Seasonal Variation in 25-Hydroxyvitamin D Concentrations in the Cardiovascular Health Study

Shoben, Abigail B.; Kestenbaum, Bryan; Levin, Gregory P.; Hoofnagle, Andrew N.; Psaty, Bruce M.; Siscovick, David S.; Boer, Ian H. de

doi:10.1093/aje/kwr258

Cited by 94 publications

(93 citation statements)

References 23 publications

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“…In addition, we also showed the extent of seasonal variation in 25-OH-D levels [38]. To our knowledge, no studies to date have described the association between mean sunshine hours and mean 25-OH-D serum levels in central Europe or comparable latitudes (eg, Vancouver, 49°, 17' N).…”

Section: Discussionsupporting

confidence: 52%

Is There an Epidemic Vitamin D Deficiency in German Orthopaedic Patients?

Maier

Jakobs

Roth

et al. 2013

Clinical Orthopaedics &Amp; Related Research

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Background Vitamin D plays an essential role in bone health and muscle function. Some studies have shown a widespread rate of vitamin D deficiency in the general population, but few have reported on the vitamin D status of orthopaedic patients.Questions/purposes We investigated (1) the extent of hypovitaminosis D in orthopaedic patients, (2) seasonal variations in vitamin D levels, and (3) possible risk factors for insufficient vitamin D levels. Methods Vitamin D levels in 1119 patients consecutively admitted to an orthopaedic surgery department in 2011 were measured. To investigate the correlation between climate factors and vitamin D levels, the sunshine hours for each month in 2011 were collected by Deutscher Wetterdienst (the German weather service) in the region where most tested patients lived. The prevalence of normal ([ 30 ng/mL), insufficient (20-30 ng/mL), and deficient (\20 ng/mL) 25-hydroxyvitamin D levels was determined. Univariate and multivariate analyses were used to assess risk factors for insufficient vitamin D levels. Results Overall, 84% of patients had insufficient levels of vitamin D and 60% were vitamin D deficient. Only 15% were in the target range of 30 to 60 ng/mL. The prevalence of low vitamin D levels was greater during winter and months with fewer sunshine hours. Vitamin D levels did not vary according to age, sex, and disease. Individuals with obesity, hypertension, and osteoporosis were more likely to have low vitamin D levels compared with their healthy counterparts. Conclusions There is an alarmingly high rate of hypovitaminosis D and vitamin D deficiency among orthopaedic patients in this region of Germany, whose latitude (

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Section: Discussionsupporting

confidence: 52%

Is There an Epidemic Vitamin D Deficiency in German Orthopaedic Patients?

Maier

Jakobs

Roth

et al. 2013

Clinical Orthopaedics &Amp; Related Research

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“…The degree of seasonal variation was inversely associated with age; this observation is in line with a previous study, 8 and may be explained by decreased outdoor activity with increasing age. Compared with Arabs, Jews have greater increase in serum 25(OH)D in summer-autumn.…”

Section: Discussionsupporting

confidence: 92%

Single measurement of serum 25(OH)D: is classification into month-specific cutpoints useful in accounting for seasonal variation?

2012

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Classification into month-specific cutpoints is used to minimize misclassification associated with single measurement of serum 25(OH)D. This study aims to evaluate this strategy, and to compare it with the widely used classification into overall cutpoints. For this purpose, we studied 69 553 subjects in whom serum 25(OH)D was tested on two different occasions. The level of agreement between the quartiles of the first and second tests was 43.8% between the month-specific quartiles and 43.1% between the overall quartiles. The level of agreement between the quartiles of the two approaches was 80.0% and 94.3% in the first and second test, respectively. The extent of seasonal variation (summer-autumn as compared with winter-spring) of serum 25(OH)D was higher in males and in Jews, inversely associated with baseline levels, body mass index and age, and directly associated with socioeconomic class. The month-specific cutpoint strategy does not seem to offer advantage over the overall cutpoints strategy. Hence, determining the long-term average levels is considered to be the optimal measure of exposure. 3 Most of the association studies between vitamin D and dichotomous outcomes usually rely on a single measurement of serum 25(OH)D level, 4,5 leading to non-differential misclassification of the long-term exposure. Several approaches have been used to minimize exposure biases when creating 25(OH)D exposure categories; classification into month-or season-specific quartiles within each month or season of blood sampling is used by some studies in order to reduce the misclassification. 4,6,7 This approach assumes that subjects remain in their season or month-specific quartiles, 6 which may be representative of the long-term average levels. This study aims to evaluate this strategy, and to compare it with the widely used classification into overall cutpoints not accounting for the time of sampling collection.

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“…Observed to play a role in major organs such as the brain and heart, it aids in prostate, colon and immune cell regulation [1][2][3][4], with deficiency being associated with various skeletal and non-skeletal diseases such as rickets [5], diabetes, hypertension [2,3], cancer, cardiovascular and autoimmune diseases [6][7][8] and chronic illnesses. Vitamin D is also related to glycated hemoglobin (HbA 1c ) levels [2] and postural sway [9].…”

Section: Introductionmentioning

confidence: 99%

Do sufficient vitamin D levels at the end of summer in children and adolescents provide an assurance of vitamin D sufficiency at the end of winter? A cohort study

Shakeri

Pournaghi

Hashemi

et al. 2017

Journal of Pediatric Endocrinology and Metabolism

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Background: The changes in serum 25-hydroxyvitamin D (25(OH)D) in adolescents from summer to winter and optimal serum vitamin D levels in the summer to ensure adequate vitamin D levels at the end of winter are currently unknown. This study was conducted to address this knowledge gap. Methods: The study was conducted as a cohort study. Sixty-eight participants aged 7-18 years and who had sufficient vitamin D levels at the end of the summer in 2011 were selected using stratified random sampling. Subsequently, the participants' vitamin D levels were measured at the end of the winter in 2012. A receiver operating characteristic (ROC) curve was used to determine optimal cutoff points for vitamin D at the end of the summer to predict sufficient vitamin D levels at the end of the winter. Results:The results indicated that 89.7% of all the participants had a decrease in vitamin D levels from summer to winter: 14.7% of them were vitamin D-deficient, 36.8% had insufficient vitamin D concentrations and only 48.5% where able to maintain sufficient vitamin D. The optimal cutoff point to provide assurance of sufficient serum vitamin D at the end of the winter was 40 ng/mL at the end of the summer. Sex, age and vitamin D levels at the end of the summer were significant predictors of non-sufficient vitamin D at the end of the winter.

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Seasonal Variation in 25-Hydroxyvitamin D Concentrations in the Cardiovascular Health Study

Cited by 94 publications

References 23 publications

Is There an Epidemic Vitamin D Deficiency in German Orthopaedic Patients?

Is There an Epidemic Vitamin D Deficiency in German Orthopaedic Patients?

Single measurement of serum 25(OH)D: is classification into month-specific cutpoints useful in accounting for seasonal variation?

Do sufficient vitamin D levels at the end of summer in children and adolescents provide an assurance of vitamin D sufficiency at the end of winter? A cohort study

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