Vermeulen calculator is currently the preferred method. Calculated free testosterone is indeed associated with bone health, frailty and other clinical endpoints. Moreover, the added value of free testosterone in the clinical diagnosis of male hypogonadism is clearly evident. In suspected hypogonadal men in whom borderline low total testosterone and/or altered sex hormone-binding globulin levels are detected, the determination of free testosterone avoids under- and overdiagnosis, facilitating adequate prescription of hormonal replacement therapy. As such, free testosterone should be integrated as a standard biochemical parameter, on top of total testosterone, in the diagnostic workflow of male hypogonadism.

Association of Vitamin D and Parathyroid Hormone Status With the Aging-Related Decline of Bone Microarchitecture in Older Men: The Prospective Structure of Aging Men's Bones (STRAMBO) Study

Poor vitamin D status and high parathyroid hormone (PTH) level are associated with impaired bone microarchitecture, but these data are mainly cross-sectional. We studied the association of the baseline PTH and 25-hydroxycholecalciferol (25OHD) levels with the prospectively assessed deterioration of bone microarchitecture and in estimated bone strength in older men. Distal radius and tibia bone microarchitecture was assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT) at baseline, then after 4 and 8 years in 826 men aged 60-87 years. At distal radius, total bone mineral density (Tt.BMD), cortical thickness (Ct.Th^d ), cortical area (Ct.Ar), cortical BMD (Ct.BMD), and trabecular BMD (Tb.BMD) decreased, whereas trabecular area (Tb.Ar) increased more rapidly in men with 25OHD ≤20 ng/mL versus the reference group (>30 ng/mL). Men with 25OHD ≤10 ng/mL had faster decrease in reaction force and failure load than men with 25OHD >30 ng/mL. At the distal tibia, Tt.BMD, Ct.Th^d , Ct.Ar, Ct.BMD, failure load, and reaction force decreased, whereas Tb.Ar increased more rapidly in men with 25OHD between 10 and 20 ng/mL versus the reference group. The results were similar when 12 ng/mL was used as a threshold of severe vitamin D deficiency. At distal radius, men with PTH levels above the median (>44 pg/mL) had more rapid decrease in Tt.BMD, Ct.Ar, Ct.BMD, Ct.Th^d , reaction force, and failure load, and more rapid increase in Tb.Ar versus the lowest quartile (≤34 pg/mL). At the distal tibia, men in the highest PTH quartile had faster decrease in Tt.BMD, Ct.Th^d , Ct.Ar, Ct.BMD, reaction force, and failure load and faster increase in Tb.Ar versus the lowest quartile. The results were similar in men with glomerular filtration rate >60 mL/min. The results were similar in men who took no vitamin D or calcium supplements for 8 years. In summary, vitamin D deficiency and secondary hyperparathyroidism are associated with more rapid prospectively assessed cortical and trabecular bone decline in older men. © 2022 American Society for Bone and Mineral Research (ASBMR).

SHBG, Bone Mineral Density, and Physical Function Among Injection Drug Users With and Without HIV and HCV

CONTEXT

Sex hormone-binding globulin (SHBG) is a glycoprotein that regulates the bioavailability of sex hormones and is higher in people with HIV (PWH) and hepatitis C virus (HCV). SHBG is associated with aging-related diseases, including osteoporosis and frailty in the general population. However, the relationship between SHBG concentration and bone mineral density (BMD) and physical function among PWH and HCV is unclear.

OBJECTIVE

This study aimed to evaluate the association between chronic infection with HIV and HCV and SHBG, and to assess the relationship of circulating SHBG concentrations with low BMD, physical function impairment, and frailty.

METHODS

A cross-sectional study was conducted of 278 HCV-exposed (HCV antibody positive) adults enrolled with and without HIV and HCV from the AIDS Linked to the IntraVenous Experience cohort study into 4 groups: HCV-/HIV-, HCV-/HIV+, HCV+/HIV-, and HCV+/HIV+. We evaluated the association between SHBG concentrations and grip strength, gait speed, Short Physical Performance Battery score, frailty (Fried Frailty Phenotype), and BMD (lumbar spine, total hip, and femoral neck T-score) by using adjusted multivariable regression stratified by sex.

RESULTS

SHBG concentrations were higher in women, in those with HIV RNA greater than 400 copies/mL (P = .02) and HCV RNA greater than 15 IU/mL (P < .001). In adjusted models, higher SHBG concentrations among women were statistically significantly associated with lower grip strength (-0.43 [95% CI, -0.77 to -0.081] kg/10 nmol/L, P < .05), higher odds of frailty (odds ratio, 1.49 [95% CI, 1.07 to 2.08], P < .05), and lower T-scores at the lumbar spine (-0.070 [95% CI, -0.15 to -0.001] SD/10 nmol/L T-score BMD, P < .05). Similar associations were not observed among men.

CONCLUSION

Higher SHBG concentrations are associated with the presence of HIV and HCV viremia. Among women, but not men, higher SHBG concentrations were associated with lower grip strength, higher odds of frailty, and lower lumbar spine BMD. The underlying mechanisms of these associations require further investigation.

Vitamin D status and its association with parathyroid hormone in 23,134 outpatients

In vitro studies indicate that 25-hydroxyvitamin D3 (25(OH)D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) inhibits the synthesis of parathyroid hormone (PTH). The degree of PTH inhibition in humans by circulating 25(OH)D and 1,25(OH)2D may be different. Moreover, age and sex as well as confounding factors like calcium and phosphate may likewise affect the relationship between vitamin D and PTH in humans. However, this was not done so far in adequately powered studies. We investigated the relationship between 25(OH)D as well as 1,25(OH)2D and intact parathyroid hormone (iPTH) in 23,134 outpatients (age mean: 59.81 years) from the Berlin-Brandenburg area of Germany with normal serum creatinine considering confounding factors like age, sex, calcium and phosphate. 25(OH)D and iPTH were inversely correlated (r = -0.17, p < 0.0001). The inverse linear correlation was observed over the entire spectrum of 25(OH)D concentrations - from low 25(OH)D concentrations to very high 25(OH)D concentrations. Multiple linear regression analysis revealed that this correlation was independent of age, sex, creatinine, calcium and phosphate (unstandardized coefficients B: -0.16, p < 0.0001). However, 1,25(OH)2D was only positively associated with iPTH in women (r = 0.05, p = 0.033) and in the subgroup of patients with lower 25(OH)D (25(OH)D< 40 ng/ml) (r = 0.09, p < 0.0001), which was also presented in multiple linear regression analysis (unstandardized coefficients B: 0.20, p = 0.001). Circulating 1,25(OH)2D does not contribute substantially to the regulation of PTH in middle aged and vitamin D sufficient outpatients from the Berlin-Brandenburg area of Germany with normal kidney function. Presumably, serum 25(OH)D that is converted to 1,25(OH)2D after uptake in the parathyroid chief cells plays the critical role.

Effects of High-Impact Weight-Bearing Exercise on Bone Mineral Density and Bone Metabolism in Middle-Aged Premenopausal Women: A Randomized Controlled Trial

This study examined the effects of high-impact weight-bearing exercise on bone mineral density (BMD) and bone metabolic markers in middle-aged premenopausal women. Forty middle-aged premenopausal women were initially enrolled, but thirty-one participants (40.34 ± 3.69 years) completed in the study. The subjects were randomly divided into two groups including the high-impact weight-bearing exercise group (HWE, n = 14) and control group (CON, n = 17). The HWE group participated in the exercise for 50 min a day, three days per week for four months, while the CON group maintained their regular lifestyle. The HWE program included 10 different high-impact weight-bearing exercises such as jumping and running. BMD was measured using DXA (Hologic, QDR 4500W, Marlborough, MA, USA). The bone metabolic markers including serum 25-(OH) D, intact parathyroid hormone (PTH), osteoprotegerin (OPG), osteopontin (OPN), receptor activator of nuclear factor κB ligand (RANKL), osteocalcin (OC), C-terminal telopeptide of type 1 collagen (CTX), and calcium were analyzed. The results showed that the BMDs of femur, lumbar, and forearm did not significantly change during the intervention period in both the HWE and CON groups. A significant decrease in bone formation markers such as OC (F = 10.514, p = 0.003, ηp2 = 0.266) and an increase in bone resorption marker including CTX (F = 8.768, p = 0.006, ηp2 = 0.232) were found only in the CON group, while these values did not change in the HWE group. There was a significant increase in serum 25-(OH) D (F = 4.451, p = 0.044, ηp2 = 0.133) in the HWE group. Our findings suggest that four months of HWE is not sufficient to improve BMD and bone metabolic markers, but this impact exercise program may prevent the age-associated changes in bone turnover markers in middle-aged premenopausal women.

Gender-Affirming Hormone Therapy and Bone Health: Do Different Regimens Influence Outcomes in Transgender Adults? A Narrative Review and Call for Future Studies

BACKGROUND

Gender-affirming hormone therapy (GAHT) influences bone health in transgender individuals. Several hormone preparations and administration routes are available for GAHT, but no studies have compared clinical and laboratory bone health measures across different GAHT regimens.

CONTENT

We searched PubMed (MEDLINE), Embase, and Google Scholar for studies measuring bone turnover markers and bone mineral density before and during GAHT in transgender adults. We summarized bone health data by hormone type and administration route (estrogen or testosterone; oral, transdermal/percutaneous, intramuscular). Among trans women, we also examined outcomes among regimens containing different adjunctive agents (antiandrogens or gonadotropin-releasing hormone analogs).

SUMMARY

Most hormone preparations maintained or increased areal bone mineral density among trans adults taking GAHT for at least 12 months from baseline. Different bone turnover markers were measured across studies, and we were unable to compare or comment on the direct influence of selected hormone preparations on these clinical laboratory measures. Larger and uniformed studies are needed to measure volumetric bone mineral density and biomarkers of bone metabolism in trans adults taking standardized GAHT regimens.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS/AMERICAN COLLEGE OF ENDOCRINOLOGY CLINICAL PRACTICE GUIDELINES FOR THE DIAGNOSIS AND TREATMENT OF POSTMENOPAUSAL OSTEOPOROSIS-2020 UPDATE

Objective: The development of these guidelines is sponsored by the American Association of Clinical Endocrinologists (AACE) Board of Directors and American College of Endocrinology (ACE) Board of Trustees and adheres with published AACE protocols for the standardized production of clinical practice guidelines (CPGs). Methods: Recommendations are based on diligent reviews of the clinical evidence with transparent incorporation of subjective factors, according to established AACE/ACE guidelines for guidelines protocols. Results: The Executive Summary of this 2020 updated guideline contains 52 recommendations: 21 Grade A (40%), 24 Grade B (46%), 7 Grade C (14%), and no Grade D (0%). These detailed, evidence-based recommendations allow for nuance-based clinical decision-making that addresses multiple aspects of real-world care of patients. The evidence base presented in the subsequent Appendix provides relevant supporting information for the Executive Summary recommendations. This update contains 368 citations: 123 (33.5%) evidence level (EL) 1 (highest), 132 (36%) EL 2 (intermediate), 20 (5.5%) EL 3 (weak), and 93 (25%) EL 4 (lowest). New or updated topics in this CPG include: clarification of the diagnosis of osteoporosis, stratification of the patient according to high-risk and very-high-risk features, a new dual-action therapy option, and transitions from therapeutic options. Conclusion: This guideline is a practical tool for endocrinologists, physicians in general, regulatory bodies, health-related organizations, and interested laypersons regarding the diagnosis, evaluation, and treatment of post-menopausal osteoporosis. Abbreviations: 25(OH)D = 25-hydroxyvitamin D; AACE = American Association of Clinical Endocrinologists; ACE = American College of Endocrinology; AFF = atypical femoral fracture; ASBMR = American Society for Bone and Mineral Research; BEL = best evidence level; BMD = bone mineral density; BTM = bone turnover marker; CI = confidence interval; CPG = clinical practice guideline; CTX = C-terminal telopeptide type-I collagen; DXA = dual-energy X-ray absorptiometry; EL = evidence level; FDA = U.S. Food and Drug Administration; FRAX® = Fracture Risk Assessment Tool; GI = gastrointestinal; HORIZON = Health Outcomes and Reduced Incidence with Zoledronic acid ONce yearly Pivotal Fracture Trial (zoledronic acid and zoledronate are equivalent terms); ISCD = International Society for Clinical Densitometry; IU = international units; IV = intravenous; LSC = least significant change; NOF = National Osteoporosis Foundation; ONJ = osteonecrosis of the jaw; PINP = serum amino-terminal propeptide of type-I collagen; PTH = parathyroid hormone; R = recommendation; ROI = region of interest; RR = relative risk; SD = standard deviation; TBS = trabecular bone score; VFA = vertebral fracture assessment; WHO = World Health Organization.

The Paradoxical Role of Uric Acid in Osteoporosis

Because of its high prevalence worldwide, osteoporosis is considered a serious public health concern. Many known risk factors for developing osteoporosis have been identified and are crucial if planning health care needs. Recently, an association between uric acid (UA) and bone fractures had been explored. Extracellular UA exhibits antioxidant properties by effectively scavenging free radicals in human plasma, but this benefit might be disturbed by the hydrophobic lipid layer of the cell membrane. In contrast, intracellular free oxygen radicals are produced during UA degradation, and superoxide is further enhanced by interacting with NADPH oxidase. This intracellular oxidative stress, together with inflammatory cytokines induced by UA, stimulates osteoclast bone resorption and inhibits osteoblast bone formation. UA also inhibits vitamin D production and thereby results in hyper-parathyroidism, which causes less UA excretion in the intestines and renal proximal tubules by inhibiting the urate transporter ATP-binding cassette subfamily G member 2 (ABCG2). At normal or high levels, UA is associated with a reduction in bone mineral density and protects against bone fracture. However, in hyperuricemia or gout arthritis, UA increases bone fracture risk because oxidative stress and inflammatory cytokines can increase bone resorption and decrease bone formation. Vitamin D deficiency, and consequent secondary hyperparathyroidism, can further increase bone resorption and aggravated bone loss in UA-induced osteoporosis.

Association between Vitamin D Levels and Nonalcoholic Fatty Liver Disease: Potential Confounding Variables

Nonalcoholic fatty liver disease (NAFLD), historically considered to be the hepatic component of the metabolic syndrome, is a spectrum of fat-associated liver conditions, in the absence of secondary causes, that may progress to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Disease progression is closely associated with body weight or fatness, dyslipidemia, insulin resistance, oxidative stress, and inflammation. Recently, vitamin D deficiency has been linked to the pathogenesis and severity of NAFLD because of vitamin D "pleiotropic" functions, with roles in immune modulation, cell differentiation and proliferation, and regulation of inflammation. Indeed, several studies have reported an association between vitamin D and NAFLD/NASH. However, other studies have failed to find an association. Therefore, we sought to critically review the current evidence on the association between vitamin D deficiency and NAFLD/NASH, and to analyze and discuss some key variables that may interfere with this evaluation, such as host-, environment-, and heritability-related factors regulating vitamin D synthesis and metabolism; definitions of deficient or optimal vitamin D status with respect to skeletal and nonskeletal outcomes including NAFLD/NASH; methods of measuring 25(OH)D; and methods of diagnosing NAFLD as well as quantifying adiposity, the cardinal link between vitamin D deficiency and NAFLD.

Serum parathyroid hormone is associated with increased cortical porosity of the inner transitional zone at the proximal femur in postmenopausal women: the Tromsø Study

Serum parathyroid hormone (PTH) was associated with increased bone turnover markers and cortical porosity of the inner transitional zone at the proximal femur. These results suggest that PTH through increased intracortical bone turnover leads to trabecularisation of inner cortical bone in postmenopausal women.

INTRODUCTION

Vitamin D deficiency leads to secondary hyperparathyroidism and increased risk for fractures, whereas its association with cortical porosity is less clear. We tested (i) whether serum 25-hydroxyvitamin D (25(OH)D) and PTH were associated with cortical porosity and (ii) whether the associations of 25(OH)D) and PTH with fracture risk are dependent on cortical porosity.

METHODS

This case-control study included 211 postmenopausal women, 54-94 years old, with prevalent fractures and 232 controls from the Tromsø Study. Serum 25(OH)D, PTH, and bone turnover markers (procollagen type I N-terminal propeptide [PINP] and C-terminal cross-linking telopeptide of type I collagen [CTX]) were measured. Femoral subtrochanteric cortical and trabecular parameters were quantified using computed tomography, and femoral neck areal bone mineral density (FN aBMD) was quantified using dual-energy X-ray absorptiometry.

RESULTS

Compared with controls, fracture cases exhibited reduced serum 25(OH)D and increased PTH, PINP, and CTX, increased femoral subtrochanteric cortical porosity, and reduced cortical thickness and FN aBMD (all, p < 0.05). Serum 25(OH)D was not associated with cortical parameters (all, p > 0.10). PTH was associated with increased PINP, CTX, and cortical porosity of the inner transitional zone and reduced trabecular bone volume/tissue volume and FN aBMD (p ranging from 0.003 to 0.054). Decreasing 25(OH)D and increasing PTH were associated with increased odds for fractures, independent of age, height, weight, calcium supplementation, serum calcium, cortical porosity, and thickness.

CONCLUSIONS

These data suggest that serum PTH, not 25(OH)D, is associated with increased intracortical bone turnover resulting in trabecularisation of the inner cortical bone; nevertheless, decreasing 25(OH)D) and increasing PTH are associated with fracture risk, independent of cortical porosity and thickness.

Vitamin D and parathyroid hormone are associated with gait instability and poor balance performance in mid-age to older aged women

CONTEXT

Vitamin D status and parathyroid hormone (PTH) levels influence the risk of accidental falls in older people, but the mechanisms underlying this effect remain unclear.

OBJECTIVE

Investigate the relationship between circulating PTH and 25 hydroxyvitamin D (25-OHD) levels and clinical tests of gait stability and balance as physical fall risk factors. We hypothesized that high levels of PTH and low 25-OHD levels would be significantly associated with gait stability and decreased balance performance.

DESIGN

Observational cohort study.

SETTING

Australian community.

PARTICIPANTS

119 healthy, ambulatory female twin adults aged 47-80 years residing in Victoria, Australia.

OUTCOME MEASURES

Serum PTH and 25-OHD levels with clinical tests of gait stability [double support duration (DSD)] and dynamic balance (Step Test). Associations were investigated by regression analysis and by comparing groups divided by tertiles of PTH (<3.5, 3.5-4.9, >4.9pmol/L) and 25-OHD (<53, 53-75, >75 nmol/L) using analysis of variance.

RESULTS

Serum PTH was associated positively with DSD, with an increase of 10.6-15.7% when the mid and highest PTH tertiles were compared to the lowest tertile (p <0.025) when 25-OHD was included in the regression analysis. 25-OHD was significantly associated with DSD (greater by 10.6-11.1% when lowest and mid-tertiles compared with the highest 25-OHD tertile) (p <0.025) and dynamic balance (better performance by 12.6% in the highest compared with the lowest 25OHD tertile) (p <0.025).

CONCLUSION

These findings reveal an important new relationship between parathyroid hormone and gait stability parameters and add to understanding of the role of 25-OHD in motor control of gait and dynamic balance in community-dwelling women across a wide age span.

Skeletal effects of vitamin D deficiency among patients with primary hyperparathyroidism

Little is known about the association between vitamin D deficiency and the skeletal phenotypes in primary hyperparathyroidism (PHPT) patients. A low 25-hydroxyvitamin D level was associated with a low bone mineral density and deteriorated hip geometry in women with PHPT in an Asian population where vitamin D deficiency is prevalent.

INTRODUCTION

Few studies have examined the effect of vitamin D deficiency on the bone health of primary hyperparathyroidism (PHPT) patients.

METHODS

We investigated the skeletal effects of vitamin D deficiency in 79 PHPT patients by assessing bone mineral density (BMD), the trabecular bone score (TBS), and hip geometry, which were measured using dual-energy X-ray absorptiometry (27 men with median age 60 years [53;69]; 52 postmenopausal women with median age of 57 years [53;67]). Cross-sectional data were collected from subjects enrolled in an ongoing PHPT cohort study at Seoul National University Hospital from March 2008 to December 2015.

RESULTS

We classified PHPT patients according to 25-hydroxyvitamin D (25(OH)D) levels (<20 vs. ≥20 ng/ml). After adjusting for age and body mass index, women with vitamin D deficiency had lower BMDs at the lumbar spine (LS) and femur neck (FN) than women who had sufficient levels of vitamin D (LS, 0.903 ± 0.138 vs. 0.998 ± 0.184 g/cm²; FN, 0.715 ± 0.084 vs. 0.791 ± 0.113 g/cm²; P < 0.05). However, the total hip BMD and the TBS were not significantly different between the two groups. In the hip geometry analysis, the cross-sectional area, cross-sectional moment of inertia, and section modulus were also significantly lower in women with vitamin D deficiency than in those without. No significant difference was found in the BMD, TBS, or hip geometry according to 25(OH)D levels in men.

CONCLUSION

Vitamin D deficiency may be associated with a low BMD and deteriorated hip geometry in postmenopausal women with PHPT.

Cut-points for associations between vitamin D status and multiple musculoskeletal outcomes in middle-aged women

This was the first study examining optimal vitamin D status for musculoskeletal health in middle-aged women. A 25-hydroxyvitamin D level of at least 29 to 33 nmol/L appears required for optimal musculoskeletal health, but the current cut-off of 50 nmol/L may be warranted.

INTRODUCTION

This study aimed to determine whether cut-points exist for associations between serum 25-hydroxyvitamin D (25OHD) and musculoskeletal health outcomes in middle-aged women, below which greater 25OHD levels are associated with musculoskeletal health benefits and above which no such associations exist.

METHODS

This is a cross-sectional study of 344 women aged 36-57 years. Cut-points for associations of serum 25OHD with lumbar spine (LS) and femoral neck (FN) bone mineral density (BMD), lower limb muscle strength (LMS), timed up and go test (TUG), functional reach test (FRT), lateral reach test (LRT), and step test (ST) were explored using locally weighted regression smoothing and nonlinear least-squares estimation, and associations above and below the identified cut-points were estimated using segmented regression.

RESULTS

The prevalence of low 25OHD was 28 % (<50 nmol/L). Significant cut-points (nmol/L) were identified for FN BMD 31 (95 % confidence interval (CI): 18, 43), LS BMD 31 (17, 45), TUG 30 (24, 36), ST 33 (24, 31), FRT 31 (18, 43), and LMS 29 (8, 49) but not LRT (42 (-8, 93). Below these cut-points, there were beneficial associations between higher 25OHD level and each outcome, while above the cut-points, there were no beneficial associations.

CONCLUSIONS

In middle-aged women, there are thresholds for associations between serum 25OHD concentrations and bone density and most balance measures, suggesting that 25OHD levels of at least 29 to 33 nmol/L are required for optimal musculoskeletal health in this population. The current cut-off of 50 nmol/L may be higher than needed for some outcomes but appears warranted overall.

Cholecalciferol Additively Reduces Serum Parathyroid Hormone and Increases Vitamin D and Cathelicidin Levels in Paricalcitol-Treated Secondary Hyperparathyroid Hemodialysis Patients

Background: Active Vitamin D analogues are used clinically for prevention and treatment of secondary hyperparathyroidism (SHPT) in hemodialysis (HD) patients. Nutritional vitamin D supplementation is used for additional local parathyroid (PTH) suppression, with lower incidence of hypercalcemia and hyperphosphatemia. This study evaluates the possible beneficial effects of combined vitamin D treatment (paricalcitol and cholecalciferol). Methods: Sixty HD patients with serum parathyroid hormone (iPTH) >300 pg/mL were enrolled. All patients administered 2 mcg/day of paricalcitol and were randomly allocated into control group (placebo) or study group (cholecalciferol) for 16 weeks. Serum 25(OH)D₃, iPTH and human cathelicidin (hCAP-18) were measured at baseline and during follow-up. Results: iPTH levels decreased in the study group appropriately and were more significantly decreased at 16 weeks. Study group had significantly increased 25(OH)D₃ levels. In addition, the study group had significantly increased serum hCAP-18 levels compared with control group. Correlation analysis showed a significant correlation between the percentage increase in serum hCAP-18 and 25(OH)D₃ levels. Conclusions: Cholecalciferol, in combination with paricalcitol, additively lowers the iPTH levels in a significant number of patients after 16 weeks of supplementation. A dose of 5000 IU/week of cholecalciferol could maintain serum 25(OH)D₃ levels above 30 ng/dL as early as 8 weeks after beginning supplementation. Doubling of serum cathelicidin levels were noted after 16 weeks of cholecalciferol supplementation in 40% of study patients.

Association between serum 25-hydroxyvitamin D levels and bone mineral density in normal postmenopausal women

Aim:

This study was conducted with the objective of assessing serum 25-hydroxyvitamin D (25(OH)D) in postmenopausal women (PMW), to detect osteopenia or osteoporosis in PMW and to establish a correlation between serum 25(OH)D levels and bone mineral density (BMD).

Materials and Methods:

A total of 100 healthy PMW were selected, and a prospective observational study was conducted to correlate the BMD with serum 25(OH)D levels. Their laboratory investigations along with serum 25(OH)D levels were done. Their BMD was assessed with dual-energy X-ray absorptiometry at lumbar spine and neck of femur; T-scores were derived. Correlation analysis was done to investigate the relationship between serum 25(OH)D levels and BMD.

Results:

The proportion of osteoporosis at the hip was 31.9% in deficient group, 16.1% in insufficient, and 18.2% in sufficient group and at lumbar spine, it was 27.7%, 16.1%, and 22.7%, respectively. Forty-seven percent of PMW had deficient (<20 ng/ml) serum 25(OH)D levels and 31% had insufficiency. T-score at hip in deficient group was −2.05 ± 0.25, and in an insufficient group, it was −1.79 ± 0.13; T-score at lumbar spine was −1.92 ± 0.12 and −1.79 ± 0.12, respectively, but both were not statistically significant. Osteoporosis was seen in 24%, osteopenia in 55% at hip level and 23% and 59% respectively at lumbar spine. There was no association between serum 25(OH)D levels and BMD neither at hip nor at lumbar spine (P = 0.51 and P = 0.79 respectively).

Conclusion:

In this study, among our cohort of patients there was no correlation between serum 25(OH)D levels and BMD. However, Vitamin D deficiency coexists with low BMD. Vitamin D insufficiency is a common risk factor for osteoporosis associated with increased bone remodeling and low bone mass.

Determinants of parathyroid hormone response to vitamin D supplementation: a systematic review and meta-analysis of randomised controlled trials

This systematic review aimed to assess the determinants of the parathyroid hormone (PTH) level response to vitamin D supplementation. We searched Medline, Google Scholar and the reference lists of previous reviews. All randomised controlled trials (RCT) on vitamin D supplementation that involved apparently healthy human subjects with a report of PTH were selected. Potential studies were screened independently and in duplicate. Results are summarised as mean differences with 95% confidence intervals. Quality assessment, subgroup analysis, meta-analysis and meta-regression analysis were carried out. Thirty-three vitamin D supplementation RCT were included. Vitamin D supplementation significantly raised circulating 25-hydroxyvitamin D (25(OH)D) with significant heterogeneity among studies with a pooled mean difference (PMD) of 15.5 ng/ml (test for heterogeneity: P<0·001 and I 2=97·3%). Vitamin D supplementation significantly reduced PTH level with PMD of -8·0 pg/ml, with significant heterogeneity ((test for heterogeneity: P<0·001) and the I 2 value was 97·3%). In the subgroup analyses, the optimum treatment effect for PTH was observed with Ca doses of 600-1200 mg/d (-22·48 pg/ml), after the duration of a >12-month trial (-18·36 pg/ml), with low baseline 25(OH)D concentration of <20 ng/ml (-16·70 pg/ml) and in those who were overweight and obese (-18·11 pg/ml). Despite the present meta-analysis being hindered by some limitations, it provided some interesting evidence, suggesting that suppression of PTH level needs higher vitamin D intake (75 μg/d) than the current recommendations and longer durations (12 months), which should be taken into account for nutritional recommendations.

Vitamin D status in men with psoriatic arthritis: a case-control study

We determined hypovitaminosis D prevalence in men with psoriatic arthritis. This is a cross-sectional, analyst blinded, age- and sex-matched, case-control study. Men with psoriatic arthritis have significantly lower 25-hydroxyvitamin D levels. Men with psoriatic arthritis are at increased odds of suffering from hypovitaminosis D.

INTRODUCTION

Skeletal manifestations as a result of abrupted bone metabolism may be predominant in psoriatic arthritis (PsA). Vitamin D plays a vital role in maintenance of skeletal health and is known to modulate the immune system in various autoimmune diseases including PsA. The aim of the present study was to determine the prevalence of hypovitaminosis D in a treatment naïve, de novo psoriatic arthritis male cohort in a cross-sectional, analyst blinded, age- and sex-matched, case-control study.

METHODS

25 hydroxyvitamin D (25OHD), parathyroid (PTH), osteocalcin (OC) and C-terminal telopeptides of type-I collagen (CTx) levels, and lumbar spine and femoral neck bone mineral density were compared between 53 PsA and controls.

RESULTS

The prevalence of hypovitaminosis D (25 hydroxyvitamin D (25OHD) levels <75 nmol/L) was 81 and 57 % in the PsA and control groups, respectively. Compared to the healthy controls, 25OHD (67.2 (12-137) nmol/L vs. 51.9 (15-95) nmol/L; p = 0.001) was significantly lower, and osteocalcin (13.6 (5-33) μg/L vs. 18.2 (6-35) μg/L; p = 0.003) and C-terminal telopeptides of type-I collagen (0.20 (0.01-0.71) μg/L vs. 0.28 (0.06-0.69) μg/L; p = 0.008) were significantly higher in the PsA group. A significant association was found between hypovitaminosis D and PsA; the odds for patients with PsA of having hypovitaminosis D was 3.297 (95 % confidence interval 1.372 to 7.922).

CONCLUSION

The results of this study suggest that men with PsA have significantly lower 25-hydroxyvitamin D levels, and furthermore, men with PsA are at statistically significant increased odds of suffering from hypovitaminosis D.

Vitamin D and health: the need for more randomized controlled trials

The importance of vitamin D for calcium absorption and bone health is undisputed. In addition, vitamin D may also be important for more than the skeleton as low serum levels of 25-hydroxyvitamin D (25(OH)D) have been associated with a number of diseases like cardiovascular disease, diabetes, cancer and infections. This is mainly based on observational studies and proof of causal relations from randomized controlled trials (RCTs) are lacking. At present several large RCTs including from 2152 to 25,000 subjects and with cardiovascular disease and cancer as endpoints are ongoing. Results are expected within 3-5 years, and hopefully these studies will give us a definite answer on need for vitamin D supplementation. However, since vitamin D deficiency (serum 25(OH)D <50nmol/L) has not been an inclusion criterion in these studies, there is a risk of a null effect. If so, one has to establish the effects of vitamin D in truly vitamin D deficient subjects, studies that in retrospect obviously should have been the starting point for RCTs on vitamin D and health. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

Lifestyle and osteoporosis

Osteoporosis is associated with a number of lifestyle factors, including nutritional factors such as intake of calcium, protein, dairy food, fruits and vegetables and vitamin D status, and behavioural factors such as physical activity, smoking and alcohol consumption. Ensuring adequate calcium intake and vitamin D status and having regular weight-bearing physical activity throughout life are important for bone health and the prevention of osteoporosis and related fractures. Studies have shown that smoking and excessive alcohol intake have adverse effects on bone health and increase the risk of fracture. There is evidence suggesting that adequate protein intake and higher intake of fruits and vegetables are beneficial to bone health.

Calcium and vitamin D supplementation: state of the art for daily practice

BACKGROUND

Calcium and vitamin D play an essential role in bone metabolism but deficiency and/or inadequate intake are common.

OBJECTIVES

To describe a practical approach based on the literature regarding clinically important aspects of calcium and vitamin D supplementation.

METHODS

A systematic evaluation of relevant literature in Medline was conducted. We included physiological studies, publications on relevant guidelines, meta-analysis, randomized clinical trials, and cohort studies.

RESULTS

An adequate calcium intake and vitamin D supplementation is recommended in most guidelines xon fracture prevention. Daily supplementation with 800 IU is advocated in most guidelines, appears to be safe, and with this approach it is generally not necessary to determine vitamin D levels. There are no data on additional effects of loading doses of vitamin D on fracture or fall prevention. Calcium supplementation should be tailored to the patient's need: usually 500 mg per day is required. The intestinal absorption of calcium citrate is approximately 24% better than that of calcium carbonate independent of intake with meals. Data on difference between calcium absorption with calcium carbonate compared to calcium citrate with simultaneous use of proton pump inhibitors are lacking. Concern has arisen about a possible link between calcium supplementation and an increased risk of myocardial infarction. Probably only well-designed prospective randomized controlled trials will be able to allow definite conclusions on this subject.

CONCLUSION

Daily supplementation with 800 IU vitamin D is a practical and safe strategy without the need for prior determination of vitamin D levels. Calcium supplementation should be tailored to the patient's need based on total daily dietary calcium intake. In most patients 500 mg per day is required to achieve a total intake of 1,200 mg, or in some 1,000 mg per day. More calcium is absorbed from calcium citrate compared to calcium carbonate.

Is bone loss linked to chronic inflammation in antiretroviral-naive HIV-infected adults? A 48-week matched cohort study

OBJECTIVE

Antiretroviral therapy (ART) has been implicated in bone loss in HIV. The role of inflammation and vitamin D is unclear and better investigated in ART-naive individuals.

DESIGN AND METHODS

This is a 48-week, prospective cohort study to compare baseline and change in hip and spine bone mineral density (BMD) measured by dual-energy X-ray absorptiometry in HIV-infected, ART-naive adults and healthy controls matched by age, sex, and race. We also studied associations between bone loss and inflammation markers and plasma 25-hydroxyvitamin D [25(OH)D] using logistic regression.

RESULTS

Forty-seven HIV-infected adults and 41 controls were included. Baseline 25(OH)D, BMD at total hip, trochanter, and spine, and prevalence of osteopenia and osteoporosis were similar between groups. In the HIV-infected group, total hip and trochanter, but not spine, BMD decreased over 48 weeks [hip -0.005 (-0.026-0.008) g/cm², P = 0.02 within group; trochanter -0.013 (-0.03-0.003), P < 0.01]. BMD did not change at any site within controls. The HIV-infected group was more likely to have bone loss at the trochanter (P = 0.03). This risk persisted after adjustment for age, sex, race, BMI, smoking, and hepatitis C (odds ratio 4, 95% confidence interval 1.2-15.8). In the HIV-infected group, higher interleukin-6 concentrations (P = 0.04) and Caucasian race (P < 0.01) were independently associated with progression to osteopenia or osteoporosis, but not 25(OH)D levels.

CONCLUSION

BMD at the total hip and trochanter sites decreased in the HIV-infected, ART-naive adults, but not controls, over this 48-week study. Higher serum interleukin-6 concentrations were associated with progression to osteopenia or osteoporosis status in the HIV-infected group.

Treadmill running reduces parathyroid hormone concentrations during recovery compared with a nonexercising control group

CONTEXT

Lower PTH concentrations reported in the hours after acute, endurance exercise compared with preexercise levels might be influenced by factors such as circadian fluctuations.

OBJECTIVE

The objective of the study was to compare postexercise PTH concentrations with a nonexercising control group.

DESIGN AND SETTING

A laboratory-based study with a crossover design, comparing a 60-minute (at 10:30 am) bout of treadmill running at 65% of the maximal rate of oxygen uptake (exercise) with semirecumbent rest (CON). Blood samples were obtained immediately before (baseline 10:15 am) and after (11:30 am) exercise and during recovery (12:30 am, 1:30 pm, and 2:15 pm).

PARTICIPANTS

Ten physically active men (mean ± 1 SD, age 26 ± 5 y; body mass 78.3 ± 5.8 kg; maximal rate of oxygen uptake 57.3 ± 6.9 mL/kg(-1) · min(-1)) participated in the study.

MAIN OUTCOME MEASURES

PTH, albumin-adjusted calcium, and phosphate concentrations were measured.

RESULTS

PTH concentrations increased (+85%, P < .01) during exercise and were higher than in CON immediately at the end of exercise (4.5 ± 1.9 vs 2.6 ± 0.9 pmol/L(-1), P < .05). In the postexercise period (12:30-2:15 pm), PTH was not different compared with baseline but was lower compared with CON at 1:30 pm (-22%; P < .01) and tended to be lower at both 12:30 pm (-12%; P = .063) and 2:15 pm (-13%; P = .057). Exercise did not significantly affect the albumin-adjusted calcium concentrations, whereas phosphate was higher than CON immediately after exercise (1.47 ± 0.17 vs 1.03 ± 0.17 pmol/L(-1), P < .001) and was lower at 1:30 pm (-16%: P < .05).

CONCLUSIONS

Lower PTH concentrations after acute endurance running compared with a rested control condition suggest a true effect of exercise.

Predictors of vitamin D deficiency and insufficiency in adult Bahrainis: a cross-sectional study

OBJECTIVE

High prevalence of hypovitaminosis D has been reported to be common in different regions of the Middle East. The objective of the present study was to examine the predictors of vitamin D deficiency and insufficiency in Bahrainis.

DESIGN

A cross-sectional study.

SETTING

Blood transfusion volunteers at a blood bank.

SUBJECTS

Serum levels of total 25-hydroxyvitamin D, bone markers and other parameters such age, sex, season and clothing style in the 500 healthy Bahrainis were investigated.

RESULTS

In the entire cohort the prevalence of vitamin D deficiency was 49.4% and the relative risk of vitamin D deficiency increased significantly by 1.1, 1.2, 1.5, 1.7 and 1.2 fold with younger age group (P = 0.03), hyperparathyroidism (P = 0.01), low serum Ca (P < 0.001), warm and hot months of the year (P < 0.0001) and female sex (P = 0.002), respectively. In females the prevalence of vitamin D deficiency was 67.6% and the relative risk of vitamin D deficiency increased significantly by 1.1, 1.2, 1.2, 1.2 and 1.4 fold with younger age group (P = 0.04), hyperparathyroidism (P = 0.03), low serum Ca (P = 0.001), warm and hot months of the year (P = 0.001) and conservative clothing style (P = 0.04), respectively. In contrast, in males the prevalence of vitamin D deficiency was 31.2% and the relative risk of vitamin D deficiency was increased by 1.6 fold in warm and hot months of the year (P < 0.0001).

CONCLUSIONS

High prevalence of low circulating levels of vitamin D and the relative risk factors associated with vitamin D deficiency and insufficiency observed in the present study suggest an urgent need for public health interventions including vitamin D food fortification in Bahrain.

Vitamin D status and its relationship with body composition, bone mineral density and fracture risk in urban central south Chinese postmenopausal women

AIMS

This study was designed to assess vitamin D (25(OH)D) status and its relationship with bone mineral density (BMD) and fracture risk, which was determined using the FRAX algorithm, among postmenopausal central south Chinese women, and to identify the risk factors for vitamin D deficiency and osteoporosis.

METHODS

This cross-sectional study involved 578 healthy postmenopausal central south Chinese women. Fat mass and BMD at lumbar spine (L1-L4), femur neck and total hip were measured with dual X-ray absorptiometry. Serum levels of 25(OH)D, parathyroid hormone and creatinine were measured. The 10-year probabilities of hip and major osteoporotic fracture were calculated by the FRAX model.

RESULTS

Approximately 72.1% women were vitamin D deficient (25(OH)D <50 nmol/l). Serum 25(OH)D levels did not correlate with body mass index (BMI), fat mass and weight. They positively correlated with all BMDs (p < 0.05) and negatively correlated with both 10-year fracture probabilities (p < 0.05). BMI ≤19 and age ≥65 years were risk factors for osteoporosis at all sites.

CONCLUSIONS

Vitamin D deficiency was prevalent among postmenopausal central south Chinese women. Serum 25(OH)D levels were correlated with all BMDs and negatively correlated with both 10-year fracture probabilities.

Microstructural, densitometric and metabolic variations in bones from rats with normal or altered skeletal states

Background

High resolution μCT, and combined μPET/CT have emerged as non-invasive techniques to enhance or even replace dual energy X-ray absorptiometry (DXA) as the current preferred approach for fragility fracture risk assessment. The aim of this study was to assess the ability of µPET/CT imaging to differentiate changes in rat bone tissue density and microstructure induced by metabolic bone diseases more accurately than current available methods.

Methods

Thirty three rats were divided into three groups of control, ovariectomy and vitamin-D deficiency. At the conclusion of the study, animals were subjected to glucose (¹⁸FDG) and sodium fluoride (Na¹⁸F) PET/CT scanning. Then, specimens were subjected to µCT imaging and tensile mechanical testing.

Results

Compared to control, those allocated to ovariectomy and vitamin D deficiency groups showed 4% and 22% (significant) increase in ¹⁸FDG uptake values, respectively. DXA-based bone mineral density was higher in the vitamin D deficiency group when compared to the other groups (cortical bone), yet μCT-based apparent and mineral density results were not different between groups. DXA-based bone mineral density was lower in the ovariectomy group when compared to the other groups (cancellous bone); yet μCT-based mineral density results were not different between groups, and the μCT-based apparent density results were lower in the ovariectomy group compared to the other groups.

Conclusion

PET and micro-CT provide an accurate three-dimensional measurement of the changes in bone tissue mineral density, as well as microstructure for cortical and cancellous bone and metabolic activity. As osteomalacia is characterized by impaired bone mineralization, the use of densitometric analyses may lead to misinterpretation of the condition as osteoporosis. In contrast, µCT alone and in combination with the PET component certainly provides an accurate three-dimensional measurement of the changes in both bone tissue mineral density, as well as microstructure for cortical and cancellous bone and metabolic activity.

Vitamin D deficiency and low bone mineral density in native Chinese rheumatoid arthritis patients

OBJECTIVE

We aimed to examine the risk factors related to the development of osteoporosis in rheumatoid arthritis (RA) patients and whether there is an association among the changes in bone mineral density (BMD), disease activities (modified DAS28), serum 25-hydroxyvitamin D (25OHD) levels, and disease duration.

METHODS

There were 110 patients with RA and 110 age- and sex-matched healthy controls who were concurrently studied. All of the patients underwent the following measurements: erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, and serum 25OHD. Dual-energy X-ray absorptiometry (DEXA) was also used to measure the BMD of the left femur at the time of recruitment. Patients taking vitamin D supplement or corticosteroids were excluded.

RESULTS

The incidences of osteopenia (45.6% vs. 36.4%, P = 0.170) and osteoporosis (33.6% vs. 5.45%, P = 0.000) were higher in the RA patients than in the healthy controls. There was a significant negative correlation between vitamin D levels and DAS28 (r = -0.325, P = 0.001) and a significant positive correlation between vitamin D levels and BMD (r = 0.422, P = 0.000). The multiple regression analysis revealed that 25OHD levels were significantly correlated with disease activity and BMD (F = 11.087, P = 0.000). Stepwise multiple regression analysis showed that serum 25OHD levels were the significant predictors for low BMD and high disease activity (DAS28) in RA patients.

CONCLUSION

The incidences of osteoporosis and osteopenia were higher in RA patients compared to the age- and gender-matched healthy controls. Low serum 25OHD levels correlate with low BMD and high disease activity in RA patients.

Hip bone loss is attenuated with 1000 IU but not 400 IU daily vitamin D3: a 1-year double-blind RCT in postmenopausal women

Few year-long vitamin D supplementation trials exist that match seasonal changes. The aim of this study was to determine whether daily oral vitamin D3 at 400 IU or 1000 IU compared with placebo affects annual bone mineral density (BMD) change in postmenopausal women in a 1-year double-blind placebo controlled trial in Scotland. White women aged 60 to 70 years (n = 305) were randomized to one of two doses of vitamin D or placebo. All participants started simultaneously in January/February 2009, attending visits at bimonthly intervals with 265 (87%) women attending the final visit and an additional visit 1 month after treatment cessation. BMD (Lunar iDXA) and 1,25-dihydroxyvitamin D[1,25(OH)2 D], N-terminal propeptide of type 1 collagen [P1NP], C-terminal telopeptide of type I collagen [CTX], and fibroblast growth factor-23 [FGF23] were measured by immunoassay at the start and end of treatment. Circulating PTH, serum Ca, and total 25-hydroxyvitamin D [25(OH)D] (latter by tandem mass spectrometry) were measured at each visit. Mean BMD loss at the hip was significantly less for the 1000 IU vitamin D group (0.05% ± 1.46%) compared with the 400 IU vitamin D or placebo groups (0.57% ± 1.33% and 0.60% ± 1.67%, respectively) (p < 0.05). Mean (± SD) baseline 25(OH)D was 33.8 ± 14.6 nmol/L; comparative 25(OH)D change for the placebo, 400 IU, and 1000 IU vitamin D groups was -4.1 ± 11.5 nmol/L, +31.6 ± 19.8 nmol/L, and +42.6 ± 18.9 nmol/L, respectively. Treatment did not change markers of bone metabolism, except for a small reduction in PTH and an increase in serum calcium (latter with 1000 IU dose only). The discordance between the incremental increase in 25(OH)D between the 400 IU and 1000 IU vitamin D and effect on BMD suggests that 25(OH)D may not accurately reflect clinical outcome, nor how much vitamin D is being stored.

Vitamin D: do we get enough? A discussion between vitamin D experts in order to make a step towards the harmonisation of dietary reference intakes for vitamin D across Europe

On September 29, 2011, acknowledged experts in the field of vitamin D, mainly European, were brought together in order to discuss the recent scientific advances in relation to vitamin D: the current requirements and associations with various health outcomes. In this article, the discussions resulting from the meeting are summarized.

INTRODUCTION

Several groups at risk for developing vitamin D insufficiency have been identified. Accordingly, reviews indicate that a significant percentage of the population worldwide have serum 25-hydroxyvitamin D levels below 50 nmol/l. In addition to the role of vitamin D in bone health, recent studies suggest that it may play a pivotal role in other systems, e.g., the cardiovascular system, pancreas, muscle, immune system and brain. Most evidence, however, is obtained from observational studies and yet inconclusive.

METHODS

To exchange and broaden knowledge on the requirements for vitamin D and its effect on various health outcomes, a workshop entitled "Vitamin D Expert Meeting: Do we get enough?", was organized.

RESULTS

Despite low vitamin D levels worldwide, consensus on the definition of deficiency is not yet reached. In order to define cut-off points for vitamin D whilst taking into account extraskeletal health effects, randomized controlled trials in these fields are warranted. The experts do emphasize that there is evidence to suggest an important role for vitamin D in the maintenance of optimal bone health at all ages and that vitamin D supplementation, in most studies co-administered with calcium, reduces fracture risk in the senior population.

CONCLUSION

To reach a serum 25-hydroxyvitamin D level of 50 nmol/l older adults aged ≥65 years are therefore recommended to meet a mean daily vitamin D intake of 20 μg (800 IU), which is best achieved with a supplement.

Low bone mass is prevalent in male-to-female transsexual persons before the start of cross-sex hormonal therapy and gonadectomy

OBJECTIVE

Cross-sex hormonal therapy and sex reassignment surgery (including gonadectomy) in transsexual persons has an impact on body composition and bone mass and size. However, it is not clear whether baseline differences in bone and body composition between transsexual persons and controls before cross-sex hormonal therapy play a role.

DESIGN

A cross-sectional study with 25 male-to-female transsexual persons (transsexual women) before cross-gender sex steroid exposure (median age 30 years) in comparison with 25 age-matched control men and a male reference population of 941 men.

MAIN OUTCOME MEASURES

Areal and volumetric bone parameters using respectively dual energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT), body composition (DXA), grip strength (hand dynamometer), Baecke physical activity questionnaire, serum testosterone and 25-OH vitamin D.

RESULTS

Transsexual women before cross-sex hormonal therapy presented with less muscle mass (p≤0.001) and strength (p≤0.05) and a higher prevalence of osteoporosis (16%) with a lower aBMD at the hip, femoral neck, total body (all p<0.001) and lumbar spine (p=0.064) compared with control men. A thinner radial cortex (p≤0.01) and lower cortical area at the radius and tibia (both p<0.05) was found in transsexual women vs. control men. Serum testosterone was comparable in all 3 groups, but 25-OH vitamin D was lower in transsexual women (p≤0.001).

CONCLUSIONS

Transsexual women before the start of hormonal therapy appear to have lower muscle mass and strength and lower bone mass compared with control men. These baseline differences in bone mass might be related to a less active lifestyle.

Correlation of vitamin D, bone mineral density and parathyroid hormone levels in adults with low bone density

BACKGROUND

Bone mineral densiy (BMD) is known to be affected by serum 25-hydroxyvitamin D (25(OH) D) levels, intact parathyroid hormone (iPTH) levels. Indian data pertinent to above observation is scant. Our study aimed to investigate the relationships between serum 25-hydroxyvitamin D (25(OH) D) levels, intact parathyroid hormone (iPTH) levels and bone mineral density (BMD) in a cohort of Indian patients.

MATERIALS AND METHODS

Adults with or without fragility fractures with low BMD at the hip or lumbar spine were evaluated clinically along with laboratory investigations. T-scores of the hip and spine were derived from BMD-DEXA (dual-energy X-ray absorptiometry). Multivariate regression models were used to investigate the relationships between serum 25(OH) D, iPTH and BMD.

RESULTS

Total of 102 patients (male:female = 38:64) with a mean age of 62.5 ± 6.4 years were included in the study. Forty-four patients had osteopenia. Osteoporosis was present in 58 patients. The mean values for serum 25(OH) D and iPTH levels were 21.3 ± 0.5 ng/ml and 53.1 ± 22.3 pg/ml, respectively. In 84.3% of patients, serum 25(OH) D levels were below 30 ng/ml (Normal = 30-74 ng/ml), confirming vitamin D deficiency. There was no association between 25(OH) D levels and BMD at the hip or lumbar spine (P = 0.473 and 0.353, respectively). Both at the hip and lumbar spine; iPTH levels, male gender, body mass index (BMI) and age were found to be significant predictors of BMD. Patients with higher BMI had significantly lower BMD and T-score. At levels <30 ng/ml, 25(OH) D was negatively associated with iPTH (P = 0.041).

CONCLUSION

Among our cohort of patients with low BMD, no direct relationship between serum 25(OH) D levels and BMD was observed. However, a negative correlation between iPTH and 25(OH) D at serum 25(OH) D concentrations <30 ng/ml. Serum iPTH levels showed a significant negative association with BMD at the hip and lumbar spine. Our findings underscore the critical role of parathyroid hormone in bone metabolism and health.

Prevalence and seasonal variation of hypovitaminosis D and its relationship to bone metabolism in healthy Hungarian men over 50 years of age: the HunMen Study

This study reports a high prevalence of hypovitaminosis D and low bone mineral density (BMD) in a healthy Hungarian male cohort over 50 years of age. Men with 25-hydroxyvitamin D levels of <75 nmol/L had a significantly higher 10-year hip and major osteoporotic fracture probability using the country-specific fracture risk assessment (FRAX) algorithm.

INTRODUCTION

The aim of this study is to characterize the prevalence and seasonal variation of hypovitaminosis D and its relationship to bone metabolism in healthy Hungarian men over 50 years of age.

METHODS

We determined levels of 25-hydroxyvitamin D (25-OH-D), PTH, osteocalcin (OC), C-terminal telopeptides of type-I collagen (CTX-I), procollagen type 1 amino-terminal propeptide (PINP), BMD at L1-L4 (LS) and femur neck (FN), daily dietary calcium intake, and the 10-year probability of hip fracture and a major osteoporotic fracture using the country-specific FRAX algorithm in 206 randomly selected ambulatory men.

RESULTS

The mean (range) age of the volunteers was 60 (51-81) years. The prevalence of hypovitaminosis D (25-OH-D, <75 nmol/L) was 52.9%. The prevalence of low (T-score < -1.0) BMD at the FN and LS was 45% and 35.4%, respectively. The mean (range) FRAX hip fracture and FRAX major osteoporotic fracture was 0.8% (0-9.4%) and 3.8% (1.7-16%), respectively. On comparing the vitamin D sufficient to the insufficient group, there was a statistically significant difference between the FRAX hip fracture and FRAX major osteoporotic fracture indexes. There was significant seasonal variation in the vitamin D levels; the lowest levels were measured in winter and the highest in summer.

CONCLUSIONS

A high prevalence of hypovitaminosis D and low BMD were observed in the studied Hungarian male population. This is the first study reporting higher 10-year hip and major osteoporotic fracture probability using the country-specific FRAX algorithm in individuals with hypovitaminosis D.

Effects of age and serum 25-OH-vitamin D on serum parathyroid hormone levels

CONTEXT

Several studies define optimal serum 25-hydroxyvitamin D (25-OHD) levels based on serum PTH level reaching an asymptote. However, results differ widely, ranging from 25-OHD levels of 12-44 ng/ml: many studies are constrained by small sample size.

OBJECTIVE

The objective of the study was to determine the relationship between serum PTH and 25-OHD levels and age in a very large reference laboratory database.

DESIGN

This was a detailed cross-sectional analysis of 312,962 paired serum PTH and 25-OHD levels measured from July 2010 to June 2011.

RESULTS

Median PTH levels and the proportion of patients (PTH > 65 pg/ml), from 63 successive 25-OHD frequency classes of 5000 patients, provide smooth, exceptionally well-fitted curves (R(2) = 0.994 and R(2) = 0.995, respectively) without discernible inflection points or asymptotes but with striking age dependencies. Serum 25-OHD was below the recent Institute of Medicine sufficiency guidance of 20 ng/ml in 27% (85,000) of the subjects. More importantly, 40 and 51% of subjects (serum 25-OHD <20 and 10 ng/ml, respectively) had biochemical hyperparathyroidism (PTH > 65 pg/ml).

CONCLUSIONS

This analysis, despite inevitable inherent limitations, introduces several clinical implications. First, median 25-OHD-dependent PTH levels revealed no threshold above which increasing 25-OHD fails to further suppress PTH. Second, the large number of subjects with 25-OHD deficiency and hyperparathyroidism reinforces the Third International Workshop on Asymptomatic Primary Hyper parathyroidism's recommendations to test for, and replete, vitamin D depletion before considering parathyroidectomy. Third, strong age dependency of the PTH-25-OHD relationship likely reflects the composite effects of age-related decline in calcium absorption and renal function. Finally, this unselected large population database study could guide clinical management of patients based on an age-dependent, PTH-25-OHD continuum.

Vitamin D nutritional status of women living on a solitary island in Japan: A population-based study

OBJECTIVE

Serum 25-hydroxyvitamin D [25(OH)D] is a vitamin D metabolite and a good indicator of vitamin D nutritional status. Low 25(OH)D levels accelerate age-related bone loss in women. The aim of this study was to assess 25(OH)D levels using population-based samples from women in a community in Japan.

SUBJECTS AND METHODS

Of all 187 adult women living on a solitary island (Niigata, Japan), 150 (80.2%) were enrolled in a cross-sectional study in early June 1998. After excluding 6 subjects who were undergoing treatment for osteoporosis, 144 female subjects were analyzed. Serum 25(OH)D(2) and 25(OH)D(3) were determined by high-performance liquid chromatography. The sum of 25(OH)D(2) and 25(OH)D(3) was calculated, yielding 25(OH)D, for which a concentration of less than 30 nmol/L was defined as vitamin D insufficiency. Demographic data such as age, height, weight, and body mass index (BMI) were also recorded.

RESULTS

The average age of the subjects was 61.3 years (SD 12.8), ranging from 21 to 87. The average concentrations of 25(OH)D(2) and 25(OH)D(3) were 0.5 nmol/L (SD 3.2) and 64.6 nmol/L (SD 17.6), respectively. The number of subjects with 25(OH)D concentration less than 30 nmol/L was 4 of 149 (2.7%). Serum 25(OH)D concentrations were not significantly correlated with age (r=-0.065, p=0.44l) or BMI (r=0.086, p=0.310).

CONCLUSION

The present population-based study confirms adequate levels of 25(OH)D and low prevalence of vitamin D insufficiency in Japanese women. Further research should be directed toward darifying which dietary factors determine vitamin D nutrition.

Efficacy of optimization of vitamin D in preventing osteoporosis and osteoporotic fractures: A systematic review

Increased intake or supplementation of vitamin D is often recommended for normal bone health; however, its preventive effect on osteoporosis has not been fully evaluated. The aim of this review is to gather evidence of the efficacy of the optimization of vitamin D nutrition in preventing osteoporosis and osteoporotic fractures. PubMed was used for searching the relevant literature using the MeSH terms "Bone Density (limited to "human", "female", and "English" literature)" or "Fractures (limited to "human", "age ≥45 years", and "English" literature)", and "Vitamin D". The searches yielded 19 randomized controlled trials (RCTs), nine cohort studies, 19 case-control studies, 19 cross-sectional studies, and one meta-analysis. We attempted to answer three questions: 1) does increased vitamin D intake prevent bone loss in peri- and postmenopausal women?, 2) does increased vitamin D intake prevent osteoporotic fractures in the elderly?, and 3) does increased vitamin D in take positively affect peak bone mass attainment in young women? The answer to questions 1 and 2 is that a vitamin D intake of 10-17.5 μg/day (400-700 IU/day) or more is effective in preventing bone loss in late postmenopausal women and an intake of 17.5-20 μg/day (700-800 IU/day) or more together with a calcium supplement reduces the risk of osteoporotic fractures. For question 3, some lines of evidence support the negative effect of low vitamin D nutrition on the attainment of peak bone mass in young women. Further studies are needed to clarify the effect of vitamin D in this age group.

Osteoporosis in children and young adults: a late effect after chemotherapy for bone sarcoma

BACKGROUND

Premature bone loss after childhood chemotherapy may be underestimated in patients with bone sarcoma. Methotrexate (MTX), a standard agent in osteosarcoma protocols, reportedly reduces bone mineral density (BMD). The literature, however, has reported cases of BMD reduction in patients with Ewing's sarcoma treated without MTX. Thus, it is unclear whether osteoporosis after chemotherapy relates to MTX or to other factors.

QUESTIONS/PURPOSES

We therefore asked whether (1) young patients with a bone sarcoma had BMD reduction, (2) patients treated with MTX had lower BMD, and (3) other factors (eg, lactose intolerance or vitamin D deficiency) posed additional risks for low BMD.

METHODS

We retrospectively reviewed 43 patients with malignancies who had dual-energy x-ray absorptiometry (DEXA) (lumbar, femoral); 18 with Ewing's sarcoma (mean age, 26 ± 8 years), and 25 with an osteosarcoma (mean age, 27 ± 10 years). The mean time since diagnosis was 8 ± 4 years in the group with Ewing's sarcoma and 7 ± 5 years in the group with osteosarcoma. At last followup we determined BMD (computing z-scores), fracture rate, and lifestyle, and performed serum analysis.

RESULTS

BMD reduction was present in 58% of patients (37% had a z-score between -1 and -2 SD, 21% had a z-score less than -2 SD) in at least one measured site. Seven of the 43 patients (16%) had nontrauma or tumor-associated fractures after chemotherapy. Findings were similar in the Ewing and osteosarcoma subgroups. We found vitamin D deficiency in 38 patients (88%) and borderline elevated bone metabolism; lactose intolerance was present in 16 patients (37%).

CONCLUSION

Doctors should be aware of the possibility of major bone loss after chemotherapy with a risk of pathologic fracture. Vitamin D deficiency, calcium malnutrition, and lactose intolerance may potentiate the negative effects of chemotherapy, and should be considered in long-term patient management.

LEVEL OF EVIDENCE

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Prevalence of vitamin D insufficiency and low bone mineral density in elderly Thai nursing home residents

Background

Numerous emerging data from research on osteoporosis among Asians found differences from Caucasians. Therefore, the aim of this study was to determine the prevalence of vitamin D insufficiency and osteoporosis in elderly participants from two nursing homes in Thailand, a country located near the equator.

Methods

The subjects of this cross-sectional study comprised 93 elderly Thai women who were living in institutional long-term nursing homes for the aged. Demographic data, daily food and calcium intake, physical activity, and sunlight exposure were measured. Lumbar spine and femoral neck bone mineral density (BMD) and biochemical levels including serum 25 hydroxyvitamin D [25(OH)D] and bone turnover markers were assessed. Vitamin D insufficiency was defined as 25(OH)D level < 70 nmol/l.

Results

The mean age of subjects was 75.2 ± 6.0 (SD) years. Dietary calcium intake was low (322 ± 158 mg/day) The mean 25(OH)D level was 64.3 ± 14.9 nmol/L and the prevalence of vitamin D insufficiency was 38.7% (95% CI: 28.8%, 49.4%). There was no correlation between serum 25(OH)D concentrations and age (r = −.11, p = 0.3). The mean BMD of lumbar spine and femoral neck were 0.92 ± 0.19 and 0.65 ± 0.10 g/cm², respectively. Nearly a half of the subjects had osteopenia (44.1%, 95% CI: 33.8%, 54.8%) and osteoporosis (47.3%, 95% CI: 36.9%, 57.9%). Circulating C-terminal telopeptide of type I collagen (CTx) level correlated significantly with both lumbar spine (r = −0.26, p = 0.01) and femoral neck BMD (r = −0.25, p = 0.02).

Conclusions

More than one-third of Thai elderly women residing in nursing homes had vitamin D insufficiency. Almost all nursing home residents had osteoporosis and/or osteopenia.

The levels of bone turnover markers in Chinese postmenopausal women: Peking Vertebral Fracture study

OBJECTIVE

The aim of this study was to evaluate serum N-aminoterminal propeptide of type I collagen (P1NP), C-terminal telopeptide of type I collagen (β-CTX), and vitamin D status in healthy Chinese postmenopausal women. The study was also designed to investigate their possible relationships with osteoporosis phenotypes.

METHODS

A community-based population of 1,724 postmenopausal women in Beijing was randomly selected. Serum bone turnover markers and 25-hydroxyvitamin D [25(OH)D] were tested by an automated Roche electrochemiluminescence system. Dual-energy x-ray absorptiometry was used to measure bone mineral density (BMD).

RESULTS

The mean (SD) values of serum β-CTX and P1NP were 0.439 (0.210) and 56.7 (27.9) ng/mL, respectively. The 25(OH)D level of postmenopausal women in Beijing was remarkably low (13.2 ± 5.4 ng/mL). Serum β-CTX and P1NP levels were negatively correlated with BMDs of lumbar spine, femoral neck, and total hip (all P < 0.01). The cubic regression model better fitted the relationships of BMD and bone turnover markers. Serum β-CTX levels were significantly higher in women with sustained osteoporotic fracture or vertebral fracture (P = 0.006 and 0.012, respectively). No association between P1NP and fracture or vertebral fracture was detected. The same situation applied to 25(OH)D. 25(OH)D was negatively correlated with β-CTX and P1NP (r = -0.073 and -0.088, P = 0.002 and <0.001, respectively).

CONCLUSIONS

Serum β-CTX and P1NP levels were negatively correlated with BMD. β-CTX was significantly higher in postmenopausal women with sustained fracture or vertebral fracture. Vitamin D deficiency was highly prevalent in postmenopausal women in Beijing.

High prevalence of vitamin D deficiency among healthy Saudi Arabian men: relationship to bone mineral density, parathyroid hormone, bone turnover markers, and lifestyle factors

SUMMARY

In this cross-sectional study, the prevalence of vitamin D deficiency [serum 25-hydroxyvitamin D (25(OH)D) <50 nmol/L] was 87.8% among Saudi Arabian men. There was a linear inverse relationship between serum 25(OH)D and intact parathyroid hormone (PTH) levels, but without a threshold of 25(OH)D at which intact PTH values plateaued.

INTRODUCTION

Vitamin D insufficiency and/or deficiency has now reached epidemic proportions and has been linked to low bone mineral density (BMD), some lifestyle factors, and obesity in adults. This relationship is not well documented in Saudi Arabian men. This study examines the relationship between vitamin D status, intact parathyroid hormone (intact PTH), and lifestyle factors among Saudi Arabian men.

METHODS

This cross-sectional study involved 834 men aged 20-74 years living in Jeddah area who were randomly selected and medically examined. Men had their BMD (lumbar spine (L1-L4) and neck femur), 25(OH)D, intact PTH, and other parameters measured according to detailed inclusion criteria.

RESULTS

Deficiency (25(OH)D<50 nmol/L) and insufficiency (≥50-75 nmol/L) were present in 87.8% and 9.7%, respectively. Deficiency was common among older and obese men with no education and sedentary lifestyle sampled during summer and spring. Serum 25(OH)D showed an inverse linear relationship with intact PTH, but there was no threshold of serum 25(OH)D at which PTH levels plateaued. There was a positive correlation between BMD values at both lumbar spine (L1-L4) (P < 0.023) and neck femur (P < 0.036) and serum 25(OH)D levels, respectively.

CONCLUSIONS

Functionally significant vitamin D deficiency affects BMD and bone turnover markers among Saudi Arabian men and is largely attributed to older age, obesity, sedentary lifestyle, no education, poor exposure to sunlight, smoking, and poor dietary vitamin D supplementation. The data suggest that an increase in PTH cannot be used as a marker for vitamin D deficiency.

Influence of bone remodelling rate on quantitative ultrasound parameters at the calcaneus and DXA BMDa of the hip and spine in middle-aged and elderly European men: the European Male Ageing Study (EMAS)

OBJECTIVE

To assess the influence of sex hormones on markers of bone turnover and to explore the association between these markers and bone health in middle-aged and elderly European men.

DESIGN

A cross-sectional population-based survey.

METHODS

Men aged 40-79 years were recruited from population registers in eight European centres. Subjects completed a postal questionnaire which included questions concerning lifestyle and were invited to undergo quantitative ultrasound (QUS) of the calcaneus and to provide a fasting blood sample from which the bone markers serum N-terminal propeptide of type 1 procollagen (P1NP) and crosslinks (β C-terminal cross-linked telopeptide (β-cTX)), total testosterone, total oestradiol (E(2)), sex hormone-binding globulin (SHBG) and insulin-like growth factor 1 (IGF1) were measured. Dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine was performed in two centres.

RESULTS

A total of 3120, mean age 59.9 years (s.d.=11.0) were included. After adjustment for centre, age, height, weight, lifestyle factors, season and other hormones, total and free E(2) were negatively associated with β-cTX but not P1NP while SHBG, IGF1 and parathyroid hormone (PTH) were positively associated with both β-cTX and P1NP. Total or free testosterone was not independently associated with either bone marker. After the same adjustments, higher levels of both bone markers were significantly associated with lower QUS parameters and lower DXA-assessed bone density at the total hip and lumbar spine.

CONCLUSIONS

E(2), SHBG, IGF1 and PTH contribute significantly to the regulation/rate of bone turnover in middle-aged and older European men. Higher rates of bone remodelling are negatively associated with male bone health.

A systematic review and meta-regression analysis of the vitamin D intake–serum 25-hydroxyvitamin D relationship to inform European recommendations

The present study used a systematic review approach to identify relevant randomised control trials (RCT) with vitamin D and then apply meta-regression to explore the most appropriate model of the vitamin D intake–serum 25-hydroxyvitamin D (25(OH)D) relationship to underpin setting reference intake values. Methods included an updated structured search on Ovid MEDLINE; rigorous inclusion/exclusion criteria; data extraction; and meta-regression (using different model constructs). In particular, priority was given to data from winter-based RCT performed at latitudes >49·5°N (n12). A combined weighted linear model meta-regression analyses of natural log (Ln) total vitamin D intake (i.e. diet and supplemental vitamin D)v. achieved serum 25(OH)D in winter (that used by the North American Dietary Reference Intake Committee) produced a curvilinear relationship (mean (95 % lower CI) serum 25(OH)D (nmol/l) = 9·2 (8·5) Ln (total vitamin D)). Use of non-transformed total vitamin D intake data (maximum 1400 IU/d; 35 μg/d) provided for a more linear relationship (mean serum 25(OH)D (nmol/l) = 0·044 × (total vitamin D)+33·035). Although inputting an intake of 600 IU/d (i.e. the RDA) into the 95 % lower CI curvilinear and linear models predicted a serum 25(OH)D of 54·4 and 55·2 nmol/l, respectively, the total vitamin D intake that would achieve 50 (and 40) nmol/l serum 25(OH)D was 359 (111) and 480 (260) IU/d, respectively. Inclusion of 95 % range in the model to account for inter-individual variability increased the predicted intake of vitamin D needed to maintain serum 25(OH)D ≥ 50 nmol/l to 930 IU/d. The model used to describe the vitamin D intake–status relationship needs to be considered carefully when setting new reference intake values in the Europe.

Women with insufficient 25-hydroxyvitamin D without secondary hyperparathyroidism have altered bone turnover and greater incidence of vertebral fractures

BACKGROUND

The connection of 25-hydroxyvitamin D [25(OH)D] with bone metabolism is reported to occur indirectly through parathyroid hormone (PTH) activity. However, we hypothesized that 25(OH)D insufficiency raises the risk of bone fracture independent of PTH, since 25(OH)D insufficiency is not always accompanied by hyperparathyroidism. The aim of this study was to show a direct association between 25(OH)D, bone turnover markers, and fractures that was independent of PTH.

METHODS

We measured serum 25(OH)D in a group of 330 postmenopausal osteoporotic women who did not have secondary hyperparathyroidism. We analyzed the effects of 25(OH)D insufficiency [25(OH)D < 20 ng/mL] on the expression of several bone markers, including serum bone alkaline phosphatase (BAP), osteocalcin (OC), urinary N-terminal telopeptide of type-I collagen and free deoxypyridinoline (DPD), and inorganic phosphorus (IP), as well as on the prevalence of vertebral fractures.

RESULTS

OC/BAP ratios and IP levels were significantly lower and DPD was significantly higher in 25(OH)D insufficient patients. These effects were independent of age, PTH, and estimated glomerular filtration rate (eGFR). 25(OH)D insufficiency, a low OC/BAP ratio, and low IP were related to the presence of prior vertebral fractures independent of PTH, bone mineral density (BMD), and eGFR.

CONCLUSIONS

We propose that 25(OH)D insufficiency is associated with a low OC/BAP ratio and high DPD in postmenopausal osteoporosis patients without hyperparathyroidism. This pathological condition is associated with an increased incidence of prior vertebral fractures independent of PTH, BMD, and eGFR.

Nanoparticles based on hydrophobic alginate derivative as nutraceutical delivery vehicle: vitamin D3 loading

We report the application of Vitamin D3 (VD(3)) in nanoparticles of oleoyl alginate ester (OAE)(OAE-VD(3)). The internalization of fluorescent OAE-VD(3) by Caco-2 cells was visualized by confocal laser scanning microscopy. In vivo pharmacokinetic studies showed that incorporation into OAE nanoparticles resulted in increased absorption of VD(3). Its application in the treatment of rickets was assayed using a model of nutritionally induced vitamin D-deficiency rickets. The results showed that the encapsulated VD(3) had better efficacy than that of the free drug in vivo. Our studies provide evidence that OAE nanoparticles are valuable as nutraceutical delivery vehicles to enhance the absorption of VD(3).

Making sense of the latest advice on vitamin D therapy

The Institute of Medicine recently published recommendations for the daily intake and optimal serum levels of vitamin D based on an extensive review of the existing literature. Here we examine the issue and put levels of vitamin D in context for the general population and in patients with chronic kidney disease. Large randomized controlled trials are necessary to ensure that current recommendations are appropriate.

Role of parathyroid hormone in bone fragility of postmenopausal women with vitamin D insufficiency

Vitamin D insufficiency is related to an increase in PTH, which might be critical for an increase in bone fragility. However, the role of endogenous PTH in vitamin D insufficiency-induced fracture risk remains unclear. The present study was performed to examine the relationships among vitamin D insufficiency, bone fragility, and PTH in 202 Japanese postmenopausal women. Serum 25-hydroxyvitamin D (25[OH]D) levels were measured. The percentages of subjects with 25(OH)D levels below 10, 15, and 20 ng/ml were 5.0, 41.0, and 80.7%, respectively. Serum 25(OH)D levels were negatively related to age and serum levels of Cr and PTH; they were positively related to bone mineral density (BMD). In multiple regression analysis, BMD was significantly related to 25(OH)D levels when adjusted for age, body mass index (BMI), and serum levels of Cr and PTH. Multiple logistic regression analysis showed that lower 25(OH)D levels were significantly related to prevalent fracture risk when adjusted for age, BMI, serum levels of Cr and PTH, as well as femoral neck BMD. The proportion of subjects with prevalent fractures was significantly higher in the group with lower PTH and lower 25(OH)D than in the group with lower PTH and higher 25(OH)D or higher PTH and higher 25(OH)D. In conclusion, vitamin D insufficiency was found to be related to prevalent fracture risk independently of PTH. Functional hypoparathyroidism, rather than functional hyperparathyroidism, might be a risk factor for bone fragility in vitamin D insufficiency.

Relationship between vitamin D, parathyroid hormone, and bone health

CONTEXT

There is a controversy regarding the definition of vitamin D insufficiency as it relates to bone health.

OBJECTIVE

The objective of the study was to examine the evidence for a threshold value of serum 25-hydroxyvitamin D (25OHD) that defines vitamin D insufficiency as it relates to bone health.

DESIGN AND PARTICIPANTS

This was a cross-sectional analysis of baseline data in 488 elderly Caucasian women, mean age 71 yr, combined with a literature review of 70 studies on the relationship of serum PTH to serum 25OHD.

SETTING

The study was conducted in independent-living women in the midwest United States.

MAIN OUTCOME MEASURE

The relationship between serum 25OHD, serum PTH, and serum osteocalcin and 24-h urine N-telopeptides was evaluated.

RESULTS

Serum PTH was inversely correlated with serum 25OHD (r = -0.256, P < 0.0005), but no threshold as defined by suppression of serum PTH was found within the serum 25OHD range 6-60 ng/ml (15-150 nmol/liter). However, in contrast, there was a threshold for bone markers, serum osteocalcin and urine N-telopeptides, that increased only below a serum 25OHD of approximately 18 ng/ml (45 nmol/liter). Calcium absorption was not correlated with serum PTH and serum 25OHD, and no threshold was found. A literature review of 70 studies generally showed a threshold for serum PTH with increasing serum 25OHD, but there was no consistency in the threshold level of serum 25OHD that varied from 10 to 50 ng/ml (25-125 nmol/liter).

CONCLUSIONS

Vitamin D insufficiency should be defined as serum 25OHD less than 20 ng/ml (50 nmol/liter) as it relates to bone.