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.     

Impact of vitamin D supplementation on markers of bone mineral metabolism in term infants

25-Hydroxyvitamin D (25OHD) may influence bone turnover. We compared the dynamics of bone markers in 30 infants on vitamin D supplementation (? 550 IU/day) with different degrees of hypovitaminosis D (25OHD < 11 ng/ml — deficiency vs. ≥ 11 < 20 ng/ml — insufficiency). Baseline and follow-up (after 10 weeks), 25OHD, 1,25-dihydroxyvitamin D (1,25(OH)₂D), alkaline phosphatase (ALP), PTH, osteocalcin (OC), N-terminal propeptide of type I procollagen (PINP), C-terminal telopeptide of type I collagen (CTX), and amino-terminal propeptide of C-type natriuretic peptide (NT-proCNP) were measured. None of the newborns had craniotabes, hypocalcemia or hyperparathyroidism. The median (Q1;Q3) 25OHD increased from a baseline of 8.45 (7;11.9) ng/ml to 54.6 (34.7;67.3) ng/ml (p < 0.001). The baseline 25OHD negatively correlated with total increment of 25OHD (r = ? 0.54; p = 0.002). There were changes in ALP (241 vs. 331 IU; p < 0.001), 1,25(OH)₂D (48 vs. 95.5 pg/ml, p < 0.001), OC (88.8 vs. 159.1 ng/ml, p < 0.001), PINP (3886 vs. 2409 ng/ml; p < 0.001), CTX (1.6 vs. 1.1 ng/ml; p < 0.001), and NT-proCNP (75.1 vs. 35.1 pmol/l; p < 0.001). Vitamin D deficient infants at baseline, compared to the insufficient group, revealed significantly higher percentage changes for 25OHD (745% vs. 167%, p < 0.0001), OC (113% vs. 40%, p < 0.05) and 1,25(OH)₂D (95% vs. 58%, p < 0.05). Conclusions: Vitamin D supplements had little to no impact on markers of bone turnover in term infants in the first few months of life, with the exception of osteocalcin. Ten weeks of cholecalciferol supplementation at a dose of 550 IU/day led to a marked increase of 25OHD concentration. The magnitude of 25OHD increment was inversely related to vitamin D status at baseline. Irrespective of the severity of vitamin D deficiency, a secondary hyperparathyroidism with elevated iPTH, ALP, phosphaturia or hypophosphatemia was not observed in the studied neonates.     

Vitamin D inadequacy in French osteoporotic and osteopenic women

ObjectiveStudies have shown that low serum vitamin D levels are associated with secondary hyperparathyroidism, which decreases bone strength and increases fracture risk, most notably after 50 years of age. The objective of this study was to evaluate the vitamin D status of postmenopausal women in France.MethodsWe conducted a cross-sectional observational study of 1292 menopausal women with osteoporosis or osteopenia. The age range was 52–94 years. Serum 25-OH-vitamin D was assayed in each patient. Based on data in the literature, we used four 25-OH-D cutoffs to define vitamin D deficiency: 30, 50, 75, and 80 nmol/L (<12, <20, <30, and <32 ng/ml).ResultsMean serum 25-OH-D was 51.5 ± 26.1 nmol/L (about 20.6 ± 10.4 ng/ml). In the 343 (26.5%) patients taking supplemental vitamin D with or without supplemental calcium, the mean serum 25-OH-D level was significantly higher than in the other patients (65.0 ± 26.0 ng/ml vs. 46.6 ± 18.6 ng/ml; P < 0.001). In the subgroup not taking vitamin D supplements, the prevalence of vitamin D deficiency was 27.3%, 54.1%, 89.9%, and 93.2% with the 30, 50, 75, and 80 nmol/L cutoffs, respectively. The mean 25-OH-D level varied across seasons (P < 0.001), with the highest value being obtained in summer (53.4 ± 18.7 nmol/L; about 21.3 ± 7.5 ng/ml).ConclusionVitamin D deficiency is common among postmenopausal women with osteoporosis or osteopenia in France.     

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.     

High-dose oral vitamin D3 supplementation in rheumatology patients with severe vitamin D3 deficiency

ObjectivesRecent large trials indicate that adherence associated with a daily regimen of vitamin D is low and limits anti-fracture efficacy with vitamin D supplementation. The aim of this report is to describe changes of 25-hydroxyvitamin D (25(OH)D) serum concentrations achieved with a single oral dose of 300 000 IU vitamin D3.MethodsOver a course of 4 months, we identified 33 elderly with severe vitamin D deficiency (25(OH)D < 25 nmol/l) on admission to acute care. Patients were admitted for musculoskeletal pain, bone disease, or gait abnormalities. The mean age was 80.5 years (SD ± 6.1). All patients were treated with a single oral dose of 300 000 IU D3 in combination with 500–1000 mg calcium supplements per day depending on their dietary calcium intake.ResultsBaseline mean 25(OH)D serum concentrations were 15 nmol/l (SD ± 5.5). Mean 25(OH)D serum concentrations increased to 81.4 nmol/l (SD ± 29.7) at 3 months (29 patients) and were still 69.0 nmol/l (SD ± 17.9) at 6 months (26 patients). Mean serum calcium levels were 2.24 mmol/l (SD ± 0.11) at baseline, 2.28 mmol/l (SD ± 0.18) at 3 months, and 2.28 mmol/l (SD ± 0.13) at 6 months. Two patients with mild hypercalcemia (2.69 mmol/l) at 3 months had normal values at 6 months.ConclusionBased on our observations, a single oral dose of 300 000 IU vitamin D3 raises mean 25(OH)D serum concentrations to the target mean of above 75 nmol/l at 3 months and a mean level of 69 nmol/l at 6 months. As calcium absorption is enhanced with higher 25(OH)D serum concentrations, calcium supplementation may need downward adjustment with this regimen to avoid mild hypercalcemia.     

Effect of high-dose vitamin D supplementation on bone density in youth with osteogenesis imperfecta: A randomized controlled trial

Osteogenesis imperfecta (OI) is a heritable condition characterized by fragile bones. Our previous studies indicated that serum 25-hydroxyvitamin D (25OHD) concentrations were positively associated with lumbar spine areal bone mineral density (LS-aBMD) in children and adolescents with OI. Here we assessed whether one year of high-dose vitamin D supplementation results in higher LS-aBMD z-scores in youth with OI. A one-year double-blind randomized controlled trial conducted at a pediatric orthopedic hospital in Montreal, Canada. Sixty patients (age: 6.0 to 18.9 years; 35 female) were randomized in equal numbers to receive either 400 or 2000 international units (IU) of vitamin D, stratified according to baseline bisphosphonate treatment status and pubertal stage. At baseline, the average serum 25OHD concentration was 65.6 nmol/L (SD 20.4) with no difference between treatment groups (p = 0.77); 21% of patients had results < 50 nmol/L. Vitamin D supplementation was associated with higher serum 25OHD concentrations in 90% of participants. The increase in mean 25OHD was significantly higher (p = 0.02) in the group receiving 2000 IU of vitamin D (mean [95% CI] = 30.5 nmol/L [21.3; 39.6]) than in the group receiving 400 IU (15.2 nmol/L [6.4; 24.1]). No significant differences in LS-aBMD z-score changes were detected between treatment groups. Thus, supplementation with vitamin D at 2000 IU increased serum 25OHD concentrations in children with OI more than supplementation with 400 IU. However, in this study where about 80% of participants had baseline serum 25OHD concentrations ≥ 50 nmol/L, this difference had no detectable effect on LS-aBMD z-scores.     

25 hydroxyvitamin D serum levels influence adequate response to bisphosphonate treatment in postmenopausal osteoporosis

It remains unclear whether vitamin D sufficiency optimizes response to bisphosphonate (BP) treatment in postmenopausal osteoporosis. We evaluated the role and possible mechanisms of vitamin D in adequate response to standard BP treatment for postmenopausal osteoporosis.MethodsWe included 120 postmenopausal osteoporotic women (aged 68 ± 8 years) receiving BP (alendronate or risedronate) at their annual follow-up, performing complete anamnesis, including treatment adherence, use of vitamin D supplements, and previous falls and fractures during the last year. We analyzed the evolution of bone mineral density (BMD) during this period and serum PTH and 25 hydroxyvitamin D (25(OH)D) and urinary NTx levels. Patients were classified as inadequate responders to antiosteoporotic treatment based on BMD loss > 2% and/or the presence of fragility fractures during the last year.ResultsThirty percent of patients showed inadequate response to BP treatment, with significantly lower levels of 25(OH)D (22.4 ± 1.3 vs. 26.6 ± 0.3 ng/ml, p = 0.01), a higher frequency of 25(OH)D levels < 30 ng/ml (91% vs. 69%, p = 0.019) and higher urinary NTx values (42.2 ± 3.9 vs. 30.9 ± 2.3 nM/mM, p = 0.01). Patients with 25(OH)D > 30 ng/ml had a greater significant increase in lumbar BMD than women with values < 30 ng/ml (3.6% vs. 0.8%, p < 0.05). The probability of inadequate response was 4-fold higher in patients with 25(OH)D < 30 (OR, 4.42; 95% CI, 1.22–15.97, p = 0.02).ConclusionsInadequate response to BP treatment is frequent in postmenopausal women with osteoporosis as is vitamin D insufficiency, despite vitamin D supplementation. Maintenance of 25(OH)D levels > 30 ng/ml is especially indicated for adequate response to BP treatment.     

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.     

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.     

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.     

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.     

Pharmacokinetics of oral vitamin D3 and calcifediol

AimLong-term pharmacokinetics after supplementation with vitamin D₃ or calcifediol (the 25-hydroxyvitamin D₃ metabolite) is not well studied. Additionally, it is unclear whether bolus doses of vitamin D₃ or calcifediol lead to 25(OH)D₃ plasma concentrations considered desirable for fracture prevention (30 ng/mL). We therefore investigated plasma pharmacokinetics of 25(OH)D₃ during different vitamin D₃ and calcifediol supplementation regimens.MethodsIn this seven-arm, randomized, double-blind, controlled parallel-group study, 35 healthy females aged 50–70 years (5 per group) received 20 μg calcifediol or vitaminD₃ daily, 140 μg calcifediol or vitaminD₃ weekly, for 15 weeks, or a single bolus of either 140 μg calcifediol, or vitaminD₃, or both. 25(OH)D₃ plasma concentrations were quantified using LC–MS/MS in 14 clinical visits among all participants.ResultsFor daily (weekly) dosing, the area under the concentration–time curve (AUC_0–24h), which is the measure for exposure, was 28% (67%) higher after the first dose of calcifediol than after the first dose of vitamin D₃. After 15 weeks, this difference was 123% (178%). All women in the daily and weekly calcifediol groups achieved 25(OH)D₃ concentrations > 30 ng/mL (mean, 16.8 days), but only 70% in the vitamin D₃ daily or weekly groups reached this concentration (mean, 68.4 days). A single dose of 140 μg calcifediol led to 117% higher 25(OH)D₃ AUC_0–96h values than 140 μg vitamin D₃, while the simultaneous intake of both did not further increase exposure.ConclusionsCalcifediol given daily, weekly, or as a single bolus is about 2–3 times more potent in increasing plasma 25(OH)D₃ concentrations than vitamin D₃. Plasma 25(OH)D₃ concentrations of 30 ng/mL were reached more rapidly and reliably with calcifediol.     

25-Hydroxyvitamin D Measurement, 2009: A Review for Clinicians

As clinicians are more widely appreciating the endemic nature of low vitamin D status, measurement of serum 25-hydroxyvitamin D (25(OH)D), the accepted measure of vitamin D status, has increased. Challenges to 25(OH)D measurement include the presence of 2 forms of vitamin D—ergocalciferol and cholecalciferol (vitamin D₂ and vitamin D₃, respectively)— and the hydrophobic nature of vitamin D. The current state of 25(OH)D measurement is reviewed; modest differences between methodologies persist and confound the application of a single cut point (e.g., 30 ng/mL/75 nmol/L) for the diagnosis of low vitamin D status. The absence of standard calibrators contributes to between-laboratory differences in 25(OH)D measurement. Until there is improved assay standardization and subsequent evidence-based consensus, it seems premature to recommend widespread screening 25(OH)D measurement. Selectively obtaining 25(OH)D measurement in individuals at clinical risk for vitamin D deficiency and/or those most likely to promptly experience benefits from supplementation seems appropriate.     

Hypovitaminosis D and Bone Mineral Metabolism and Bone Density in Hyperthyroidism

Little is known about the impact of concomitant vitamin D deficiency on bone mineral density in hyperthyroidism. Therefore, we evaluated bone mineral measures in vitamin D–deficient and sufficient patients with hyperthyroidism. Thirty newly diagnosed consecutive patients with hyperthyroidism were included. Blood samples were used for measurement of calcium, phosphate, alkaline phosphatase, 25-hydroxy vitamin D [25(OH) D], and parathyroid hormone (PTH). Bone mineral density (BMD) was measured at the hip, spine, and forearm. The patients were divided into vitamin D–deficient (<25 nmol/L) and vitamin D–sufficient groups (≥25 nmol/L). Eight (26.6%) patients had 25(OH) D levels less than 25 nmol/L, with mean ± standard deviation (SD) level of 16.5 ± 3.2 (vitamin D–deficient group 1), and the remainder had a mean ± SD of 46.0 ± 13.5 nmol/L (vitamin D–sufficient group 2). Serum-intact PTH levels were significantly higher in group 1 compared with those in group 2 (31.2 ± 16.3 vs 18.0 ± 13.1 pg/mL; p = 0.041). In the vitamin D–deficient group, the mean BMD T-scores were in the osteoporotic range at hip and forearm (?2.65 ± 1.13 and ?3.04 ± 1.3) and in the osteopenia range at lumbar spine (?1.83 ± 1.71). However, in vitamin D–sufficient group, the mean BMD T-scores were in the osteopenia range (?1.64 ± 1.0, ?1.27 ± 1.6, and ?1.60 ± 0.7) at hip, forearm, and lumbar spine, respectively. The mean BMD Z-scores were also significantly lower in vitamin D–deficient group compared with those in vitamin D–sufficient group. Finally, BMD values (gm/cm²) at the hip and forearm were significantly lower in the vitamin D–deficient group compared with those in the vitamin D–sufficient group. In conclusion, hyperthyroid patients with concomitant vitamin D deficiency had lower BMD compared with vitamin D–sufficient patients.     

Establishment of TBS reference plots and correlation between TBS and BMD in healthy mainland Chinese women

Summary

Vitamin D deficiency was highly prevalent in this study. More than half of the participants with vitamin D level less than 5 ng/mL had secondary hyperparathyroidism, which implicated a major bone health concern. After adjustment for potential predictors, parathyroid hormone (PTH) explained about 3 % of the variance in total hip bone mineral density (BMD).

Purpose

Bone mineral density (BMD) is known to be influenced by serum 25-hydroxyvitamin D (25OHD) and intact parathyroid hormone (PTH) levels. The relationship between 25OHD and PTH with BMD has not been well documented in Syrian adults. We aimed to determine how differences in serum 25OHD and PTH levels impacted hip and lumbar spine BMD among apparently healthy Syrian adults.

Methods

25OHD and PTH were measured in 156 participants aged 18–53 years from Damascus and its surroundings. Lumbar spine and hip BMD measurements were measured by dual-energy X-ray absorptiometry using Hologic Discovery Wi densitometer. Multivariate regression models were used to investigate the relationships between 25OHD, PTH, and BMD.

Results

All participants, except one male, had 25OHD <30 ng/mL (<75 nmol/L), and 89.1 % of them had 25OHD levels less than 20 ng/mL (50 nmol/L). Secondary hyperparathyroidism was significantly more prevalent in the lowest 25OHD quartile compared to that in the highest quartile (59 vs. 10.3 %, p < 0.0001). Mean bone mineral density at all sites in our participants was lower when compared to that of their Caucasian counterparts in Europe and North America. No significant correlation was found between 25OHD and BMD either at hip or at lumbar spine. In the multivariate analyses, after adjustment for potential predictors, PTH explained about 3 % of the variation in total hip BMD.

Conclusions

Low BMD was relatively frequent at all measured sites. PTH, but not 25OHD, was a predictor for total hip BMD in a young population.

     

Transient effectiveness of vitamin D2 therapy in pediatric cystic fibrosis patients

BackgroundThe effectiveness of current treatment recommendations for vitamin D insufficiency in children with CF is unknown. Therefore, we assessed the effectiveness of vitamin D₂ 50,000 IU once daily for 28 days for vitamin D insufficiency.MethodsRetrospective chart review of pediatric CF patients from 2006–2008. Vitamin D₂ 50,000 IU daily for 28 days was given to patients with 25-OHD < 30 ng/mL and repeat 25-OHD levels were obtained after completion of therapy.ResultsOne hundred forty-seven levels from 97 individuals were assessed. Success of treatment was 54% (n = 80/147). Seventeen of 39 patients (43%) followed for an additional 6–18 months were able to maintain levels of ≥ 30 ng/mL.ConclusionsVitamin D₂ 50,000 IU daily for 28 days was effective in correcting vitamin D insufficiency in approximately 50% of subjects. However, almost half of successfully treated patients were unable to maintain normal 25-OHD levels > 6 months after completion of therapy, implying that this effect is transient.     

Vitamin D Supplementation in Young White and African American Women

There is limited information on the effects of vitamin D on serum 25 hydroxyvitamin D (25OHD) in young people and none on African Americans. The main objective of this trial was to measure the effect of different doses of vitamin D3 on serum 25OHD and serum parathyroid hormone (PTH) in young women with vitamin D insufficiency (serum 25OHD ≤ 20 ng/mL (50 nmol/L). A randomized double‐blind placebo‐controlled trial of vitamin D3 was conducted in young white and African American women, age 25 to 45 years. A total of 198 healthy white (60%) and African American (40%) women were randomly assigned to placebo, or to 400, 800, 1600, or 2400 IU of vitamin D3 daily. Calcium supplements were added to maintain a total calcium intake of 1000 to 1200 mg daily. The primary outcomes of the study were the final serum 25OHD and PTH levels at 12 months. The absolute increase in serum 25OHD with 400, 800, 1600, and 2400 IU of vitamin D daily was slightly greater in African American women than in white women. On the highest dose of 2400 IU/d, the mixed model predicted that mean 25OHD increased from baseline 12.4 ng/mL (95% confidence interval [CI], 9.2–15.7) to 43.2 ng/mL (95% CI, 38.2–48.1) in African American women and from 15.0 ng/mL (95% CI, 12.3–17.6) to 39.1 ng/mL (95% CI, 36.2–42.0) in white women. There was no significant effect of vitamin D dose on serum PTH in either race but there was a significant inverse relationship between final serum PTH and serum 25OHD. Serum 25OHD exceeded 20 ng/mL in 97.5% of whites on the 400 IU/d dose and between 800 and 1600 IU/d for African Americans. The recommended dietary allowance (RDA) suggested by the Institute of Medicine for young people is 600 IU daily. The increase in serum 25OHD after vitamin D supplementation was similar in young and old, and in white and African American women. © 2014 American Society for Bone and Mineral Research.     

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.