Serum vitamin D metabolites and calcium absorption in normal young and elderly free-living women and in women living in nursing homes

Vitamin D, Calcium, Parathyroid Hormone, and Sex Steroids in Bone Health and Effects of Aging

Bone health of the elderly is a major global health concern, since about 1 in 3 women and 1 in 5 men suffer from bone loss and fractures, often called osteoporosis, in old age. Bone health is a complex issue affected by multiple hormones and minerals. Among all the hormones involved in bone health, calcitriol (also vitamin D), parathyroid, and sex hormones (especially estrogen) have been discussed in this review paper. We have discussed the metabolism of these hormones and their effects on bone health. Vitamin D can be obtained from diet or formed from 7-dehydrocholesterol found under the skin in the presence of sunlight. The active form, calcitriol, causes dimerization of vitamin D receptor and acts on the bones, intestine, and kidney to regulate the level of calcium in blood. Similarly, parathyroid hormone is secreted when the serum level of calcium is low. It helps regulate the level of blood calcium through calcitriol. Sex hormones regulate bone modeling at an early age and remodeling later in life. Loss of ovarian function and a decrement in the level of production of estrogen are marked by bone loss in elderly women. In the elderly, various changes in the calcium and vitamin D metabolism, such as decrease in the production of vitamin D, decrease in dietary vitamin D, decreased renal production, increased production of excretory products, decrease in the level of VDR, and decreased calcium absorption by the intestines, can lead to bone loss. When the elderly are diagnosed with osteoporosis, medications that directly target bone such as bisphosphonates, RANK ligand inhibitors, estrogen and estrogen analogues, estrogen receptor modulators, and parathyroid hormone receptor agonists are used. Additionally, calcium and vitamin D supplements are prescribed.

Association Between Vitamin D, Frailty, and Progression of Frailty in Community-Dwelling Older Women

CONTEXT

Vitamin D (25OHD) is involved in many physiological functions that decline with age, contributing to frailty and increased risk for negative health outcomes. Whether 25OHD is a long-term risk marker for frailty over a longer time and whether it is consistent with advancing age is unclear.

OBJECTIVE

To investigate the association between 25OHD and frailty in older women followed for 10 years.

DESIGN AND SETTING

Prospective, population-based, cohort study in Malmö, Sweden.

PARTICIPANTS

Community-dwelling women, age 75 years (N = 1044) with reassessments at ages 80 (n = 715) and 85 (n = 382) years.

METHODS

Frailty was quantified using a 10-variable frailty index. Women were categorized as 25OHD insufficient (<50 nmol/L) or sufficient (≥50 nmol/L).

RESULTS

At ages 75 and 80 years, women with insufficient 25OHD were frailer than women with sufficient 25OHD (0.23 vs 0.18, P < 0.001; and 0.32 vs 0.25, P = 0.001, respectively). At age 80 years, 25OHD insufficiency was associated with subsequent frailty 5 years later (0.41 vs 0.32; P = 0.011). Accelerated progression of frailty was not associated with lower 25OHD levels, and 25OHD level >75 nmol/L was not additionally beneficial with regard to frailty. No association between 25OHD and frailty was observed at age 85 years. Within the frailty index, variables associated with 25OHD were related to muscle strength and function.

CONCLUSION

In this study, 25OHD insufficiency was associated with increased frailty in all but the oldest old. This study supports the value of maintaining sufficient 25OHD levels for healthy aging.

Is there a role for vitamin D in supporting cognitive function as we age?

Globally, an estimated 46 million people are currently living with dementia and this figure is projected to increase 3-fold by 2050, highlighting this major public health concern and its substantial associated healthcare costs. With pharmacological treatment yet to reach fruition, the emphasis on evidence-based preventative lifestyle strategies is becoming increasingly important and several modifiable lifestyle factors have been identified that may preserve cognitive health. These include good cardiovascular health, physical activity, low alcohol intake, smoking and a healthy diet, with growing interest in vitamin D. The aim of the present paper is to review the evidence supporting the potential roles of vitamin D in ageing and cognitive health in community-dwelling older adults. Furthermore, to describe the utility and challenges of cognitive assessments and outcomes when investigating vitamin D in this context. Evidence indicates that serum 25-hydroxyvitamin D (25(OH)D) may impact brain health. There is a biological plausibility from animal models that vitamin D may influence neurodegenerative disorders, through several mechanisms. Epidemiological evidence supports associations between low serum 25(OH)D concentrations and poorer cognitive performance in community-dwelling older populations, although an optimal 25(OH)D level for cognitive health could not be determined. The effect of raising 25(OH)D concentrations on cognitive function remains unclear, as there is a paucity of interventional evidence. At a minimum, it seems prudent to aim to prevent vitamin D deficiency in older adults, with other known common protective lifestyle factors, as a viable component of brain health strategies.

Changes in vitamin D endocrinology during aging in adults

Worldwide, vitamin D deficiency is a common finding. Within individuals 25-hydroxyvitamin D (25OH)D) concentrations remain fairly stable over time although large differences in individual longitudinal changes exist. During aging vitamin D metabolism and activity changes in several different ways. Intestinal resistance to 1,25(OH)2D develops which hampers intestinal calcium uptake. Vitamin D receptor number decreases with aging in several organs involved in calcium metabolism and 1alpha-hydroxylase activity decreases mainly due to a decrease in renal function reducing vitamin D activation. Effects of 1,25(OH)2D on cell proliferation and differentiation may influence potential anti-cancer effects whereas regulation of telomere length may result in longevity. In older individuals, vitamin D supplementation has positive effects on fracture risk, number of falls and physical function. Supplementation in older populations warrants specific attention. Effects on "non-classical" outcomes may be revealed by ongoing large randomized clinical trials with high doses of vitamin D.

Vitamin D and male reproductive system

Vitamin D deficiency is a highly prevalent worldwide condition and affects people of all ages. The most important role of vitamin D is the regulation of intestinal calcium absorption and metabolism of calcium and phosphorus to maintain muscle and bone homeostasis. Furthermore, in recent years it has been discovered that the vitamin D receptor (VDR) is widely distributed in many organs and tissues where vitamin D can perform other actions that include the modulation of the immune response, insulin secretion, anti-proliferative effect on cells of vascular smooth muscle, modulation of the renin-angiotensin-aldosterone system and regulates cell growth in several organs. The VDR is widely distributed in the male reproductive system. Vitamin D induces changes in the spermatozoa's calcium and cholesterol content and in protein phosphorylation to tyrosine/threonine residues. These changes could be involved in sperm capacitation. Vitamin D seems to regulate aromatase expression in different tissues. Studies analyzing seasonal variations of sex steroids in male populations yield conflicting results. This is probably due to the wide heterogeneity of the populations included according to age, systemic diseases and obesity.

Effects of adding chymosin to milk on calcium homeostasis: a randomized, double-blind, cross-over study

Calcium intake and absorption is important for bone health. In a randomized double-blind cross-over trial, we investigated effects of adding chymosin to milk on the intestinal calcium absorption as measured by renal calcium excretion and indices of calcium homeostasis. The primary outcome of the study was 24-h renal calcium excretion that is considered a proxy measure of the amount of calcium absorbed from the intestine. We studied 125 healthy men and women, aged 34 (25-45) years on two separate days. On each day, a light breakfast was served together with 500 ml of semi-skimmed milk to which either chymosin or similar placebo was added. Compared with placebo, chymosin did not affect 24-h urinary calcium, calcium/creatinine ratio, plasma parathyroid hormone, calcitonin or ionized calcium levels. However, during the first 4 h after intake of milk with chymosin, urinary calcium-creatinine ratio was significantly increased (17%) compared with placebo. Stratification by daily calcium intake showed effect of chymosin in participant with a habitual intake above the median (>1,050 mg/day) in whom both urinary calcium and calcium/creatinine ratio were significantly increased compared with placebo. Effects did not depend on plasma 25-hydroxyvitamin D levels. Chymosin added to milk increases renal calcium excretion in the hours following intake without affecting plasma levels of calcium or calciotropic hormones. The effect most likely represents enhanced intestinal calcium absorption shortly after intake. Further studies are warranted on whether intake of milk-added chymosin may cause beneficial effects on bone. www.ClinicalTrials.gov no. NCT01370941.

Vitamin D and aging

Age-related changes affect vitamin D metabolism and increase the requirement for vitamin D in the elderly. Also there is an age related decrease in calcium absorption and a higher calcium intake is needed. Increasing calcium from dietary sources may be better than supplements, and requires increasing the intake of dairy products or other and calcium-fortified foods. Evidence suggests that vitamin D and calcium nutrition can be improved in the elderly by increasing the vitamin D intake to 800 IU daily together with a total calcium intake of 1000 mg daily. This combination is a simple, inexpensive strategy that can reduce fractures in institutionalized individuals by 30%.

Vitamin D supplementation in older adults: searching for specific guidelines in nursing homes

BACKGROUND

The prevalence of vitamin D insufficiency is very high in the nursing home (NH) population. Paradoxically, vitamin D insufficiency is rarely treated despite of strong clinical evidence and recommendations for supplementation. This review aims at reporting the current knowledge of vitamin D supplementation in NH and proposing recommendations adapted to the specificities of this institutional setting.

DESIGN

Current literature on vitamin D supplementation for NH residents was narratively presented and discussed by the French Group of Geriatrics and Nutrition.

RESULT

Vitamin D supplementation is a safe and well-tolerated treatment. Most residents in NH have vitamin D insufficiency, and would benefit from vitamin D supplement. However, only few residents are actually treated. Current specific and personalized protocols for vitamin D supplementation may not be practical for use in NH settings (e.g., assessment of serum vitamin D concentrations before and after supplementation). Therefore, our group proposes a model of intervention based on the systematic supplementation of vitamin D (1,000 IU/day) since the patient's admission to the NH and throughout his/her stay without the need of a preliminary evaluation of the baseline levels. Calcium should be prescribed only in case of poor dietary calcium intake.

CONCLUSION

A population-based rather than individual-based approach may probably improve the management of vitamin D insufficiency in the older population living in NH, without increasing the risks of adverse health problems. The clinical relevance and cost effectiveness of this proposal should be assessed under NH real-world conditions to establish its feasibility.

Low calcidiol levels and risk of progression of aortic calcification

In this observational study, we found a positive relationship between low calcidiol levels and the risk of aortic calcification progression. A 10-ng/mL increase of calcidiol was associated with a decrease in the risk of progression by 44%. This figure was higher than that observed if we increased age by 10 years.

INTRODUCTION

The aim of this study was to investigate the relationship between serum calcidiol levels and the onset and progression of aortic calcifications in a community-based sample of ambulatory subjects.

METHODS

Three hundred two men and women aged 50 and over underwent two lateral X-rays and were followed up for 4 years. Abdominal aortic calcifications were classified as absent, mild-moderate, and severe. The biochemical measurements of serum calcium, phosphorus, parathyroid hormone, total alkaline phosphatase, tartrate-resistant acid phosphatase, creatinine, calcidiol, calcitriol, and osteocalcin were determined. Subjects who had received anti-osteoporotic treatments were excluded from the analysis.

RESULTS

Subjects with progression of aortic calcifications had significantly lower serum calcidiol levels than those without progression. In the multivariate analysis, using the agreed upon serum levels for calcidiol (>30 ng/mL) as the reference, those subjects with calcidiol levels between 10 and 20 ng/mL showed a higher risk of progression of aortic calcification (odds ratio (OR) = 3.95; 95% confidence interval (CI) = 1.16 to 13.40). An even higher OR was observed in subjects with calcidiol values <10 ng/mL (OR = 4.10; 95% CI = 1.12 to 14.99). In addition, an increase by 1 ng/mL in osteocalcin levels was associated with a 17% reduction of the risk of aortic calcification progression.

CONCLUSIONS

An increase by 10 ng/mL of calcidiol was associated with a decrease in the risk of aortic calcifications progression by 44%. This figure was even higher than that observed if we increased age by 10 years. Levels of calcidiol higher than 30 ng/mL seem to be desirable to reduce the progression of aortic calcification and to maintain bone turnover.

Defining vitamin D status by secondary hyperparathyroidism in the U.S. population

BACKGROUND

Vitamin D is associated with a variety of health outcomes, but the exact definition of vitamin D sufficiency remains controversial.

AIM

We sought to define skeletal-related vitamin D sufficiency by estimating maximum PTH suppression in the U.S. population.

METHODS

We performed a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES), 2003-2006. We examined the association between serum 25-hydroxyvitamin D (25OHD) level and serum PTH level in 14,681 participants aged ≥6 yr. We also evaluated the 25OHD-PTH association using 2 thresholds of hyperparathyroidism: PTH≥45 pg/ml and ≥75 pg/ml.

RESULTS

The mean 25OHD level was 24 ng/ml and mean PTH was 42 pg/ml. PTH≥45 pg/ml was present in 35% of the population, while PTH≥75 pg/ml was present in 7%. The prevalence of 25OHD levels <40 ng/ml and <30 ng/ml was 95% and 77%, respectively. In both unadjusted and adjusted models, there was a strong inverse relationship between 25OHD and PTH. Compared to 25OHD≥40 ng/ml, the 25OHD-PTH association was 2.36 [95% confidence interval (CI), 2.08-2.67] times greater for 25OHD<5 ng/ml and 1.12 (95%CI, 1.07-1.17) times greater for 25OHD 30-39.9 ng/ml. Compared to 25OHD≥40 ng/ml, 25OHD levels of 20- 29.9 ng/ml [odds ratio (OR) 2.0 (95%CI, 1.4-2.8)] but not 30- 39.9 ng/ml [OR 1.1 (95%CI, 0.8-1.6)] were independently associated with PTH≥45 pg/ml.

CONCLUSIONS

Optimal vitamin D status, defined by estimated maximum PTH suppression, does not occur until at least 25OHD levels ≥40 ng/ml. Using these thresholds, most of the U.S. population needs more vitamin D. Large, prospective studies are needed to determine optimal vitamin D supplementation.

The 2011 IOM report on vitamin D and calcium requirements for north america: clinical implications for providers treating patients with low bone mineral density

Vitamin D is an essential nutrient for skeletal mineralization and maintenance of bone mass. Most healthy individuals can meet their vitamin D requirements through dietary means, modest supplementation and solar exposure for short periods of time. The serum level of 25OHD that determines adequacy is 20 ng/ml, which corresponds with consumption of 6-800 IU of vitamin D per day, according to the Institute of Medicine review. There is still debate about whether higher doses of vitamin D are required for treating patients with osteoporosis.

Management of osteoporosis in the elderly

BACKGROUND

Osteoporosis is predominantly a condition of the elderly, and the median age for hip fracture in women is approximately 83 years. Osteoporotic fracture risk is multifactorial, and often involves the balance between bone strength and propensity for falling.

OBJECTIVE

To present an overview of the available evidence, located primarily by Medline searches up to April, 2009, for the different management strategies aimed at reducing the risk of falls and osteoporotic fractures in the elderly.

RESULTS

Frailty is an independent predictor of falls, hip fractures, hospitalisation, disability and death in the elderly that is receiving increasing attention. Non-pharmacological strategies to reduce fall risk can prevent osteoporotic fractures. Exercise programmes, especially those involving high doses of exercise and incorporating balance training, have been shown to be effective. Many older people, especially the very elderly and those living in care institutions, have vitamin D inadequacy. In appropriate patients and given in sufficient doses, vitamin D and calcium supplementation is effective in reducing both falls and osteoporotic fractures, including hip fractures. Specific anti-osteoporosis drugs are underused, even in those most at risk of osteoporotic fracture. The evidence base for the efficacy of most such drugs in the elderly is incomplete, particularly with regard to nonvertebral and hip fractures. The evidence base is perhaps most complete for the relatively recently introduced drug, strontium ranelate. Non-adherence to treatment is a substantial problem, and may be exacerbated by the requirements for safe oral administration of bisphosphonates.

CONCLUSION

Evidence-based strategies are available for reducing osteoporotic fracture risk in the elderly, and include exercise training, vitamin D and calcium supplementation, and use of evidence-based anti-osteoporotic drugs. A positive and determined approach to optimising the use of such strategies could reduce the burden of osteoporotic fractures in this high-risk group.

Estimation of the dietary requirement for vitamin D in free-living adults >=64 y of age

BACKGROUND

Older adults may be more prone to developing vitamin D deficiency than younger adults. Dietary requirements for vitamin D in older adults are based on limited evidence.

OBJECTIVE

The objective was to establish the dietary intake of vitamin D required to maintain serum 25-hydroxyvitamin D [25(OH)D] concentrations above various cutoffs between 25 and 80 nmol/L during wintertime, which accounted for the effect of summer sunshine exposure and diet.

DESIGN

A randomized, placebo-controlled, double-blind, 22-wk intervention was conducted in men and women aged >/=64 y (n = 225) at supplemental levels of 0, 5, 10, and 15 microg vitamin D(3)/d from October 2007 to March 2008.

RESULTS

Clear dose-related increments (P < 0.0001) in serum 25(OH)D were observed with increasing supplemental vitamin D(3) intakes. The slope of the relation between total vitamin D intake and serum 25(OH)D was 1.97 nmol . L(-1) . microg intake(-1). The vitamin D intake that maintained serum 25(OH)D concentrations >25 nmol/L in 97.5% of the sample was 8.6 microg/d. Intakes were 7.9 and 11.4 microg/d in those who reported a minimum of 15 min daily summer sunshine exposure or less, respectively. The intakes required to maintain serum 25(OH)D concentrations of >37.5, >50, and >80 nmol/L in 97.5% of the sample were 17.2, 24.7, and 38.7 microg/d, respectively.

CONCLUSION

To ensure that the vitamin D requirement is met by the vast majority (>97.5%) of adults aged >/=64 y during winter, between 7.9 and 42.8 microg vitamin D/d is required, depending on summer sun exposure and the threshold of adequacy of 25(OH)D. This trial was registered at http://www.controlled-trials.com/ISRCTN20236112 as ISRCTN registration no. ISRCTN20236112.

Age, race and season predict vitamin D status in African American and white octogenarians and centenarians

OBJECTIVE

Poor vitamin D status has been associated with osteoporosis, falls, cardiovascular diseases, cancer, autoimmune diseases, pain, nursing home placement, and other age-related conditions, but little is known about the prevalence and predictors of vitamin D status in those aged 80 and older. Thus, this study tested the hypothesis that vitamin D status would be 1) poorer in a population-based multi-ethnic sample of centenarians as compared with octogenarians and 2) predicted by specific dietary, demographic or environmental factors.

DESIGN

Cross-sectional population-based analyses.

SETTING

Northern Georgia in the United States.

PARTICIPANTS

Men and women aged 80 to 89 (octogenarians, n=80) and 98 and older (centenarians, n=237).

MEASUREMENTS

Regression analyses were used to examine the associations of serum 25-hydroxyvitamin D [25(OH)D] with age, gender, race, living arrangements, dairy food intake, supplement intake, and season.

RESULTS

The prevalence of vitamin D insufficiency [25(OH)D<50 nmol/L] was higher in centenarians than in octogenarians (p<0.02). In logistic regression analyses, the risk of being vitamin D insufficient was significantly increased by being a centenarian vs. octogenarian (p<0.005) and by being African American vs. white (p<0.001) and decreased by taking a supplement with vitamin D (p<0.001) or by having vitamin D status measured in the summer or fall (each p<0.05), compared with spring.

CONCLUSIONS

Centenarians and octogenarians are at high risk for vitamin D insufficiency for many of the same reasons identified in younger populations. Given the numerous potential adverse consequences of poor vitamin D status, efforts are needed to ensure vitamin D adequacy in these older adults.

Estimation of the dietary requirement for vitamin D in healthy adults

BACKGROUND

Knowledge gaps have contributed to considerable variation among international dietary recommendations for vitamin D.

OBJECTIVE

We aimed to establish the distribution of dietary vitamin D required to maintain serum 25-hydroxyvitamin D [25(OH)D] concentrations above several proposed cutoffs (ie, 25, 37.5, 50, and 80 nmol/L) during wintertime after adjustment for the effect of summer sunshine exposure and diet.

DESIGN

A randomized, placebo-controlled, double-blind 22-wk intervention study was conducted in men and women aged 20-40 y (n = 238) by using different supplemental doses (0, 5, 10, and 15 microg/d) of vitamin D(3) throughout the winter. Serum 25(OH)D concentrations were measured by using enzyme-linked immunoassay at baseline (October 2006) and endpoint (March 2007).

RESULTS

There were clear dose-related increments (P < 0.0001) in serum 25(OH)D with increasing supplemental vitamin D(3). The slope of the relation between vitamin D intake and serum 25(OH)D was 1.96 nmol x L(-1) x microg(-1) intake. The vitamin D intake that maintained serum 25(OH)D concentrations of >25 nmol/L in 97.5% of the sample was 8.7 microg/d. This intake ranged from 7.2 microg/d in those who enjoyed sunshine exposure, 8.8 microg/d in those who sometimes had sun exposure, and 12.3 microg/d in those who avoided sunshine. Vitamin D intakes required to maintain serum 25(OH)D concentrations of >37.5, >50, and >80 nmol/L in 97.5% of the sample were 19.9, 28.0, and 41.1 microg/d, respectively.

CONCLUSION

The range of vitamin D intakes required to ensure maintenance of wintertime vitamin D status [as defined by incremental cutoffs of serum 25(OH)D] in the vast majority (>97.5%) of 20-40-y-old adults, considering a variety of sun exposure preferences, is between 7.2 and 41.1 microg/d.

Plasma 1,25(OH)2D levels decrease in postmenopausal women with hypovitaminosis D

OBJECTIVE

Although calcitriol (1,25(OH)2D) is considered the biologically active vitamin D metabolite, several studies have shown that calcidiol (25OHD) is the vitamin D metabolite that is most closely linked to parathyroid function and indices of calcium homeostasis. Moreover, low levels of 25OHD have been associated with increased risk of different diseases including cancer, diabetes, and myopathy.

DESIGN

Cross-sectional study.

METHODS

We studied relations between plasma concentrations of 25OHD, 1,25(OH)2D, and parathyroid hormone (PTH) in fasting plasma samples from 315 healthy postmenopausal women randomly selected from the local background population.

RESULTS

P-1,25(OH)2D levels varied in a concentration-dependent manner with P-25OHD levels (P<0.001). Thus, P-1,25(OH)2D levels were the lowest in women with vitamin D insufficiency, i.e., P-1,25(OH)2D levels were reduced by approximately one-third in subjects with P-25OHD levels below 25 nmol/l compared with levels above 80 nmol/l (P<0.01). The association was most pronounced at P-25OHD concentrations below 80 nmol/l, whereas no major increase in P-1,25(OH)2D was observed at P-25OHD concentrations above 80 nmol/l. In multiple regression analysis, PTH was a minor although significant predictor of P-1,25(OH)2D levels.

CONCLUSIONS

In normal postmenopausal women, the conversion of 25OHD to active vitamin D depends on the substrate concentration. Our data support that vitamin D insufficiency should be considered at P-25OHD levels below 80 nmol/l.

The health benefits of calcium citrate malate: a review of the supporting science

There has been considerable investigation into the health benefits of calcium citrate malate (CCM) since it was first patented in the late 1980s. This chapter is a comprehensive summary of the supporting science and available evidence on the bioavailability and health benefits of consuming CCM. It highlights the important roles that CCM can play during various life stages. CCM has been shown to facilitate calcium retention and bone accrual in children and adolescents. In adults, it effectively promotes the consolidation and maintenance of bone mass. In conjunction with vitamin D, CCM also decreases bone fracture risk in the elderly, slows the rate of bone loss in old age, and is of benefit to the health and well-being of postmenopausal women. CCM is exceptional in that it confers many unique benefits that go beyond bone health. Unlike other calcium sources that necessitate supplementation be in conjunction with a meal to ensure an appreciable benefit is derived, CCM can be consumed with or without food and delivers a significant nutritional benefit to individuals of all ages. The chemistry of CCM makes it a particularly beneficial calcium source for individuals with hypochlorydia or achlorydia, which generally includes the elderly and those on medications that decrease gastric acid secretion. CCM is also recognized as a calcium source that does not increase the risk of kidney stones, and in fact it protects against stone-forming potential. The versatile nature of CCM makes it a convenient and practical calcium salt for use in moist foods and beverages. The major factor that may preclude selection of CCM as a preferred calcium source is the higher cost compared to other sources of calcium commonly used for fortification (e.g., calcium carbonate and tricalcium phosphate). However, formation of CCM directly within beverages or other fluid foods and/or preparations, and the addition of a concentrated CCM solution or slurry, are relatively cost-effective methods by which CCM can be incorporated into finished food and beverage products.

Response to teriparatide in patients with baseline 25-hydroxyvitamin D insufficiency or sufficiency

CONTEXT

Serum 25-hydroxyvitamin D (25OHD) concentrations greater than 30 ng/ml have been recommended for lowering fracture risk.

OBJECTIVE

Our objective was to determine whether 25OHD sufficiency is a prerequisite for effective response to teriparatide (TPTD).

DESIGN AND PATIENTS

Data were from 1620 osteoporotic postmenopausal women in the Fracture Prevention Trial. The response to TPTD was assessed in women subgrouped by having 25OHD insufficiency (>10 but <or=30 ng/ml) or 25OHD sufficiency (>30 but <or=183 ng/ml) at the baseline (randomization) visit. An abnormal intact PTH was exclusionary.

INTERVENTIONS

At baseline, after at least 1 month of supplementation with calcium (1000 mg) and vitamin D (400-1200 IU) daily, women were randomized to placebo or 20 or 40 microg TPTD by daily sc injection for a median of 19 months. Observation was for a median of 21 months.

MAIN OUTCOME MEASURES

Main outcome measures included vertebral and nonvertebral fractures, change in bone mineral density at the lumbar spine and femoral neck, change in bone formation marker amino-terminal extension peptide of procollagen type 1, and the proportion of women with serum calcium at least 2.76 mmol/liter 4-6 h after dosing.

RESULTS

TPTD reduced vertebral and nonvertebral fracture risk, increased lumbar spine and femoral neck bone mineral density, and increased amino-terminal extension peptide of procollagen type 1 relative to placebo in the two 25OHD subgroups. There were no significant differences in these endpoints between the subgroups (each treatment by subgroup interaction, P > 0.10). However, it should be noted that because of the limited number of fractures, this study does not exclude the possibility of differences in fracture outcome between the subgroups.

CONCLUSIONS

In postmenopausal women with osteoporosis and normal intact PTH, the responses to TPTD did not differ significantly in women with baseline 25OHD insufficiency or sufficiency.

Prevalence of vitamin D insufficiency in obese children and adolescents

OBJECTIVE

Recent studies have shown a broad prevalence of vitamin D deficiency in adults. Serum 25-hydroxyvitamin D (25-OHD) levels were reported to be inversely related to body mass index (BMI) and body fat content and correlated directly with hypertension, degree of insulin resistance and progression to diabetes mellitus. We sought to determine the prevalence of vitamin D insufficiency and markers of metabolic syndrome in an obese pediatric population.

METHODS

Charts of 217 obese (weight >95th percentile for age and sex) children (118 females, 99 males; mean BMI 32.2 +/- 6.4 kg/m2; mean age 12.9 2 5.5; age range 7-18 years) who had received a standard physical examination at the pediatric endocrine clinic of the Infants and Children's Hospital of Brooklyn at Maimonides, Brooklyn, NY, were retrospectively analyzed. Data obtained included age, sex, weight, BMI, height and systolic and diastolic blood pressure. The routine bloodwork panel for obesity at our pediatric endocrine facility includes fasting 25-OHD, total cholesterol, high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), triglycerides, ALT, AST, thyroid stimulating hormone (TSH), total T4, and insulin and glucose. Insulin sensitivity as calculated by quantitative insulin-sensitivity check index (QUICKI = 1/[log(I0) + log(G0)], where I0 is fasting insulin and G0 is fasting glucose) was computed following the visit.

RESULTS

Overall, 55.2% of patients were vitamin D insufficient (25-OHD <20 ng/ml). Severely low vitamin D levels (25-OHD < or =10 ng/ml) were seen in 21.6% of 217 patients, which represents almost half of the insufficient group. In the 25-OHD <20 ng/ml group age, BMI, and SBP were significantly higher than in the 25-OHD 220 ng/ml group, while QUICKI (<0.35 is consistent with insulin resistance) was borderline low in the <20 ng/ml group. HDL-C was significantly lower in the 25-OHD < or =10 ng/ml group. The 25-OHD levels correlated negatively with BMI and positively with HDL-C. No other findings were significant.

CONCLUSION

More than half of the obese children had vitamin D levels <20 ng/ml with equal gender distribution. Vitamin D insufficiency was associated with increased age, BMI, and SBP, and decreased HDL-C.

Hypovitaminosis D in female patients with chronic low back pain

Chronic low back pain (LBP) is an extremely common problem in practice, where it is often labeled idiopathic. No sufficient studies have been conducted to analyze the contribution of hypovitaminosis D to the etiology of chronic LBP in populations wherein vitamin D deficiency is endemic. The present study was, therefore, carried out to examine hypovitaminosis D and its determinants in female patients with chronic LBP during the childbearing period. Sixty female patients complaining of LBP lasting more than 3 months were clinically studied rheumatologically and neurologically. Questionnaires and indices quantifying risk factors associated with vitamin D deficiency were utilized. Biochemical assays of serum calcium, phosphorus, alkaline phosphatase (ALP), parathormone (PTH), and 25-hydroxyvitamin D (25 OHD) were performed and compared to those of 20 matched healthy controls. The determinants of vitamin D levels in patients were examined by stepwise regression. Patients with LBP had significantly lower 25 OHD levels (p < 0.05) and significantly higher PTH (p < 0.05) and ALP (p < 0.001) than controls, although there were no significant group differences in calcium and phosphorus. Hypovitaminosis D (25 OHD < 40 ng/ml) was found in 49/60 patients (81%) and 12/20 (60%) of controls, with an odds ratio of 2.97. Although many risk factors related to sun exposure, clothing, diet, and pregnancy were significantly correlated with vitamin D levels in patients, only limited duration of sun exposure, contributing 55% to the variance of 25 OHD, limited areas of skin exposed (13%), and increased number of pregnancies (2%), were significant determinants of vitamin D levels in patients. Despite the sunny climate, hypovitaminosis D is prevalent among Egyptian women in the childbearing period, especially those presenting with chronic LBP, where it is associated with hyperphosphatasia and hyperparathyroidism, without alterations in serum calcium. The major determinant of hypovitaminosis D in our patients is limited sun exposure.

The 25-hydroxyvitamin D threshold for better health

Available data supporting a target serum level of at least 75 nmol/l 25-hydroxyvitamin D (25-OHD) include studies on bone mineral density (bmd), fracture prevention, lower extremity function, and cancer prevention. Given the high cost and disability from falls, fractures, and cancer treatment a shared threshold for 25-OHD has significant public health implications, especially so, if a large part of the population is below this threshold. This article summarizes available evidence supporting the 75 nmol/l threshold, reviews adherence to Vitamin D treatment in fracture trials in regard to achieved anti-fracture efficacy, and finally discusses current recommendations for Vitamin D intake.

Alendronate with and without cholecalciferol for osteoporosis: results of a 15-week randomized controlled trial

OBJECTIVE

Many osteoporosis patients have low 25-hydroxyvitamin D (25OHD) and do not take recommended vitamin D amounts. A single tablet containing both cholecalciferol (vitamin D3) and alendronate would improve vitamin D status concurrently, with a drug shown to reduce fracture risk. This study assessed the efficacy, safety, and tolerability of a once-weekly tablet containing alendronate 70 mg and cholecalciferol 70 microg (2800 IU) (ALN + D) versus alendronate 70 mg alone (ALN).

METHODS

This 15-week, randomized, double-blind, multi-center, active-controlled study was conducted during a season when 25OHD levels are declining, and patients were required to avoid sunlight and vitamin D supplements for the duration of the study. Men (n = 35) and postmenopausal women (n = 682) with osteoporosis and 25OHD >or= 9 ng/mL were randomized to ALN + D (n = 360) or ALN (n = 357).

MAIN OUTCOME MEASURES

Serum 25OHD, parathyroid hormone, bone-specific alkaline phosphatase (BSAP), and urinary N-telopeptide collagen cross-links (NTX).

RESULTS

Serum 25OHD declined from 22.2 to 18.6 ng/mL with ALN (adjusted mean change = -3.4; 95% confidence interval [CI]: -4.0 to -2.8), and increased from 22.1 to 23.1 ng/mL with ALN + D (adjusted mean change = 1.2; 95% CI: 0.6 to 1.8). At 15 weeks, adjusted mean 25OHD was 26% higher (p < 0.001, ALN + D versus ALN), the adjusted relative risk (RR) of 25OHD < 15 ng/mL (primary endpoint) was reduced by 64% (incidence 11% vs. 32%; RR = 0.36; 95% CI: 0.27 to 0.48 [p < 0.001]), and the RR of 25OHD < 9 ng/mL (a secondary endpoint) was reduced by 91% (1% vs. 13%; RR = 0.09; 95% CI: 0.03 to 0.23 [p < 0.001]). Antiresorptive efficacy was unaltered, as measured by reduction in bone turnover (BSAP and NTX).

CONCLUSION

In osteoporosis patients who avoided sunlight and vitamin D supplements, this once-weekly tablet containing alendronate and cholecalciferol provided equivalent antiresorptive efficacy, reduced the risk of low serum 25OHD, improved vitamin D status over 15 weeks, and was not associated with hypercalcemia, hypercalciuria or other adverse findings, versus alendronate alone.

Optimal vitamin D status and serum parathyroid hormone concentrations in African American women

BACKGROUND

Optimal vitamin D status for the prevention of osteoporosis has been inferred from examinations of the serum 25-hydroxyvitamin D [25(OH)D] concentration below which there is an increase in serum parathyroid hormone (PTH).

OBJECTIVE

The objectives of the study were to ascertain whether a threshold for serum 25(OH)D exists below which serum PTH increases and whether persons with 25(OH)D above this threshold have lower rates of bone loss than do persons with 25(OH)D below the threshold.

DESIGN

The relation of serum 25(OH)D to serum PTH was analyzed in 208 African American women studied longitudinally for 3 y. These healthy women in midlife were randomly assigned to receive placebo or 800 IU vitamin D3/d; after 2 y, the vitamin D3 supplementation was increased to 2000 IU/d. Both groups received calcium supplements to ensure an adequate calcium intake. A systematic literature review found a wide range of threshold values in part due to varied calcium intake.

RESULTS

A Loess plot suggested a breakpoint between 40 and 50 nmol/L for serum 25(OH)D. A line-line model was fitted to the data, and it showed a spline knot at 44 nmol/L. A heuristic approach verified that PTH does not decline as rapidly when the serum concentration of 25(OH)D is >40 nmol/L as when it is <40 nmol/L. We found no significant difference in rates of bone loss between persons with 25(OH)D concentrations above and below 40 nmol/L.

CONCLUSION

Although a threshold for 25(OH)D can be identified, we suggest that it should not be used to recommend optimal vitamin D status.

Estimation of optimal serum concentrations of 25-hydroxyvitamin D for multiple health outcomes

Recent evidence suggests that vitamin D intakes above current recommendations may be associated with better health outcomes. However, optimal serum concentrations of 25-hydroxyvitamin D [25(OH)D] have not been defined. This review summarizes evidence from studies that evaluated thresholds for serum 25(OH)D concentrations in relation to bone mineral density (BMD), lower-extremity function, dental health, and risk of falls, fractures, and colorectal cancer. For all endpoints, the most advantageous serum concentrations of 25(OH)D begin at 75 nmol/L (30 ng/mL), and the best are between 90 and 100 nmol/L (36-40 ng/mL). In most persons, these concentrations could not be reached with the currently recommended intakes of 200 and 600 IU vitamin D/d for younger and older adults, respectively. A comparison of vitamin D intakes with achieved serum concentrations of 25(OH)D for the purpose of estimating optimal intakes led us to suggest that, for bone health in younger adults and all studied outcomes in older adults, an increase in the currently recommended intake of vitamin D is warranted. An intake for all adults of > or =1000 IU (25 microg) [DOSAGE ERROR CORRECTED] vitamin D (cholecalciferol)/d is needed to bring vitamin D concentrations in no less than 50% of the population up to 75 nmol/L. The implications of higher doses for the entire adult population should be addressed in future studies.

Vitamin D Deficiency and Osteoporosis in Rehabilitation Inpatients

OBJECTIVE

To determine vitamin D status and bone mineral density (BMD) in patients admitted to a subacute rehabilitation facility.

DESIGN

Cross-sectional cohort study.

SETTING

Subacute rehabilitation facility.

PARTICIPANTS

Fifty-three community-dwelling patients admitted from June through February 2005.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

BMD, 25-hydroxyvitamin D (25[OH]D), C-telopeptide (CTX), osteocalcin, and dietary milk intake.

RESULTS

Prevalence of vitamin D deficiency (25[OH]D <20 ng/mL) was 49.1%, while a total of 83% of patients were either vitamin D deficient or insufficient (25[OH]D <30 ng/mL). The prevalence of osteopenia (T score, <-1) was 52.8%; osteoporosis (T score, <-2.5) was 17.0%. CTX (bone resorption marker) was elevated in 60.4% of patients. Osteocalcin (bone formation marker) was elevated in 13.2% of patients. Measurements of bone resorption and formation positively correlated (R2 = .22) indicating increased bone remodeling.

CONCLUSIONS

Vitamin D deficiency and osteopenia and osteoporosis were highly prevalent in patients admitted for rehabilitation. Elevated bone resorption and remodeling were evident. This could be due to vitamin D deficiency that should be corrected before antiresorptive therapy is considered. The study emphasizes the need for vigilance for vitamin D status and BMD testing in patients admitted to rehabilitation facilities.

Between-meal risedronate does not alter bone turnover in nursing home residents

OBJECTIVES

To assess the effect of between-meal weekly risedronate and daily calcium 630 mg and vitamin D 400 IU on bone turnover markers.

DESIGN

Randomized,double-blind,placebo-controlled trial.

SETTING

Skilled nursing home (NH).

PARTICIPANTS

Sixty skilled-NH residents (46 men, 14 women), mean age+/-standard deviation of 76+/-6, were randomized to receive risedronate 30 mg (n=31) or matching placebo (n=29) once weekly for 12 weeks. All received 315 mg calcium with 200 IU vitamin D twice daily.

MEASUREMENTS

Bone-specific alkaline phosphatase (BSAP), N-telopeptide of type 1 collagen (NTx), 25-hydroxyvitamin D (25OHD), and parathyroid hormone were measured at baseline and 6 and 12 weeks.

RESULTS

Risedronate reduced BSAP significantly more than placebo (P<.05) at 6 weeks but not at 12 weeks; no treatment effect on serum NTx was observed. Defining hypovitaminosis D as a serum 25OHD concentration below 32 ng/mL, 50 of 53 (94%) study participants were low at baseline (mean 25OHD 19 ng/mL). Vitamin D levels remained insufficient in 74% of participants after 12 weeks.

CONCLUSION

In this NH population, weekly risedronate administered using a between-meal dosing schedule reduced serum BSAP at 6 weeks of treatment; this effect was not observed at 12 weeks. The overall lack of change in bone turnover markers suggests that this risedronate dose and schedule would not be expected to increase bone density or reduce fracture risk in this population. Hypovitaminosis D was common and not reliably corrected by 400 IU of vitamin D daily. Despite an extremely high osteoporotic fracture risk in NH residents, additional study is required to determine under which conditions pharmacological treatment is efficacious in this population and define approaches that assure vitamin D repletion.

[Vitamin D deficiency in adults: to better understand a new presentation of an old disease]

Vitamin D is synthesized in skin through a reaction mediated by sunlight, and it is metabolized to 25-hydroxyvitamin D, in liver, and in 1,25-dihydroxyvitamin D, in kidney. This last reaction has a tight feedback mechanism. 1,25-dihydroxyvitamin D is the active hormone, and its actions are mediated mainly by nuclear receptors. Its major functions are in calcium metabolism and bone mass maintenance. Hypovitaminosis D, as a disease in adult people, manifests itself with hypocalcemia and secondary hyperparathyroidism with subsequent loss of trabecular bone, thinning of cortical bone, and, eventually, a higher risk of fractures. Hypovitaminosis D is a very common condition in Europe, Africa, North America and some South American countries, such as Chile and Argentina. Measurement of serum total 25-hydroxyvitamin D concentration is the gold standard to diagnose vitamin D deficiency. Serum concentrations below 50 nmol/L are associated with an increase in parathyroid hormone concentration, and bone loss. Risk factors for vitamin D deficiency, like poor sunlight exposition, aging skin and factors that interfere with normal vitamin D metabolism, are well established. Oral vitamin D supplementation, an easy and inexpensive treatment, is needed to treat this illness.

The Importance of Parathyroid Hormone and Vitamin D Status in the Treatment of Osteoporosis and Renal Insufficiency

Suboptimal vitamin D status is common in sick, elderly patients and is associated with secondary hyperparathyroidism, increased bone turnover, and accelerated bone loss. Nutritional supplementation of elderly patients with vitamin D and calcium has been associated with a reduction in fractures and falls. Recently, the National Kidney Foundation (NKF) recommended screening parathyroid hormone (PTH) levels in those with glomerular filtration rates (GFR) less than 60 mL/min. The PTH target range increases as renal failure progresses because of skeletal resistance. When PTH levels are above the target range, measurement of serum 25-hydroxyvitamin D (25-OH-D) is recommended. If the 25-OH-D level is less than 30 ng/mL, supplementation with vitamin D is recommended. Practitioners should consider supplementing most residents with vitamin D and calcium or follow NKF guidelines.

High prevalence of vitamin D inadequacy and implications for health

During the past decade, major advances have been made in vitamin D research that transcend the simple concept that vitamin D is Important for the prevention of rickets in children and has little physiologic relevance for adults. Inadequate vitamin D, in addition to causing rickets, prevents children from attaining their genetically programmed peak bone mass, contributes to and exacerbates osteoporosis in adults, and causes the often painful bone disease osteomalacia. Adequate vitamin D is also important for proper muscle functioning, and controversial evidence suggests it may help prevent type 1 diabetes mellitus, hypertension, and many common cancers. Vitamin D inadequacy has been reported in approximately 36% of otherwise healthy young adults and up to 57% of general medicine inpatients in the United States and in even higher percentages in Europe. Recent epidemiological data document the high prevalence of vitamin D inadequacy among elderly patients and especially among patients with osteoporosis. Factors such as low sunlight exposure, age-related decreases in cutaneous synthesis, and diets low in vitamin D contribute to the high prevalence of vitamin D inadequacy. Vitamin D production from cutaneous synthesis or intake from the few vitamin D-rich or enriched foods typically occurs only intermittently. Supplemental doses of vitamin D and sensible sun exposure could prevent deficiency in most of the general population. The purposes of this article are to examine the prevalence of vitamin D inadequacy and to review the potential implications for skeletal and extraskeletal health.

The effect of aging on intestinal absorption and status of calcium, magnesium, zinc, and copper in rats: a stable isotope study

Many investigators have reported changes in mineral status with age but conflicting observations were done concerning mineral absorption. This study was conducted to clarify the effect of aging on intestinal absorption and status of minerals, using a stable isotope approach. To do so, 40 rats of different ages: 9, 22, 44, and 88 weeks were fed with a semi-purified diet for a total of 30 days. At the beginning of the 4th week, the rats received a stable isotope solution containing (44)Ca, (25)Mg, (67)Zn, and (65)Cu. Individual feces and urine were then collected during 4 consecutive days in order to measure stable isotopes by inductively coupled plasma/mass spectrometry (ICP/MS) and blood and tissues were sampled for mineral status determination. Intestinal absorption of (44)Ca and (67)Zn considerably decreased with age, whereas intestinal (25)Mg absorption decreased only moderately and intestinal (65)Cu absorption was unaffected. Plasma and bone calcium (Ca) were not modified with age whereas urinary Ca excretion considerably increased. Plasma and erythrocyte magnesium (Mg) levels were unaffected with age whereas urinary Mg excretion and Mg bone level decreased. Plasma zinc (Zn) level decreased and bone Zn level increased with age whereas red blood cell and liver Zn level and urinary Zn excretion remained unchanged. Plasma Cu level increased with age whereas liver and bone Cu levels and urinary Cu excretion remained unchanged. These results show that the effect of aging on the intestinal mineral absorption and status differ largely according to the mineral considered. Further studies are required under different nutritional conditions to explore the underlying mechanisms during aging and to adjust a better nutrition of the elderly.

Influence of ultraviolet radiation on the production of 25 hydroxyvitamin D in the elderly population in the city of São Paulo (23 degrees 34'S), Brazil

The lack of vitamin D is a major changeable factor involved in the pathophysiology of osteoporosis. Since the major source for this hormone is its cutaneous synthesis via ultraviolet radiation (UVR), we studied the serum level of 25-hydroxyvitamin D (25OHD) in 250 free-living elderly people (79.1 years old) from a subtropical region according to the UVR incidence and its correlations with parathormone (PTH) and ionized calcium. UVR and 25OHD differed according to the season of the year (P<0.001), with greater radiation in the summer and less in the winter, whereas the 25OHD peak and nadir occurred in autumn and spring, respectively. The highest 25OHD mean was 67.2 nmol/l, and the lowest was 29.1 nmol/l corresponding, respectively, to the measure of the month subsequent to the one of most and least sunlight incidence. Clustered by season, the correlation between UVR and 25OHD for the following seasons was r=0.98 and between the PTH and 25OHD of corresponding seasons, r=-0.95. Vitamin D deficiency occurred in 15.4% of patients, insufficiency in 41.9% and secondary hyperparathyroidism in 55%. In conclusion, we found a seasonal variation in 25OHD levels that strongly correlated with the PTH levels when separated by the seasons of the year. The 25OHD levels correlated with the UVR of the previous quarter, requiring no less than 30 days for serum changes arising from exposure to or deprivation of UVR to be observed. The prevalence of vitamin D deficiency/insufficiency found was greater than expected, even when compared to countries exposed to less solar irradiation. Thus, measures to encourage greater sun exposure and food enrichment policies should also be considered.

Dietary recommendations to meet both endocrine and autocrine needs of Vitamin D

In the most recent revision of the dietary recommendations for Americans and Canadians in 1997, a recommended intake for Vitamin D was set in the absence of an estimation of mean requirements. There are now new data to estimate average requirements; however, there must be consideration of factors affecting need in populations and of total body tissue needs including the prevention and treatment of cancer. A recent study provides dietary dose-response data in the absence of sun exposure, and a mean requirement of 12.5microg (500IU) was found for Caucasian men. A seasonal build up (summer) and waning (winter) of Vitamin D stores implies that the requirement of Vitamin D in complete absence of yearly summertime sun exposure would approach levels of intake that mimic Vitamin D gained from sun exposure. High prevalence of Vitamin D insufficiency and the re-emergence of rickets have been observed worldwide. For many countries without mandatory staple food fortification, Vitamin D intake is often too low to sustain healthy circulating levels of 25 hydroxyvitamin D. Even in some countries that require (mandatory) or allow fortification (optional), Vitamin D intakes are low in some groups due to their unique dietary patterns, such as low milk consumption, vegetarian diet, limited or no use of dietary supplements, or changes away from traditional food consumption. Supplement use can significantly increase Vitamin D intakes across all age and gender groups but the benefit is primarily gained in persons whose intakes are close to adequate. African American men and women have greater prevalence of Vitamin D insufficiency, which may be a factor in their susceptibility to certain cancers. New recommendations for Vitamin D should be made for the otherwise healthy populations in greatest need of dietary Vitamin D due to lack of adequate sun exposure.

Vitamin D inadequacy among post-menopausal women: a systematic review

BACKGROUND

Vitamin D inadequacy has been studied extensively, due to concerns about ageing populations, associations with osteoporosis and other disorders (including non-musculoskeletal), and high prevalence.

AIM

To review recent reports on the prevalence of vitamin D inadequacy among post-menopausal women with and without osteoporosis and/or other musculoskeletal diseases.

DESIGN

Systematic review.

METHODS

We reviewed publications in the past 10 years reporting prevalence estimates for vitamin D inadequacy, reported as serum 25(OH)D values below various levels. Thirty published studies in the English language were identified, from January 1994 through April 2004.

RESULTS

In osteoporotic populations, the prevalence of 25(OH) vitamin D concentration <12 ng/ml ranged from 12.5% to 76%, while prevalence rates reached 50% to 70% of patients with a history of fracture(s) using a cut-off of 15 ng/ml. In post-menopausal women, the prevalence of 25(OH) vitamin D concentrations <or=20 ng/ml ranged from 1.6% to 86% for community-living and institutionalized women, respectively. The most common factors associated with inadequate vitamin D levels included limited sun exposure, lack of dietary vitamin D intake, nursing home environment, wintertime, and increasing age (over 70 years).

DISCUSSION

The prevalence of inadequate vitamin D levels appears to be high in post-menopausal women, especially in those with osteoporosis and history of fracture. Vitamin D supplementation in this group might offer scope for prevention of falls and fracture, especially in elderly and osteoporotic populations.

Prevalence of Vitamin D inadequacy among postmenopausal North American women receiving osteoporosis therapy

PURPOSE

To evaluate serum 25-hydroxyvitamin D [25(OH)D] concentrations and factors related to vitamin D inadequacy in postmenopausal North American women receiving therapy to treat or prevent osteoporosis.

METHODS

Serum 25(OH)D and PTH were obtained in 1536 community-dwelling women between November 2003 and March 2004. Multivariate logistic regression was used to assess risk factors for suboptimal (<30 ng/ml) 25(OH)D.

RESULTS

Ninety-two percent of study subjects were Caucasian, with a mean age of 71 yr. Thirty-five percent resided at or above latitude 42 degrees north, and 24% resided less than 35 degrees north. Mean (sd) serum 25(OH)D was 30.4 (13.2) ng/ml: serum 25(OH)D was less than 20 ng/ml in 18%; less than 25 ng/ml in 36%; and less than 30 ng/ml in 52%. Prevalence of suboptimal 25(OH)D was significantly higher in subjects who took less than 400 vs. 400 IU/d or more vitamin D. There was a significant negative correlation between serum PTH concentrations and 25(OH)D. Risk factors related to vitamin D inadequacy included age, race, body mass index, medications known to affect vitamin D metabolism, vitamin D supplementation, exercise, education, and physician counseling regarding vitamin D.

CONCLUSIONS

More than half of North American women receiving therapy to treat or prevent osteoporosis have vitamin D inadequacy, underscoring the need for improved physician and public education regarding optimization of vitamin D status in this population.

Vitamin D deficiency and causative factors in the population of Tehran

BACKGROUND

There are multiple studies in different countries regarding the prevalence of vitamin D deficiency. These studies showed high prevalence of vitamin D deficiency in Asian countries. This study tries to elucidate the prevalence of vitamin D deficiency and its influencing factors in population of Tehran.

METHODS

1210 subjects 20-64 years old were randomly selected. 25 (OH) D serum levels were measured. Duration of exposure to sunlight, the type of clothing and level of calcium intake and BMI were quantified based on a questionnaire.

RESULTS

A high percentage of vitamin D deficiency was defined in the study population. Prevalence of severe, moderate and mild Vitamin D deficiency was 9.5%, 57.6% and 14.2% respectively. Vitamin D serum levels had no significant statistical relation with the duration of exposure to sunlight, kind of clothing and BMI. Calcium intake in the normal vitamin D group was significantly higher than the other groups (714.67 +/- 330.8 mg/day vs 503.39 +/- 303.1, 577.93 +/- 304.9,595.84 +/- 313.6). Vitamin D serum levels in young and middle aged females were significantly lower than the older group.

CONCLUSIONS

Vitamin D deficiency has a high prevalence in Tehran. In order to avoid complications of vitamin D deficiency, supplemental dietary intake seems essential.

Vitamin D status and bone turnover in women with acute hip fracture

Hypovitaminosis D is common in elderly women. Few data are available on vitamin D status and bone turnover in women with acute hip fracture. The aims of this study were to determine whether elderly Italian women with an acute hip fracture also had low vitamin D levels and an increase of bone turnover compared with elderly women with osteoporosis but without fractures. Seventy-four women with acute osteoporotic hip fracture and 73 women with postmenopausal osteoporosis were studied. All women were self-sufficient and had adequate sunlight exposure. To exclude the effect of trauma on serum 25-hydroxycolecalciferol levels and bone markers (bone alkaline phosphatase and C-terminal telopeptides of Type I collagen as indices of bone formation and bone resorption), blood samples were drawn within 24 hours of the fracture. Current data indicated that in our patients the prevalence of hypovitaminosis D is common although to a lesser extent than in women who are housebound. Women with acute hip fractures had a higher prevalence of vitamin deficiency defined as serum 25-hydroxycolecalciferol lower than 12 ng/mL, compared with women with osteoporosis. Moreover, the presence of fracture did not influence the rate of bone formation, whereas the increase in bone resorption could be attributed to an older age of women with acute hip fracture because of similar values of parathyroid hormone levels in the two groups.