Hypovitaminosis D osteopathy: is it mediated through PTH, lean mass, or is it a direct effect?

Effects of PTH and PTH Hypersecretion on Bone: a Clinical Perspective

PURPOSE OF REVIEW

Hyperparathyroidism may be due to an autonomous hypersecretion of parathyroid hormone (PTH) or occurs in response to a number of physiological stimuli. A number of recent findings have provided new insights into the importance of the calcium-parathyroid-vitamin D axis to bone in normal physiology and pathological conditions.

RECENT FINDINGS

PTH is known to affect bone microarchitecture with different effects on cortical and trabecular bone compartments. In trabecular bone, PTH may exert anabolic effects, whereas PTH promotes bone resorption in cortical bone. Vertebral fractures are prevalent in primary hyperparathyroidism (PHPT), and patients seem to fracture at higher values of bone mineral density (BMD) than patients with osteoporosis. This may be explained by changes in bone microarchitecture, which cannot be detected by measuring BMD. Even in mild PHPT, bone seems to benefit from parathyroidectomy. In secondary hyperparathyroidism, bone seems much more susceptible to fracture with insufficient levels of vitamin D compared with a replete vitamin status. If elevated PTH levels cannot be explained by conditions known to cause secondary hyperparathyroidism, the condition is termed normocalcemic PHPT, which also has been associated with an increased risk of fractures. Hyperparathyroidism is harmful to bone, which is why it is of importance to normalize PTH levels either by parathyroidectomy in PHPT or by counteracting conditions known to increase PTH in secondary hyperparathyroidism.

Impact of Calcium and Two Doses of Vitamin D on Bone Metabolism in the Elderly: A Randomized Controlled Trial

The optimal dose of vitamin D to optimize bone metabolism in the elderly is unclear. We tested the hypothesis that vitamin D, at a dose higher than recommended by the Institute of Medicine (IOM), has a beneficial effect on bone remodeling and mass. In this double-blind trial we randomized 257 overweight elderly subjects to receive 1000 mg of elemental calcium citrate/day, and the daily equivalent of 3750 IU/day or 600 IU/day of vitamin D3 for 1 year. The subjects' mean age was 71 ± 4 years, body mass index 30 ± 4 kg/m² , 55% were women, and 222 completed the 12-month follow-up. Mean serum 25 hydroxyvitamin D (25OHD) was 20 ng/mL, and rose to 26 ng/mL in the low-dose arm, and 36 ng/mL in the high-dose arm, at 1 year (p < 0.05). Plasma parathyroid hormone, osteocalcin, and C-terminal telopeptide (Cross Laps) levels decreased significantly by 20% to 22% in both arms, but there were no differences between the two groups for any variable, at 6 or 12 months, with the exception of serum calcitriol, which was higher in the high-dose group at 12 months. Bone mineral density (BMD) increased significantly at the total hip and lumbar spine, but not the femoral neck, in both study arms, whereas subtotal body BMD increased in the high-dose group only, at 1 year. However, there were no significant differences in percent change BMD between the two study arms at any skeletal site. Subjects with serum 25OHD <20 ng/mL and PTH level >76 pg/mL showed a trend for higher BMD increments at all skeletal sites, in the high-dose group, that reached significance at the hip. Adverse events were comparable in the two study arms. This controlled trial shows little additional benefit in vitamin D supplementation at a dose exceeding the IOM recommendation of 600 IU/day on BMD and bone markers, in overweight elderly individuals. © 2017 American Society for Bone and Mineral Research.

No Associations of 25-Hydroxycholecalciferol and Parathyroid Hormone Concentrations with Calcaneal Bone Characteristics in Community-Dwelling Elderly Subjects: A Cross-Sectional Study

OBJECTIVE

This study examined the associations of 25-hydroxycholecalciferol [25(OH)D3] and intact parathyroid hormone (iPTH) concentrations with bone status parameters in elderly subjects.

DESIGN/SETTING

Cross-sectional data based on the follow-up 2008 of the longitudinal study on nutrition and health status of senior citizens in Giessen, Germany.

PARTICIPANTS

One hundred eighty-eight independently living subjects aged 66-96 years.

MEASUREMENTS

Serum concentrations of 25(OH)D3, iPTH, N-terminal propeptide of type 1 collagen (P1NP) and activity of alkaline phosphatase (ALP) were assessed. Broadband ultrasound attenuation, speed of sound and stiffness index were determined by calcaneal quantitative ultrasound (QUS). Multiple linear regression analyses were performed to analyse associations of 25(OH)D3 and iPTH with bone status parameters.

RESULTS

Median (range) 25(OH)D3 and iPTH concentrations were 62.8 (29.9-106.7) nmol/L and 4.6 (1.3-21.0) pmol/L, respectively. Neither 25(OH)D3 nor iPTH was associated with calcaneal bone characteristics measured by QUS, whereas negative associations between 25(OH)D3 and bone formation markers (P1NP and ALP) were found. In a sub analysis, 25(OH)D3 was negatively associated with ALP only in subjects with iPTH concentrations > 4.59 pmol/L.

CONCLUSION

The present study provides no evidence for independent associations of 25(OH)D3 and iPTH with calcaneal bone characteristics in community-dwelling elderly subjects with 25(OH)D3 concentrations between 30 and 107 nmol/L. However, 25(OH)D3 interacts with bone formation markers, particularly in subjects with high iPTH concentrations.

Serum 25-hydroxyvitamin D and bone turnover markers in Palestinian postmenopausal osteoporosis and normal women

This study evaluated the association of vitamin D and bone markers with the development osteoporosis in Palestinian postmenopausal women. Even though vitamin D deficiency was very high for the recruited subjects, it was not associated with osteoporosis except for bones of the hip. Age and obesity were the strongest determining factors of the disease.

PURPOSE

The purpose of this study was to investigate the association of bone mineral density (BMD) with serum vitamin D levels, parathyroid hormone (PTH), calcium, obesity, and bone turnover markers in Palestinian postmenopausal women.

METHODS

Three hundred eighty-two postmenopausal women (≥45 years) were recruited from various women clinics for BMD assessment (131 women had osteoporosis and 251 were normal and served as controls). Blood samples were obtained for serum calcium, PTH, 25(OH)D, bone formation (N-terminal propeptide (PINP)), and bone resorption (serum C-terminal telopeptide of type I collagen (CTX1)) markers.

RESULTS

Women with osteoporosis had statistically significant lower mean weight, height, body mass index (BMI), and serum calcium (p < 0.05) compared to controls. No significant differences were detected between the mean values of bone turnover markers (CTX and PINP), 25(OH)D, and PTH of the two groups. Women with vitamin D deficiency (severe and insufficiency) represented 85.9% of the study subjects. Multiple and logistic regression showed that age and BMI significantly affected BMD and vitamin D had a significant association with BMD only at the lumbar spine. BMI was positively correlated with BMD and PTH but negatively correlated with vitamin D. Logistic regression showed that the odds ratio (OR) for having osteoporosis decreased with increasing BMI (overweight OR = 0.11, p = 0.053; obese OR = 0.05, p = 0.007).

CONCLUSIONS

There was no direct correlation between BMD and PTH, bone turnover markers, and vitamin D except at the lumbar spine. A negative correlation between BMD and age and a positive correlation with BMI were observed. The protective effect of obesity on osteoporosis was complicated by the effect of obesity on vitamin D and PTH.

Hypovitaminosis D Among Patients Admitted With Hip Fracture to a Level-1 Trauma Center in the Sunny Upper Egypt: Prevalence and Associated Correlates

INTRODUCTION

Despite abundant sunshine, hypovitaminosis D is common in the Middle East. The aim of this study was to determine the prevalence of hypovitaminosis D and related correlates among patients with hip fracture in Assiut University Hospitals in Upper Egypt.

MATERIALS AND METHODS

A cross-sectional study was carried out in 133 patients with hip fracture, aged 50 years and older, admitted to Trauma Unit of Assiut University Hospitals, from January through December 2014. Patients were selected by systematic random sampling. Serum 25-hydroxy vitamin D level was measured by enzyme-linked immunosorbent assay; bone mineral density (BMD) by dual-energy X-ray absorptiometry. Weight and height measurements were used for body mass index (BMI) calculation.

RESULTS

Patients' median age was 70 years (range: 50-99); 51.9% were females. Osteoporosis (femoral neck T score: <-2.5 standard deviation) prevalence was 72.2%. Of all patients, 60.9% had vitamin D deficiency (<20 ng/mL); 15.8% reported vitamin D inadequacy (from 20 to 29 ng/mL) and vitamin D levels were normal in 23.3% (>30 ng/mL). According to univariate analysis, vitamin D deficiency was significantly associated with obesity (P = .012) and low T scores of the femoral neck (P = .001), L2 (P = .021), L3 (P = .031), L4 (P = .012), and the greater trochanter (P < .001). In a multivariable logistic regression model, high BMI and low BMD of the femoral neck and greater trochanter were associated with hypovitaminosis D.

CONCLUSION

Prevalence of hypovitaminosis D is high among patients with hip fracture and associated with low BMD and high BMI. Increasing awareness about prevention as well as detection and treatment of vitamin D deficiency is recommended.

The association between vitamin D and parathyroid hormone and bone mineral density: the Dong-gu Study

The primary objective of the present study was to investigate the relationship between 25-hydroxyvitamin D (25[OH]D) and areal bone mineral density (aBMD) in Korean subjects from the general population aged ≥50 years. This study included 8,857 individuals who completed the baseline survey of the Dong-gu study, which was conducted in Korea from 2007-2010. The participants who fulfilled the detailed inclusion criteria underwent assessment of the femoral neck and lumbar spine aBMD as well as measurement of serum 25(OH)D and parathyroid hormone (PTH) levels. After adjusting for other covariates and log-PTH values, the mean aBMD of the femoral neck exhibited a significant increase with increasing 25(OH)D levels in both males (p < 0.001) and females (p = 0.005). Additionally, the mean aBMD of the lumbar spine exhibited a significant increase with increasing 25(OH)D levels in males (p = 0.011) but not females (p = 0.252). After adjusting for covariates and log-25(OH)D values, the mean aBMD values of the femoral neck and lumbar spine showed significant decreases with increasing PTH levels in both males and females (p < 0.001). The present findings demonstrate that the aBMD of the femoral neck was significantly associated with 25(OH)D levels independent of PTH in both males and females and that the aBMD of the lumbar spine was significantly associated with 25(OH)D levels independent of PTH in males, but not females.

Effect of vitamin D replacement on indexes of insulin resistance in overweight elderly individuals: a randomized controlled trial

BACKGROUND

It is unclear whether and at what dose vitamin D supplementation affects insulin resistance (IR).

OBJECTIVE

We sought to investigate whether vitamin D at doses higher than currently recommended decreases indexes of IR in an ambulatory population of overweight elderly subjects.

DESIGN

This double-blind, randomized, controlled multicenter trial enrolled 257 elderly overweight individuals aged ≥65 y with baseline 25-hydroxyvitamin D [25(OH)D] concentrations between 10 and 30 ng/mL. All subjects received 1000 mg calcium citrate/d, with vitamin D administered weekly at an equivalent dose of 600 or 3750 IU/d. The homeostasis model assessment (HOMA) of IR index at 1 y was the primary outcome. We also assessed the McAuley index.

RESULTS

In total, 222 subjects (55% women) with a mean ± SD age and body mass index (BMI; in kg/m(2)) of 71 ± 4 y and 30 ± 4, respectively, completed the study. Subjects' baseline characteristics, including IR indexes, were similar across groups: 69% had prediabetes, 54% had hypertension (47% were taking antihypertensive medications), and 60% had hyperlipidemia, nearly half of whom were receiving lipid-lowering drugs. At 1 y, mean ± SD serum 25(OH)D increased from 20 ± 7 to 26 ± 7 ng/mL in the low-dose arm (P < 0.0001) and from 21 ± 8 to 36 ± 10 ng/mL in the high-dose arm (P < 0.001). Median HOMA-IR indexes did not change compared with baseline concentrations and were similar in the high- [2.2 (IQR: 1.5, 2.9)] and low-dose [2.3 (IQR: 1.6, 3.3] treatment groups. Adjusted analyses showed that HOMA-IR was predicted by the baseline HOMA index and BMI but not by vitamin D dose, baseline serum 25(OH)D, or change in 25(OH)D.

CONCLUSION

Vitamin D3 at 3750 IU/d did not improve HOMA-IR compared with the Institute of Medicine Recommended Dietary Allowance of 600 IU/d in elderly overweight individuals. This trial was registered at clinicaltrials.gov as NCT01315366.

Osteoporosis: An under-recognized public health problem

Over 200 million people suffer from osteoporosis worldwide, which occurs when bone tissues become structurally deteriorated and bone mass becomes fragile, resulting in an increased risk of fracture. This review aims to describe the underlying risk factors and provide guidance on changes in lifestyle for those at risk of developing osteoporosis. It highlights risk factors such as age, sex, genetic background, and other under lying illnesses (factors that are generally “non-modifiable”). Furthermore, it focuses on factors that are dependent on lifestyle and (local) habits (factors that are “modifiable”), such as diet, sunlight exposure, exercise, and medication. Clearly, osteoporosis is a multifactorial disease and multiple of these risk factors can occur simultaneously. Currently, the data available differ greatly between regions and some areas might be affected more seriously than others. This review suggests that this might be due to differing healthcare training systems and suboptimal awareness of osteoporosis. Importantly, osteoporosis and resulting bone fractures represent a significant economic burden for both individuals and the wider society. Therefore, improved awareness of the disease may influence personal habits, reduce suffering, and alleviate the burden on healthcare expenditure.

Differences in the prevalence of vitamin D deficiency and hip fractures in nursing home residents and independently living elderly

OBJECTIVE

To compare the prevalence of vitamin D deficiency and fracture history in nursing home residents and community-dwelling elderly subjects and to explore the association of vitamin D levels with various characteristics.

MATERIALS AND METHODS

Sixty-six nursing home residents and 139 community-dwelling elderly subjects participated. Marital status, medical history, medication including vitamin D supplements, smoking, past fractures were assessed. Weight and height were measured and body mass index calculated. Serum 25-hydroxyvitamin D (25-OHD), PTH, Ca, phosphate, creatinine and eGFR were determined.

RESULTS

In the nursing home residents 25-OHD was lower (17.8 nmol/l, [9.4-28.6] vs. 36.7 nmol/l, [26.9-50], p < 0.001), PTH was higher (5.6 pmol/l, [3.9-8.9] vs. 4.7 pmol/l [3.6-5.8], P = 0.003) and 25-OHD deficiency was more prevalent (65.2% [53.7-76.7] vs. 22.3% [15.4-29.2], p < 0.001) as was elevated PTH (23% [12.8-33] vs. 5.8% [2-10], p = 0.001). 25-OHD correlated negatively with PTH (institutionalized r = -0.28, p = 0.025 and community-dwelling r = -0.36, p < 0.001). Hip fractures were reported by 8% of the residents and 2% of the independent elderly. The only predictor for hip fracture was elevated PTH (OR = 7.6 (1.5-36.9), p = 0.013).

CONCLUSION

The prevalence of vitamin D deficiency and secondary hyperparathyroidism was high in the institutionalized subjects. Hip fracture risk was associated with elevated PTH and not directly with vitamin D levels or the residency status.

Serum 25-hydroxyvitamin D predicts cognitive performance in adults

BACKGROUND

Vitamin D is an endogenous hormone known to regulate calcium levels in the body and plays a role in cognitive performance. Studies have shown an association between vitamin D deficiency and cognitive impairment in older adults. Lebanon has a high 25-hydroxyvitamin D (25(OH)D) deficiency prevalence across all age groups.

METHODS

In this cross-sectional study, we explored the cognitive performance and serum 25(OH)D levels using an electrochemoluminescent immunoassay in 254 older (>60 years) as well as younger (30-60 years) adults. Subjects' characteristics, including age, years of education, wearing of veil, alcohol consumption, smoking, and physical exercise, were collected. Participants were screened for depression prior to cognitive screening using the Montreal Cognitive Assessment Arabic version. Visuospatial memory was tested using the Rey Complex Figure Test and Recognition Trial, and speed of processing was assessed using the Symbol Digit Modalities test.

RESULTS

Pearson's correlation and stepwise linear regression analyses showed that a low vitamin D level was associated with greater risk of cognitive impairment in older as well as younger adults.

CONCLUSION

These findings suggest that correction of vitamin D needs to be explored as an intervention to prevent cognitive impairment. Prospective longitudinal studies are needed to ascertain the effect of such interventions.

Femoral volumetric bone density, geometry, and strength in relation to 25-hydroxy vitamin D in older men

Low serum 25-hydroxy vitamin D (25(OH)D) concentrations are associated with increased hip fracture risk and decreased femoral areal bone mineral density (BMD) among elderly men. Structural dimensions of the proximal femur and volumetric BMD in cortical and trabecular compartments are also associated with hip fracture risk. However, associations of volumetric BMD or structural dimensions with serum 25(OH)D concentrations among older men remain unclear. In a random sample of 1608 men aged ≥65 years from the Osteoporotic Fractures in Men Study (MrOS), baseline serum 25(OH)D concentrations were measured by liquid chromatography/mass spectrometry assays. Femoral neck geometry and volumetric BMD derived from quantitative computed tomography included integral, cortical, and trabecular volumetric BMD; cross-sectional area; integral and cortical volume; and cortical volume as a percent of integral volume. We studied 888 men with vitamin D, parathyroid hormone (PTH), femoral neck geometry, and BMD measures. Whole-bone femoral strength and load-strength ratio from finite element (FE) analysis were also available for 356 men from this sample. Multivariable linear regression was used to estimate least square means of each femoral measure within quartiles of 25(OH)D adjusted for age, race, body mass index, height, latitude, and season of blood draw. Tests of linear trend in the means were performed across increasing quartile of serum 25(OH)D levels. Mean cortical volume (p trend = 0.006) and cortical volume as a percent of integral volume (p trend < 0.001) increased across increasing quartile of 25(OH)D level. However, overall femoral neck size (area and integral volume) did not vary by 25(OH)D level. Femoral neck volumetric BMD measures increased in a graded manner with higher 25(OH)D levels (p trend < 0.001). Femoral strength, but not load-strength ratio, increased with increasing 25(OH)D. Adjustment for PTH did not materially change these associations. We conclude that in older men, higher levels of endogenous 25(OH)D may increase whole-bone strength by increasing femoral volumetric BMD and cortical volume.

Hypovitaminosis D in the Middle East and North Africa: Prevalence, risk factors and impact on outcomes

BACKGROUND

The Middle East and North Africa (MENA) region registers some of the highest rates of hypovitaminosis D worldwide.  

AIM

We systematically reviewed the prevalence of hypovitaminosis D, rickets and osteomalacia, their predictors and impact on major outcomes, in the region.

METHODS

Medline, Pubmed and Embase search engines, entering keywords and concepts, combined with individual countries of interest, were used. Search was limited years 2000-2012; and review articles were used for the period preceding year 2000.

RESULTS

Rickets and osteomalacia still occur in this sunny region. Hypovitaminosis D prevails, with rates varying 30-90%, considering a desirable serum 25 hydroxy-vitamin D [25(OH)D] of 20 ng/ml. Advancing age, female gender, multi-parity, clothing style, season, socio-economic status and urban living are recognized predictors of hypovitaminosis D in adults. Prolonged breastfeeding without vitamin D supplementation and low dietary calcium intake are the recognized risk factors for rickets and hypovitaminosis D in children.. Associations with pain score and disease activity in rheumatologic disorders, viral load and interleukins in hepatitis C, BMI, lipids and insulin sensitivity, blood pressure, heart failure and mortality are described. Sun exposure in adults decreased prevalence of metabolic syndrome in one study. Few randomized vitamin D trials revealed that the majority of mothers or children failed to achieve a desirable 25(OH)D level, even with doses by far exceeding current recommendations. A trial in adolescent girls reveals substantial bone and lean mass increments.

CONCLUSION

Hypovitaminosis D is prevalent in MENA. The lack of populations based studies, gaps in studies in infants, pre-pubertal children and pregnant women, hinder the development of region specific guidelines and constitute a major obstacle to impact this chronic and most often subclinical disease.

Vitamin D deficiency is a problem for adult out-patients? A university hospital sample in Istanbul, Turkey

OBJECTIVE

To investigate the frequency of vitamin D deficiency in relation to demographics, clinical diagnosis, season of measurement and laboratory parameters in adult out-patients.

DESIGN

Descriptive, retrospective study concerning evaluation of the initial 25-hydroxyvitamin D (25(OH)D) levels determined at admission in relation to demographics, clinical diagnosis, season of measurement and laboratory parameters. 25(OH)D levels ,20 ng/ml were classified as deficiency, 20–30 ng/ml as insufficiency and .30 ng/ml as sufficiency.

SETTING

Out-patient clinics at a tertiary care centre.

SUBJECTS

A total of 2488 adult patients (mean age: 53?3 (SD 15?2) years; 85?2% were females) admitted to out-patient clinics at Baskent University Istanbul Hospital were included.

RESULTS

Mean level of 25(OH)D in the overall population was 17?4 (SD 11?5) ng/ml while insufficiency and deficiency were evident in 24% and 66% of patients, respectively. Mean 25(OH)D levels in males .45 years old were higher than in their female counterparts (19?4 (SD 11?3) ng/ml v. 17?8 (SD 12?2) ng/ml; P,0?05). Mean 25(OH)D levels obtained in summer (18?6 (SD 11?1) ng/ml) and autumn (23?3 (SD 13?6) ng/ml) were significantly higher than levels in spring (16?1 (SD 10?3) ng/ml) and winter (14?6 (SD 10?2) ng/ml; P,0?01). Mean 25(OH)D levels were determined to be significantly lower in obese patients compared with non-obese patients (15?6 (SD 10?4) ng/ml v. 17?6 (SD 11?6) ng/ml; P,0?05). Levels of 25(OH)D were significantly negatively correlated with serum parathyroid hormone levels (r520?194; P,0?001) while significantly positively correlated with phosphorus (r50?059; P,0?01) and HDL cholesterol (r50?070; P,0?01) levels.

CONCLUSIONS

Our findings indicate that vitamin D deficiency is very common among out-patients in Turkey, regardless of gender and age, especially among obese people and during winter and spring.

Relationship between vitamin D, parathyroid hormone, and bone mineral density in elderly Koreans

There is controversy regarding definition of vitamin D inadequacy. We analyzed threshold 25-hydroxyvitamin D (25[OH]D) below which intact parathyroid hormone (iPTH) increases, and examined age- and sex-specific changes of 25(OH)D and iPTH, and association of 25(OH)D and iPTH with bone mineral density (BMD) in elderly Koreans. Anthropometric parameters, serum 25(OH)D and iPTH, lumbar spine and femur BMD by dual-energy radiography absorptiometry (DXA) were measured in 441 men and 598 postmenopausal women. iPTH increased below serum 25(OH) of 36.7 ng/mL in men, but failed to reach plateau in women. Femur neck BMD above and below threshold differed when threshold 25(OH)D concentrations were set at 15-27.5 ng/mL in men, and 12.5-20 ng/mL in postmenopausal women. Vitamin D-inadequate individuals older than 75 yr had higher iPTH than those aged ≤ 65 yr. In winter, age-associated iPTH increase in women was steeper than in summer. In conclusion, vitamin D inadequacy threshold cannot be estimated based on iPTH alone, and but other factors concerning bone health should also be considered. Older people seemingly need higher 25(OH)D levels to offset age-associated hyperparathyroidism. Elderly vitamin D-inadequate women in the winter are most vulnerable to age-associated hyperparathyroidism.

Hypovitaminosis D as a risk factor of subsequent vertebral fractures after kyphoplasty

BACKGROUND CONTEXT

Over the past 20 years, methods of minimally invasive surgery have been developed for the treatment of vertebral compression fractures. Balloon kyphoplasty and vertebroplasty are associated with a recurrent fracture risk in the adjacent levels after the surgical procedure. In certain patient categories with impaired bone metabolism, the risk of subsequent fractures after kyphoplasty is increased.

PURPOSE

To determine the incidence of recurrent fractures after kyphoplasty and explore whether the status of bone metabolism and 25-hydroxyvitamin D (25(OH)D) levels affect the occurrence of these fractures.

STUDY DESIGN

Prospective longitudinal clinical study.

PATIENT SAMPLE

Forty female postmenopausal women with primary osteoporosis and acute symptomatic vertebral compression fractures.

OUTCOME MEASURES

Identification of new vertebral fractures and documentation of indicators of bone metabolism.

METHODS

A total of ninety-eight kyphoplasties were performed in 40 female patients. Balloon kyphoplasty was performed on all symptomatic acute vertebral compression fractures. Age, body mass index, history of tobacco use, number of initial vertebral fractures, intradiscal cement leakage, history of nonspinal fractures, use of antiosteoporotic medications, bone mineral density, bone turnover markers, and 25(OH)D levels were assessed. All participants were evaluated clinically and/or radiographically. Follow-up period was 18 months.

RESULTS

The mean population age was 70.6 years (range, 40-83 years). After initial kyphoplasty procedure, nine patients (11 levels) (22.5% of patients; 11.2% of levels) developed a postkyphoplasty vertebral compression fracture. Cement leakage was identified in seven patients (17.5%). The patients without recurrent fractures after kyphoplasty demonstrated higher levels of 25(OH)D (22.6±5.51 vs. 14.39±7.47; p=.001) and lower N-terminal cross-linked telopeptide values (17.11±10.20 vs. 12.90±4.05; p=.067) compared with the patients with recurrent fractures.

CONCLUSIONS

Bone metabolism and 25(OH)D levels seem to play a role in the occurrence of postkyphoplasty recurrent vertebral compression fractures.

PTH level but not 25 (OH) vitamin D level predicts bone loss rates in the elderly

We assessed the impact of calciotropic hormones on bone loss in 195 elderly subjects. After a median follow up of 4 years, parathyroid hormone (PTH) correlated negatively with changes in bone mineral density (BMD) at all skeletal sites. After adjustment for potential predictors of bone loss in the elderly, PTH level alone explained 3% of the variance in BMD changes at the hip.

INTRODUCTION

This study assessed the impact of calciotropic hormones on bone loss rates in an elderly population-based cohort of 195 ambulatory men and women, aged 65-85 years and followed up for a median of 4 years.

METHODS

Calcium intake, serum calcium, and phosphorus were assessed at baseline. Serum creatinine was measured at follow up visit. The 25 (OH) vitamin D [25-OHD] and PTH were measured at baseline and at follow up. Bone mass at the lumbar spine, hip, forearm and total body, as well as body composition was measured at baseline and at follow up by dual energy X-ray absorptiometry.

RESULTS

Mean 25-OHD level was 14.7 ± 6.4 ng/ml and mean PTH level was 47.9 ± 30.4 pg/ml. Age correlated negatively with percent changes in BMD at all skeletal sites (p < 0.05). Changes in body mass index (BMI) and in body composition correlated positively with BMD changes at all sites, except at the forearm. There was no correlation between 25-OHD and changes in BMD except at the trochanter (r = 0.19, p < 0.008). Conversely, PTH negatively correlated with changes in BMD at all skeletal sites (r = -0.14 to -0.27, p < 0.05). This correlation persisted after adjustment for age, changes in BMI, changes in fat mass and lean mass, serum creatinine, calcium intake, and 25-OHD levels. PTH level alone explained 3% of the variance in BMD changes at all hip subregions.

CONCLUSIONS

Serum PTH, but not 25-OHD, predicted bone loss rates in the elderly. Thus, it is important to normalize PTH level when correcting hypovitaminosis D in the elderly.

25-hydroxyvitamin D assay variations and impact on clinical decision making

CONTEXT

Laboratories are increasingly shifting to new automated 25-hydroxyvitamin D (25-OHD) assays, with subsequent variability in results.

OBJECTIVE/SETTING

We describe the experience at our center with such a shift and illustrate its clinical implications.

METHODS

25-OHD levels were measured in 494 patients using Immunodiagnostic Systems RIA (IDS-RIA) and DiaSorin Liaison assays. Sources of variability between the assays were investigated in a subset of 83 samples, retested in the reference laboratory in the United States, and by reviewing the performance reports issued by the International Vitamin D External Quality Assessment Scheme, DEQAS. 25-OHD cut-points for target levels were used to compare the two assays.

RESULTS

25-OHD concentrations were significantly lower when measured with Liaison as compared to IDS-RIA: mean bias was -5 ng/ml, range was -38.1 to 18.7 ng/ml, P<0.001; the absolute bias was independent of 25-OHD value. Interassay variability was also detected in values obtained in the reference laboratory and in DEQAS reports. Using 20 ng/ml as the target 25-OHD level, 52% of patients required treatment when tested by Liaison, as opposed to 36% by IDS-RIA (P<0.001). Using 30 ng/ml as the desirable level, the proportions were 79 and 64%, respectively (P<0.001). The two assays agreed in only 41-68% of subjects, proportions that depended on criteria used to define agreement.

CONCLUSION

A change in 25-OHD assays has a significant impact on results, patient classification, and treatment recommendations. Such variability cannot be ignored when deriving and applying vitamin D guidelines. It also renders universal assay standardization a pressing call.

Serum 25-hydroxyvitamin D concentration and physical function in adult men

OBJECTIVE

Recent reports suggest that vitamin D status influences musculoskeletal health; yet, there are limited data in adult men. This study investigated whether serum 25-hydroxyvitamin D [25(OH)D] concentration was associated with lean body mass, muscle strength and physical performance in men.

DESIGN

Population-based, observational survey.

PARTICIPANTS

1219 black, Hispanic and white randomly selected men aged 30-79 years from the Boston Area Community Health/Bone Survey.

MEASUREMENTS

Lean body mass by dual-energy X-ray absorptiometry, hand grip strength, a composite physical function score (chair stand and walking speed), 25(OH)D, parathyroid hormone (PTH), testosterone, age, race, body mass index, socioeconomic status, education, smoking, arthritis, self-reported health, calcium intake, physical activity.

RESULTS

The distributions of serum 25(OH)D quartiles differed by race/ethnicity, education and smoking status. After adjustment for multiple lifestyle factors, serum 25(OH)D was not related to lean body mass, grip strength or the composite physical function score (all P>0.20). There was no variation in the associations between 25(OH)D level and outcomes by race/ethnicity. The relationship between PTH and the outcomes revealed similar results.

CONCLUSION

In this population-based sample of adult men with a broad age range, there was no association between serum 25(OH)D concentration and lean body mass, muscle strength and physical function after controlling for multiple lifestyle factors.

Vitamin D status in relation to obesity, bone mineral density, bone turnover markers and vitamin D receptor genotypes in healthy Saudi pre- and postmenopausal women

The various factors that may contribute to vitamin D deficiency or insufficiency were examined among healthy Saudi pre- and postmenopausal women. Vitamin D deficiency was highly prevalent among studied Saudi women with obesity, poor sunlight exposure, poor dietary vitamin D supplementation and age as the main risk factors.

INTRODUCTION

The various factors that may contribute to vitamin D deficiency or insufficiency in relation to bone health among Saudi women are not known. The main objectives of the present study were to determine the factors influencing vitamin D status in relation to serum 25-hydroxyvitamin D (25(OH)D), intact parathyroid hormone (PTH), bone turnover markers (BTMs), bone mineral density (BMD), and vitamin D receptor genotype (VDR) in healthy Saudi pre- and postmenopausal women.

METHODS

A total number of 1,172 healthy Saudi women living in the Jeddah area were randomly selected and studied. Anthropometric parameters, socioeconomic status, sun exposure index together with serum levels of 25(OH)D, calcitriol, intact PTH, Ca, PO4, Mg, creatinine, albumin, and biochemical BTMs were measured. BMD was measured by a dual energy X-ray absorptiometry and VDR genotypes were also determined.

RESULTS

About 80.0% of Saudi women studied exhibited vitamin D deficiency (serum 25(OH)D<50.0 nmol/L) with only 11.8% of all women were considered with adequate vitamin D status (serum 25(OH)D>75 nmol/L). Secondary hyperparathyroidism was evident in 18.5% and 24.6% in pre- and postmenopausal women with 25(OH)D<50 nmol/L. Serum 25(OH)D was lower (P<0.001) and intact PTH higher (P<0.001) in the upper quintiles of body mass index (BMI) and waist-to-hip ratio (WHR). Multiple linear regression analysis showed that BMI, sun exposure index, poor dietary vitamin D supplementation, WHR, and age were independent positive predictors of serum 25(OH)D values.

CONCLUSIONS

Vitamin D deficiency is highly prevalent among healthy Saudi pre-and postmenopausal women and largely attributed to obesity, poor exposure to sunlight, poor dietary vitamin D supplementation, and age.

Hypovitaminosis D in developing countries-prevalence, risk factors and outcomes

Hypovitaminosis D is a prevalent disorder in developing countries. Clinical manifestations of hypovitaminosis D include musculoskeletal disorders, such as nonspecific muscle pain, poor muscle strength and low BMD, as well as nonmusculoskeletal disorders, such as an increased risk of respiratory infections, diabetes mellitus and possibly cardiovascular diseases. In developing countries, the prevalence of hypovitaminosis D varies widely by and within regions; prevalence ranges between 30-90%, according to the cut-off value used within specific regions, and is independent of latitude. A high prevalence of the disorder exists in China and Mongolia, especially in children, of whom up to 50% are reported to have serum 25-hydroxyvitamin D levels <12.5 nmol/l. Despite ample sunshine throughout the year, one-third to one-half of individuals living in Sub-Saharan Africa and the Middle East have serum 25-hydroxyvitamin D levels <25 nmol/l, according to studies published in the past decade. Hypovitaminosis D is also prevalent in children and the elderly living in Latin America. Risk factors for hypovitaminosis D in developing countries are similar to those reported in Western countries and include extremes of age, female sex, winter season, dark skin pigmentation, malnutrition, lack of sun exposure, a covered clothing style and obesity. Clinical trials to assess the effect of vitamin D supplementation on classical and nonclassical clinical outcomes in developing countries are needed.

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

CONTEXT

It is unclear whether the relationship between 25-OHD and PTH is modulated by age or gender.

OBJECTIVE

To assess the 25-OHD-PTH relationship in 340 adolescents (10-17 years) and 443 elderly (65-85 years) of the same ethnic group, and living in the same sunny country.

ASSESSMENTS

Calcium intake was estimated. Serum calcium, phosphorus, 25-OHD and PTH were measured. Body fat was determined by DXA.

RESULTS

25-OHD levels were lower in the elderly in the overall group (p<0.001) and within genders. 25-OHD levels were lower in females in the overall group and within age subgroups (p<0.05). PTH levels were higher in the elderly in the overall population and in both genders (p<0.001). There were no gender differences in PTH levels within age subgroups. For the same 25-OHD level, PTH levels were comparable across genders but were 1.5-2 folds higher in the elderly compared to adolescents (p<0.001). PTH correlated positively with age (p<0.001), body fat (p=0.02), and negatively with calcium intake (p<0.001), and 25-OHD (p<0.001). The magnitude of the correlation with 25-OHD decreased after adjustment for age but not for gender. In multivariate analyses, age, 25-OHD and fat mass were independent predictors for PTH. In the elderly, after adjustment for serum creatinine, only 25-OHD and creatinine were independent predictors of PTH.

CONCLUSION

The negative relationship between 25-OHD and PTH is modulated by age but not gender. Desirable 25-OHD levels derived from examining the 25-OHD-PTH relationship should therefore take into account the age of the population of interest.

Effect of age, gender and calciotropic hormones on the relationship between vitamin D receptor gene polymorphisms and bone mineral density

BACKGROUND/OBJECTIVES

Hypovitaminosis D is a major public health problem worldwide and unexpectedly more so in sunny countries. Vitamin D receptor (VDR) gene is associated with inter-individual variance in bone mineral density (BMD). Studies assessing the effect of VDR gene polymorphisms on BMD yielded conflicting results. The aim of this study was to assess the relationship between VDR polymorphisms and BMD in the Lebanese, across age groups and genders and to assess the effect of PTH and lean mass and vitamin D levels on such relationship.

SUBJECTS/METHODS

In total, 203 subjects aged 65-85 years and 336 children aged 10-17 years. Polymorphisms in the VDR gene were assessed with the restriction enzymes BsmI, TaqI and ApaI. Bone mineral content, BMD and lean mass were measured using Dual-Energy X-ray Absorptiometry (DXA). The dominant hand strength was measured in children.

RESULTS

Heterozygote genotype was the most frequent in both age groups. There was no difference in the frequency distribution of genotypes between the young and the elderly. No relationship between VDR genotypes and lean mass was found in either age group. Heterozygote boys had the lowest parathormone (PTH) and heterozygote elderly women had the highest BMD at the spine and forearm.

CONCLUSIONS

In the Lebanese, the relationship between VDR polymorphisms and BMD differs by age. Survival does not seem to differ by VDR genotype. However, further studies are needed to assess the effect of VDR gene polymorphisms on mortality per se and time to mortality, not evaluated in this study.

Low levels of 25-hydroxyvitamin D in the pediatric populations: prevalence and clinical outcomes

Vitamin D deficiency is becoming increasingly common in the USA. In this review we provide estimates of the prevalence of deficiency, and review the risk factors and the evidence of clinical consequences of vitamin D deficiency. Vitamin D deficiency causes the pediatric disease rickets. In addition, there is some evidence that vitamin D deficiency may lead to other diseases including diabetes mellitus, hypertension, infections, asthma and dyslipidemia.

Serum 25-hydroxyvitamin D is related to indicators of overall physical fitness in healthy postmenopausal women

OBJECTIVE

Inadequate vitamin D status is related to increased adiposity, risk of falls, and muscle weakness, particularly in older people. We hypothesized that serum 25-hydroxyvitamin D [25(OH)D] is related to physical fitness indices (androidal fat, whole body lean mass, balance, strength) in healthy postmenopausal women.

METHODS

Covariates for fitness indices included age or years since menopause, weight, 25(OH)D, energy expenditure, and calcium intake. Overall and regional (androidal fat mass = waist + hip fat) body composition was assessed (N = 242) via dual-energy x-ray absorptiometry.

RESULTS

Regression analyses revealed that 71% of variability (P <or= 0.0001) in androidal fat mass was accounted for by weight (53.0%, P <or= 0.0001), white blood cell (WBC) count (2.0%, P <or= 0.0001), supplemental calcium (1.7%, P = 0.0004), years since menopause (1.1%, P = 0.0034), 25(OH)D (1.0%, P = 0.0051), and vegetable servings (0.6%, P = 0.027); 64% of variability (P <or= 0.0001) in lean mass was accounted for by weight (63.1.%, P <or= 0.0001), WBC count (1.4%, P = 0.0038), and 25(OH)D (1.0%, P = 0.013); 12% of variability (P <or= 0.0001) in balance (right + left leg) was accounted for by age (3.8%, P = 0.0019), 25(OH)D (2.0%, P = 0.025), and WBC count (1.8%, P = 0.032); 14% of variability (P <or= 0.0001) in handgrip strength (right + left) was accounted for by weight (9.3%, P <or= 0.0001), 25(OH)D (2.4%, P = 0.013), WBC count (2.1%, P = 0.019), and age (1.6%, P = 0.044); and 22% of variability (P <or= 0.0001) in torso strength was accounted for by site (15.0%, P <or= 0.0001) and weight (4.6%, P = 0.0003).

CONCLUSIONS

Serum 25(OH)D was the common contributor to physical fitness indices (androidal fat mass, lean mass, balance, handgrip strength) in healthy postmenopausal women.

Global vitamin D status and determinants of hypovitaminosis D

This review describes the vitamin D status in different regions of the world with the objective of understanding the scope of hypovitaminosis D and the factors related to its prevalence that may contribute to the pathogenesis of osteoporosis and fragility fractures.

INTRODUCTION

Vitamin D status has been linked to the pathogenesis of hip fractures as well as other skeletal and non-skeletal disorders. The purpose of this review is to provide a global perspective of vitamin D status across different regions of the world and to identify the common and significant determinants of hypovitaminosis D.

METHODS

Six regions of the world were reviewed-Asia, Europe, Middle East and Africa, Latin America, North America, and Oceania-through a survey of published literature.

RESULTS

The definition of vitamin D insufficiency and deficiency, as well as assay methodology for 25-hydroxyvitamin D or 25(OH)D, vary between studies. However, serum 25(OH)D levels below 75 nmol/L are prevalent in every region studied whilst levels below 25 nmol/L are most common in regions such as South Asia and the Middle East. Older age, female sex, higher latitude, winter season, darker skin pigmentation, less sunlight exposure, dietary habits, and absence of vitamin D fortification are the main factors that are significantly associated with lower 25(OH)D levels.

CONCLUSION

Reports from across the world indicate that hypovitaminosis D is widespread and is re-emerging as a major health problem globally.

Vitamin D: emerging new roles in insulin sensitivity

The growing incidence of prediabetes and clinical type 2 diabetes, in part characterised by insulin resistance, is a critical health problem with consequent devastating personal and health-care costs. Vitamin D status, assessed by serum 25-hydroxyvitamin D levels, is inversely associated with diabetes in epidemiological studies. Several clinical intervention studies also support that vitamin D, or its active metabolite 1,25-dihydroxyvitamin D (1,25(OH)2D), improves insulin sensitivity, even in subjects with glucose metabolism parameters classified within normal ranges. The mechanisms proposed which may underlie this effect include potential relationships with improvements in lean mass, regulation of insulin release, altered insulin receptor expression and specific effects on insulin action. These actions may be mediated by systemic or local production of 1,25(OH)2D or by suppression of parathyroid hormone, which may function to negatively affect insulin sensitivity. Thus, substantial evidence supports a relationship between vitamin D status and insulin sensitivity; however, the underlying mechanisms require further exploration.

Dietary intervention with vitamin D, calcium, and whey protein reduced fat mass and increased lean mass in rats

The aim of the current study was to determine the effects and the mechanisms of inclusion of dietary whey protein, high calcium, and high vitamin D intake with either a high-sucrose or high-fat base diets on body composition of rodents. Male Wistar rats were assigned to either no whey protein, suboptimal calcium (0.25%), and vitamin D (400 IU/kg) diet (LD), or a diet containing whey protein, high calcium (1.5%), and vitamin D (10 000 IU/kg) diet (HD), and either high-fat (40% of energy) or high-sucrose (60%) base diets for 13 weeks. Liver tissue homogenates were used to determine [(14)C]glucose and [(14)C]palmitate oxidation. mRNA expression of enzymes related to energy metabolism in liver, adipose, and muscle, as well as regulators of muscle mass and insulin receptor was assessed. The results demonstrated that there was reduced accumulation of body fat mass (P = .01) and greater lean mass (P = .03) for the HD- compared to LD-fed group regardless of the background diet. There were no consistent differences between the LD and HD groups across background diets in substrate oxidation and mRNA expression for enzymes measured that regulate energy metabolism, myostatin, or muscle vascular endothelial growth factor. However, there was an increase in insulin receptor mRNA expression in muscle in the HD compared to the LD groups. In conclusion, elevated whey protein, calcium, and vitamin D intake resulted in reduced accumulation of body fat mass and increased lean mass, with a commensurate increase in insulin receptor expression, regardless of the level of calories from fat or sucrose.

First update of the Lebanese guidelines for osteoporosis assessment and treatment

With the demographic explosion, the human, social, and economic costs of osteoporosis in developing countries, including the Middle East, will continue to rise. In 2002, the Lebanese Guidelines for Osteoporosis Assessment and Treatment were developed to optimize quality of osteoporosis care in Lebanon and the region. They were endorsed by 5 Lebanese medical scientific societies, and by the Eastern Mediterranean Regional Office branch of the World Health Organization (WHO). In April 2006, the Lebanese Society for Osteoporosis and Metabolic Bone Disorders (OSTEOS) led an initiative to update several recommendations detailed in the original document, based on relevant new local and international data. Data from a population-based sample of elderly Lebanese validated the following recommendations: fracture risk assessment, expressed as relative risk per standard deviation (RR/SD) decrease, was comparable in Lebanese subjects to similarly derived estimates from Western studies; the use of the NHANES database (hip), and the densitometer American database (spine) was as good, if not superior to the use of a Lebanese database for identifying subjects with prevalent vertebral fractures. The original recommendation regarding the use of a gender-specific western database, densitometer for spine and NHANES for T-score derivation for men, remains unchanged. For skeletal site selection, the update recommends measuring the spine and hip for women < or =65 yr, hip only for subjects >65 yr, and adding the forearm in conditions associated with cortical bone loss or in the case of inability to measure axial sites. The original recommendations for conservative management in premenopausal women were reiterated. This First Update of the Lebanese Osteoporosis Guidelines validates previous recommendations using evidence from a population-based sample of elderly Lebanese, and lays the ground for transitioning the Lebanese Osteoporosis Guidelines to the WHO global fracture risk assessment model.

Relationships of low serum vitamin D3 with anthropometry and markers of the metabolic syndrome and diabetes in overweight and obesity

Low serum 25 hydroxyvitamin D₃ (vitamin D₃) is known to perturb cellular function in many tissues, including the endocrine pancreas, which are involved in obesity and type II diabetes mellitus (TIIDM). Vitamin D₃ insufficiency has been linked to obesity, whether obesity is assessed by body mass index (BMI) or waist circumference (waist). Central obesity, using waist as the surrogate, is associated with the metabolic syndrome (MetSyn), insulin resistance, TIIDM and atherosclerotic cardiovascular disease (CVD). We tested how vitamin D₃ was related to measures of fat mass, MetSyn markers, haemoglobin A_1c (HbA_1c) and MetSyn in a cross-sectional sample of 250 overweight and obese adults of different ethnicities. There were modest inverse associations of vitamin D₃ with body weight (weight) (r = -0.21, p = 0.0009), BMI (r = -0.18, p = 0.005), waist (r = -0.14, p = 0.03), [but not body fat % (r = -0.08, p = 0.24)], and HbA_1c (r = -0.16, p = 0.01). Multivariable regression carried out separately for BMI and waist showed a decrease of 0.74 nmol/L (p = 0.002) in vitamin D₃ per 1 kg/m² increase in BMI and a decrease of 0.29 nmol/L (p = 0.01) per 1 cm increase in waist, with each explaining approximately 3% of the variation in vitamin D₃ over and above gender, age, ethnicity and season.

The similar relationships of BMI and waist with vitamin D₃ may have been due to associations between BMI and waist, or coincidental, where different mechanisms relating hypovitaminosis D₃ to obesity occur concurrently. Previously reviewed mechanisms include that 1) low vitamin D₃, may impair insulin action, glucose metabolism and various other metabolic processes in adipose and lean tissue 2) fat soluble-vitamin D₃ is sequestered in the large adipose compartment, and low in serum, 3) obese people may be sensitive about their body shape, minimising their skin exposure to view and sunlight (not tested). We showed evidence for the first theory but no evidence to support the second.

In the current study, serum vitamin D₃ was inversely related to weight, BMI and markers of TIIDM (large waist, raised HbA_1c) but not to adipose mass nor to MetSyn per se.

The effect of menopause on bone mineral density and bone-related biochemical variables in Indonesian women

OBJECTIVE

To determine the effects of menopause on bone-related variables in Indonesian women and to compare them with corresponding data in Caucasian Australian women.

DESIGN

A study of bone-related variables in women aged 45-55 years in Jakarta compared with corresponding historical data from Caucasian Australian women.

MEASUREMENTS

Dietary intakes, bone mineral density (BMD) and calcium-related variables in blood and urine.

RESULTS

Dietary calcium, phosphorus and protein intakes were significantly lower in the women from Jakarta than in those from Adelaide (all P < 0.001), probably because of lower milk consumption, but energy intake was similar in the two cities. Indonesian women were shorter and lighter than Australian women (P < 0.001) but had a comparable body mass index (BMI). The Indonesians also had a lower spinal BMD than the Australians but this was accounted for by the differences in height and weight between the two populations. The differences in serum and urinary calcium and phosphate and serum alkaline phosphatase across the menopause were comparable in Indonesian and Australian women but creatinine excretion was 25% lower in Jakarta than in Adelaide (P < 0.001) and this was probably sufficient to account for higher ratios of some urinary solutes to urinary creatinine in the Indonesians. Serum 25-hydroxyvitamin D (25OHD) levels were significantly lower (P < 0.001) and serum PTH levels significantly higher (P = 0.0045) in Jakarta than in Adelaide.

CONCLUSIONS

The differences in bone-related biochemical variables across the menopause were similar in the two populations, but calcium and protein intake and urine creatinine were lower in Indonesian than in Australian women. Serum 25OHD was lower and PTH higher in the Indonesian women, probably because of their darker skin, their practice of avoiding direct sunlight and the heavy atmospheric pollution in Jakarta.

Seasonal change in osteoid thickness and mineralization lag time in ambulant patients

Low vitamin D levels are common. Bone biopsies taken from 121 ambulant patients were therefore reviewed. Seasonal changes in mineralization correlated inversely with serum 25-hydroxyvitamin D but not the more active metabolite, 1,25-dihydroxyvitamin D. This implies that the latter is produced in bone.

INTRODUCTION

It has been 30 yr since a seasonal variation in osteoid surfaces and calcification fronts was noted in bone biopsies from hip fracture patients in Leeds and attributed to vitamin D status. It was suggested at that time that mild vitamin D deficiency might cause osteoporosis from malabsorption of calcium and more severe deficiency osteomalacia, but little has been published on this subject since.

MATERIALS AND METHODS

We examined bone biopsies, calcium absorption data, and serum vitamin D metabolites in 121 patients attending our osteoporosis clinics in Adelaide. Biopsies were collected from the anterior iliac crest with a Jamshidi needle after two stat oral doses of 1 g of tetracycline 10 days apart, processed into plastic without demineralization, and all parameters were measured by point counting using a Weibel II graticule. Calcium absorption was measured after an oral dose of 5 microCi of (45)Ca in 250 ml of water with 20 mg of calcium carrier. Serum 25-hydroxyvitamin D [25(OH)D] was measured by radioimmunoassay and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] by radioimmunoassay after high-performance liquid chromatography (HPLC).

RESULTS

25(OH)D levels were lower from late autumn to early spring (April to September) than from late spring to early autumn (October to March) (51 +/- 23 versus 61 +/- 27 [SD] nM; p=0.040). None of the biopsies yielded a diagnosis of osteomalacia, but osteoid thickness (O.Th.) was greater in the winter than the summer months (8.5 +/- 3.6 versus 7.1 +/- 2.8 microm; p=0.015) as was mineralization lag time (MLT; 11.9 +/- 5.2 versus 9.5 +/- 3.6; p=0.005). O.Th and log MLT were both inversely related to serum 25(OH)D (p=0.014 and 0.036) but not serum 1,25(OH)(2)D. Calcium absorption was related to serum 1,25(OH)(2)D but not serum 25(OH)D.

CONCLUSIONS

We conclude that circulating 25(OH)D affects the mineralization process, whereas circulating 1,25(OH)(2)D affects bone indirectly through its effect on calcium absorption.

Discriminative ability of dual-energy X-ray absorptiometry site selection in identifying patients with osteoporotic fractures

Dual-energy X-ray absorptiometry (DXA) is the gold standard method for measurement of bone mineral density (BMD). The aims of the current study are to compare the ability of BMD measurements to identify subjects with vertebral fractures (VF), when the lumbar spine (LS), hip or both sites are measured. 460 subjects aged 73+/-5.2 years participated in the study. Thoraco-lumbar spine radiographs were obtained and analyzed for the presence of VF using the visual semi-quantitative assessment. BMD of the LS and the left femur were measured by DXA. Eighteen men (12%) and 56 women (20%) had at least one VF. 16% of scans at the LS were unreadable because of the presence of degenerative changes. In both genders, BMD of the hip showed better ability than LS BMD in detecting subjects with osteoporosis. BMD and T-score values at the hip, but not the LS, were lower in subjects with VF than those without (p<0.05). Femoral neck BMD showed the highest OR for each S.D. decrease in BMD for identifying subjects with VF, and the best predictability for prevalent VF using ROC. Fracture risk prediction did not increase by adding the spine to the hip measurement. In conclusion, hip BMD was the only and best skeletal site needed to detect subjects with osteoporosis and showed the strongest relationship with prevalent vertebral fractures in elderly subjects.

Vertebral fracture risk and impact of database selection on identifying elderly Lebanese with osteoporosis

The International Osteoporosis Foundation recommends using a universal database i.e. the NHANES database for the diagnosis of osteoporosis. Population-based databases for T-score calculation are still debated in terms of clinical and public health relevance. The current study aimed at estimating the prevalence of vertebral fractures in the Lebanese elderly, determining BMD-fracture relationship, and assessing the effect of database selection on osteoporosis prevalence and fracture risk assessment. Apparently healthy subjects were randomly selected from the Greater Beirut area - one-third of the Lebanese population at large - using a multilevel cluster technique. Subjects with medical conditions likely to affect bone metabolism i.e. history of major chronic disease, intake of medications that affect bone metabolism were excluded. Presence of vertebral fracture was estimated by a semi-quantitative assessment. Bone density was measured by central DXA. Clinical risk factors included age, gender, height, weight, body mass index, smoking, exercise, falls, previous fragility fracture and family history of fragility fracture. Impact of database selection was assessed by: (1) Comparison of sensitivity and specificity for prevalent vertebral fractures of the T-score <or= - 2.5 threshold using local versus NHANES database. (2) Comparison of estimates for fracture risk (RR/SD decrease in BMD) using local versus NHANES database. Prevalence of vertebral fractures was estimated at 19.9% [15.4-25.0] in women and at 12.0% [7.3-18.3] in men. Prevalence of osteoporosis by DXA using total hip was 33.0% [27.5-38.8] in women and 22.7% [16.2-30.2] in men. The NHANES database provided higher sensitivity for vertebral fracture than our population-specific database. RR of vertebral fracture per SD decrease in BMD remained unchanged across the two databases. In women, RR/SD were 1.61 [1.17-2.23] and 1.49 [1.14-1.95] in the NHANES and the local database, respectively, and in men 1.59 [0.94-2.72] and 1.43 [0.95-2.16]. In conclusion, our findings were in concordance with the IOF recommendations for the use of a universal database and could be used for the implementation of a unified fracture risk assessment paradigm along with the WHO initiative.