Seasonal Variation In Vitamin Research Articles

Age, Sex and Seasonal Variations of Vitamin D Level in Children of Jammu Region

Age, Sex and Seasonal Variations of Vitamin D Level in Children of Jammu Region

Seasonal Variation in Vitamin D Status among Frail Older Hospitalized Patients.

Seasonal variation in 25-hydroxyvitamin D [25(OH)D] levels is the result of sunlight dependent skin synthesis of vitamin D. However, its presence is not studied in frail older hospitalized patients. We sought to investigate whether seasonal variation in 25(OH)D levels is evident among these patients. This study investigated older participants who were consecutively admitted between February 2015 and December 2016 to the geriatric acute care ward. Results of routine measurements of 25(OH)D at hospital admission were retrospectively analyzed and stratified according to months and seasons. Previous intake of vitamin D supplementation was derived from the patients' medical records. The study group comprised 679 participants (mean age 82.1±8.2; 457 females), of which 78% had vitamin D deficiency. Older individuals not taking vitamin D supplements had a lower mean serum 25(OH)D than those receiving supplements. Of those patients with no vitamin D supplementation, 87.0% were vitamin D deficient and only 5% showing sufficient vitamin 25(OH)D. Further, there were neither monthly nor seasonal variations in vitamin 25(OH)D levels among these patients and their vitamin D levels stayed far below the recommended threshold of 20 ng/ml across the seasons. Vitamin D deficiency was very prevalent in the subgroup of older hospitalized patients without vitamin D supplementation, irrespective of season. Since no seasonal variations in mean 25(OH)D levels was observed, sunlight dependent skin synthesis is unlikely to contribute to vitamin D status in these patients. Supplementation seems to be necessary to maintain desirable vitamin D levels among this population throughout the year.

Seasonal Variation of Vitamin D Status in Long-Term Kidney Transplant Recipients

BackgroundThere is little information about circannual rhythm of vitamin D level in kidney transplantation (KTx) patients. Material and MethodsIn 71 patients (27 females; 44 males) in the long term after KTx (5.5 ± 2.6 years) during the winter and summer months plasma concentration of 25-hydroxyvitamin D (25(OH)D), 1,25-hydroxyvitamin D, parathormone (PTH), fibroblast growth factor 23 (FGF-23), calcium, and phosphorus were assessed. Vitamin D status was classified according to 25(OH)D level (ie, insufficiency, ≤30 ng/mL; deficiency, <15 ng/mL). ResultsIn this study, 96% of KTx patients had vitamin D insufficiency including 37% deficiency during winter and 89% of KTx patients had vitamin D insufficiency and 24% had vitamin D deficiency, respectively, during summer. Mean 25(OH)D level during winter was lower than in summer (17.4 ± 7.1 vs 20.2 ± 7.2 ng/mL; P = .02), similar to calcitriol (163.6 ± 37.4 vs 284.5 ± 77.8 pmol/L; P = .001). There were no significant differences in winter and summer levels of calcium, phosphorus, and PTH. The 25(OH)D level was significantly higher in patients with estimated glomerular filtration rate (eGFR) ≥45 mL/min/1.73 m2 compared with those with lower eGFR (21.6 ± 7.5 vs 17.6 ± 6.0; P = .02) only in the summer time. ConclusionsMost of the KTx patients have vitamin D insufficiency during both winter and summer with higher concentration of vitamin D metabolites in summer. Other factors than graft function may have an impact on vitamin D levels in KTx patients.

Seasonal variation in vitamin D levels and relationship with obesity in high-risk pregnant

Seasonal variation in vitamin D levels and relationship with obesity in high-risk pregnant

Seasonal variations of vitamin D and its relation to lipid profile in Iranian children and adults

BackgroundVitamin D has a multitude of functional properties and acts like a hormone in the body. Its effect on the lipid profile is one of the proposed mechanisms for its relationship with many disorders during its deficiency. But, this relationship is still conflicting and debatable, so this study was conducted to determine the association between serum level of vitamin D and lipid profiles, including serum concentrations of cholesterol, triglyceride (TG), HDL, and LDL in healthy subjects.MethodsIn this cross-sectional study, 541 volunteers with age of 5–60 years from normal and healthy subjects were selected via random sampling. Demographics and history of daily or weekly sunlight exposures were recorded. Measuring vitamin D was done in two consecutive seasons: winter and summer. Ten milliliters of peripheral venous blood sample was withdrawn after an overnight fasting. Serum levels of 25(OH) D (25, hydroxy vitamin D3) were measured using the enzyme-linked immunosorbent assay (ELISA), and the Confirmatory test was done by high-performance liquid chromatography (HPLC).ResultsMean age in the total mixed population was 30.83 ± 14.02 years. Subjects were 50.5% male and 49.5% female. Mean 25(OH) D in the total population for winter and summer were 45.8 ± 24.26 ng/ml and 55.24 ± 37.47 ng/ml respectively. In the total population, 38.08% were vitamin D deficient. Comparing serum lipid levels in the summer and winter showed a significant difference for cholesterol, LDL, and HDL, but no significant effect was found for TG. Analysis for the comparison of lipid profiles between the two genders in winter showed that there were significant differences in all lipid profiles except for LDL, while such analysis for summer revealed significant difference just for TG. In multivariate analysis, there was a significant mean difference only for LDL in subgroups with vitamin D insufficiency and deficiency. There was no correlation between Vitamin D and lipid profiles.ConclusionsVitamin D is different between the two seasons regardless of gender variations. Its status showed some significant relationship with some lipid profiles (cholesterol, LDL, and HDL) during the two seasons. There were different results among winter and summer based on the gender.

Seasonal variations in vitamin D levels in HIV-infected patients

ENWEndNote BIBJabRef, Mendeley RISPapers, Reference Manager, RefWorks, Zotero AMA Noe S, Heldwein S, Pascucci R, et al. Seasonal variations in vitamin D levels in HIV-infected patients. HIV & AIDS Review. International Journal of HIV-Related Problems. 2017;16(1):50-53. doi:10.5114/hivar.2017.65397. APA Noe, S., Heldwein, S., Pascucci, R., Oldenbüttel, C., Wiese, C., & Krosigk, A. et al. (2017). Seasonal variations in vitamin D levels in HIV-infected patients. HIV & AIDS Review. International Journal of HIV-Related Problems, 16(1), 50-53. https://doi.org/10.5114/hivar.2017.65397 Chicago Noe, Sebastian, Silke Heldwein, Rita Pascucci, Celia Oldenbüttel, Carmen Wiese, Ariane von Krosigk, and Eva Jägel-Guedes et al. 2017. "Seasonal variations in vitamin D levels in HIV-infected patients". HIV & AIDS Review. International Journal of HIV-Related Problems 16 (1): 50-53. doi:10.5114/hivar.2017.65397. Harvard Noe, S., Heldwein, S., Pascucci, R., Oldenbüttel, C., Wiese, C., Krosigk, A., Jägel-Guedes, E., Jäger, H., Wolf, E., and Spinner, C. (2017). Seasonal variations in vitamin D levels in HIV-infected patients. HIV & AIDS Review. International Journal of HIV-Related Problems, 16(1), pp.50-53. https://doi.org/10.5114/hivar.2017.65397 MLA Noe, Sebastian et al. "Seasonal variations in vitamin D levels in HIV-infected patients." HIV & AIDS Review. International Journal of HIV-Related Problems, vol. 16, no. 1, 2017, pp. 50-53. doi:10.5114/hivar.2017.65397. Vancouver Noe S, Heldwein S, Pascucci R, Oldenbüttel C, Wiese C, Krosigk A et al. Seasonal variations in vitamin D levels in HIV-infected patients. HIV & AIDS Review. International Journal of HIV-Related Problems. 2017;16(1):50-53. doi:10.5114/hivar.2017.65397.

Seasonal Variations of Vitamin D in Vegetarians

Aim: Adequate levels of vitamin D are vital for bone homeostasis throughout the life cycle, especially at older ages. We aimed to assess 25-hydroxivitamin status and seasonality variations in a sample of vegetarians stratified for age and gender. Methods: The study included 347 vegetarians, whose serums were collected between March and May (before summertime-PreS) and then between August and September (after summertime-PostS). Serum 25-hydroxyvitamin (Vitamin D) was measured by an automated immunoassay (ARCHITECT, Abbott). Results: PreS samples showed a Vitamin D median of 18.3 ng/mL and 57% resulted as deficient (<20 ng/mL) while only 13% resulted as sufficient (>30 ng/mL). The deficient fraction was the mode class at all ages. No statistically significant differences among age and sex classes were detected. PostS samples showed a Vitamin D median of 36.0 ng/mL with a significant increase of 32% as compared to PreS; 26% resulted as deficient while only 36% resulted as sufficient. In subjects aged >69 years this increase was statistically smaller than in other age groups. Mode was the sufficient class up to 49, the insufficient class (20-30 ng/mL) between 50 and 69 and the deficient class over 69 years. Conclusions: These results confirm that exposure to the sun increases the levels of vitamin D in young and middle-aged vegetarians but not in the elderly and highlight the need for dietary strategies to increase vitamin D intake especially in the older age classes.

Seasonal Variation in Vitamin D in Association with Age, Inflammatory Cytokines, Anthropometric Parameters, and Lifestyle Factors in Older Adults.

Vitamin D deficiency is present even in sunny regions. Ageing decreases pre-vitamin D production in the skin and is associated with altered cytokine profile. We performed a multivariate analysis considering lifestyle factors, anthropometric, and inflammatory markers according to seasonal variation in Mexican healthy older adults. The same cohort was followed during 12 months. Vitamin D deficiency/insufficiency was found in 91.3% of the subjects despite living in appropriate latitude (25°40′0″N). 25(OH)D levels remained below <30 ng/mL through all seasons. Vitamin D deficiency did not correlate to sun exposure or dietary intake. Gender was the strongest associated factor, explaining a variance of 20%. Waist circumference (WC) greater than 88 cm was a risk factor for vitamin D deficiency. Age (>74 years) combined with WC (>88 cm) and BMI (>32.7) showed a high probability (90%) of vitamin D deficiency. Remarkably, an increase in one centimeter in WC decreased 25(OH)D by 0.176 ng/mL, while an increase in one point BMI decreased 25(OH)D by 0.534 ng/mL. A cutoff point of 74 years of age determined probability of vitamin D hipovitaminosis. Vitamin D deficiency was correlated with TNF-α serum levels, possibly increasing the susceptibility of older adults to a proinflammatory state and its related diseases.

Seasonal Variations and Correlations between Vitamin D and Total Testosterone Levels.

BackgroundSome studies have provided evidence for a possible association between vitamin D and testosterone levels; however, the evidence from studies in Koreans is inconsistent. In addition, insufficient evidence is available to support an association between seasonal variations in vitamin D and testosterone levels in Koreans. Therefore, we aimed to investigate the association between vitamin D and testosterone levels, and between seasonal variations in these levels in Korean men.MethodsThis cross-sectional study included 1,559 men, aged 25–86 years, who underwent a medical examination. We measured serum 25-hydroxyvitamin D (25[OH]D) and total testosterone levels, and compared other laboratory test results and patient lifestyle characteristics. On the basis of sample collection time, we categorized patients into four seasons, and analyzed seasonal variability in 25(OH)D and total testosterone levels.ResultsThe average participant age (±standard deviation) was 53.3±8.8 years, and the average serum 25(OH)D and total testosterone levels were 15.9±7.0 ng/mL and 5.1±1.6 ng/mL, respectively. In the analysis of variance (ANOVA) model, no significant association was found between 25(OH)D and testosterone levels (P=0.51). ANOVA of the average 25(OH)D levels in season-based groups revealed significant seasonal variations in 25(OH)D levels (P-value for trend <0.001). No significant association was found between seasonal variations in total testosterone levels (P=0.06). However, after adjustment for confounding variables, total testosterone and 25(OH)D showed significant seasonal variability (P=0.007 and P<0.001, respectively).ConclusionWe found no significant correlation between serum 25(OH)D and total testosterone levels in Korean men. Moreover, serum 25(OH)D and total testosterone levels showed significant seasonal variations.

Seasonal Differences in Incidence and Survival of Hodgkin Lymphoma Depend on Geographic Location of Diagnosis

It has been previously described that Hodgkin lymphoma (HL) exhibits a seasonal incidence and mortality pattern. However, these findings arise from small datasets and are partially conflicting. The aim of the present study is to provide the most comprehensive analysis of seasonal variation in incidence and mortality risk of HL with a focus on geographic differences in a very large, high-quality dataset.All HL cases diagnosed between 1973 and 2012 in the 18 Surveillance, Epidemiology and End Results (SEER) registries were eligible (n=50,179). We excluded all death certificate and autopsy only cases (n=281), cases with unknown month of diagnosis (n=257), the "Alaska natives" (n=17) and "Rural Georgia" (n=57) registries due to low case numbers and cases with missing information on age at diagnosis (n=5) and Ann-arbor stage (n=8157), resulting in 41,405 cases being included in the study. All cases were grouped into quartiles according to the latitude of the case’s county (Quartile 1: <34.19°N; Quartile 2: 34.19°N to 38.05°N; Quartile 3: 38.05°N to 41.68°N; Quartile 4: ≥41.68°N). The monthly incidence was adjusted for length of month. Cosinor analysis was employed to examine seasonality of incidence in all cases, latitude quartiles and other preplanned subgroups, such as gender, histological subtype, Ann-arbor stage and decade of diagnosis. The overall mortality risk within 3 years following HL diagnosis was analyzed using a Cox proportional-hazards model with a dichotomized variable representing season of diagnosis (Winter: Sept.-Feb., Summer: Mar.-Aug.). Known risk factors were corrected for.HL exhibits a highly significant (p<0.001) seasonal incidence pattern with a peak in March and a trough in September. The adjusted incidence in September is approximately 15% higher than in March. This pattern was equally present in males (p<0.001) and females (p<0.001), but only present in the mixed cellularity (p<0.001), nodular sclerosis (p<0.001) and lymphocyte depleted subtypes (p=0.002). Seasonality was particularly pronounced in the age groups 20-29, 30-39 and 60-69, coinciding with age groups of increased HL incidence. All latitude quartiles showed significant seasonality patterns when analyzed separately, but the pattern was more pronounced in the two northern (≥38.05°N) quartiles with an amplitude of 0.102 ([0.073; 0.131], p<0.001) compared to the two southern (<38.05°N) quartiles with an amplitude of 0.055 ([0.026; 0.084], p<0.001). The difference was statistically significant (p=0.023).Considering all cases, a diagnosis in winter does not significantly increase the risk of dying compared to being diagnosed in summer (HR=1.030 [0.981; 1.081], p=0.234). However, looking at cases diagnosed in the two northern (≥38.05°N) quartiles showed an increased risk of death within 3 years after HL diagnosis (HR=1.082 [1.009; 1.161], p=0.027), whereas no such relationship was evident for cases diagnosed in the two southern (<38.05°N) latitude quartiles (HR=0.990 [0.926; 1.059], p=0.772). To further examine the relationship between latitude and excessive mortality risk after a diagnosis made in winter, we included a multiplicative interaction term between the dichotomous season of diagnosis variable and latitude. The hazard ratio for the interaction term was 1.119 ([1.009; 1.241], p=0.033) indicating a significant interaction in the way that mortality risk after a HL diagnosis in winter compared to summer is only increased at higher latitudes. All results were confirmed using 5 years of follow-up data.To conclude, HL exhibits a seasonal incidence and mortality pattern in this study, the most comprehensive analysis on this topic performed to date. The seasonal effect on the incidence of HL is exacerbated and the seasonal effect on mortality risk is only present at higher latitudes. Increased seasonal variations in Vitamin D levels at higher latitudes have been previously described. Therefore, a twofold protective effect of Vitamin D, where it both prevents HL development and increases the chance of survival after a diagnosis of HL is a possible explanation. Further studies, particularly those directly measuring Vitamin D levels in HL patients, are needed to improve the understanding of the role of Vitamin D in HL. DisclosuresEngert:Takeda, BMS: Consultancy, Honoraria, Research Funding.

Investigating the patterns and determinants of seasonal variation in vitamin D status in Australian adults: the Seasonal D Cohort Study.

BackgroundVitamin D status generally varies seasonally with changing solar UVB radiation, time in the sun, amount of skin exposed, and, possibly, diet. The Seasonal D Study was designed to quantify the amplitude and phase of seasonal variation in the serum concentration of 25-hydroxyvitamin D, (25OH)D)) and identify the determinants of the amplitude and phase and those of inter-individual variability in seasonal pattern.MethodsThe Seasonal D Study collected data 2-monthly for 12 months, including demographics, personal sun exposure using a diary and polysulphone dosimeters over 7 days, and blood for serum 25(OH)D concentration. The study recruited 333 adults aged 18–79 years living in Canberra (35°S, n = 168) and Brisbane (27°South, n = 165), Australia.DiscussionWe report the study design and cohort description for the Seasonal D Study. The study has collected a wealth of data to examine inter- and intra-individual seasonal variation in vitamin D status and serum 25(OH)D levels in Australian adults.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-016-3582-z) contains supplementary material, which is available to authorized users.

Seasonal variations in vitamin D status in indoor and outdoor female athletes

Vitamin D (VD) insufficiency is a concern, particularly among young females. The VD status shows seasonal variations, since it correlates with duration of sunlight exposure. VD insufficiency in indoor athletes is therefore suggested in winter. The aim of the present study was to determine seasonal variations in VD and bone status among indoor and outdoor female athletes. The prospective study was conducted in participants aged 20-22 years old. The participants comprised of 15 indoor and 15 outdoor athletes. The biochemical markers and bone parameters were measured in March, June, September and December. The serum 25-hydroxyvitamin D (25-OH-VD) concentration showed a seasonal oscillation, with a nadir in March (indoor, 19±4.0 ng/ml; outdoor, 32±2.7 ng/ml) and a peak in September (indoor, 32±6.6 ng/ml; outdoor, 39±5.7 ng/ml). The amplitude of oscillation was greater in the indoor compared to the outdoor athletes. Seasonal variations in serum calcium exhibited a similar pattern, while the parathyroid hormone showed an inverse pattern to serum 25-OH-VD. The nadir in bone mass, measured as speed of sound, occurred in June after peaking in December among the indoor and outdoor athletes. The pattern followed 3 months after the changes in 25-OH-VD. Indoor sports athletes are more susceptible to VD insufficiency compared to outdoor sports athletes. Insufficiency is most likely to arise in winter, and could affect bone mineralization observed 3 months after.

P447. Seasonal variations in Vitamin D concentrations in a single-centre inflammatory bowel disease series

P447. Seasonal variations in Vitamin D concentrations in a single-centre inflammatory bowel disease series

Seasonal Variation of Vitamin D in Ischemic Stroke

Seasonal Variation of Vitamin D in Ischemic Stroke

Nontuberculous Mycobacterial Disease in Children - Epidemiology, Diagnosis & Management at a Tertiary Center.

BackgroundThere are limited data on the epidemiology, diagnosis and optimal management of nontuberculous mycobacterial (NTM) disease in children.MethodsRetrospective cohort study of NTM cases over a 10-year-period at a tertiary referral hospital in Australia.ResultsA total of 140 children with NTM disease, including 107 with lymphadenitis and 25 with skin and soft tissue infections (SSTIs), were identified. The estimated incidence of NTM disease was 0.6–1.6 cases / 100,000 children / year; no increasing trend was observed over the study period. Temporal analyses revealed a seasonal incidence cycle around 12 months, with peaks in late winter/spring and troughs in autumn. Mycobacterium-avium-complex accounted for most cases (77.8%), followed by Mycobacterium ulcerans (14.4%) and Mycobacterium marinum (3.3%). Polymerase chain reaction testing had higher sensitivity than culture and microscopy for acid-fast bacilli (92.0%, 67.2% and 35.7%, respectively). The majority of lymphadenitis cases underwent surgical excision (97.2%); multiple recurrences in this group were less common in cases treated with clarithromycin and rifampicin compared with clarithromycin alone or no anti-mycobacterial drugs (0% versus 7.1%; OR:0.73). SSTI recurrences were also less common in cases treated with two anti-mycobacterial drugs compared with one or none (10.5% versus 33.3%; OR:0.23).ConclusionsThere was seasonal variation in the incidence of NTM disease, analogous to recently published observations in tuberculosis, which have been linked to seasonal variation in vitamin D. Our finding that anti-mycobacterial combination therapy was associated with a reduced risk of recurrences in patients with NTM lymphadenitis or SSTI requires further confirmation in prospective trials.

Seasonal effect of vitamin D deficiency in patients with acute myocardial infarction.

Vitamin D is a major regulator of mineral bone metabolism. The lower vitamin D levels in patients with acute myocardial infarction (AMI) and the seasonal variation of vitamin D levels are proposed. The evaluation of the seasonal relationship of 25(OH)D levels in patients with AMI and analysis of confounding factors (gender or diabetes mellitus) affecting the levels of vitamin D in AMI patients. Fifty-nine consecutive patients with mean age 58 ± 9.4 years were admitted to the Department of Invasive Cardiology. Subjects had diagnosed uncomplicated myocardial infarction. Blood samples for analysis were collected on patient admission to the cardiac unit after heparin treatment. Samples for routine laboratory tests were immediately processed. For 25(OH)D, the 25-hydroxycholecalciferol test, which measures total vitamin D levels in serum (DRG Instruments GmbH, Marburg, Germany), was applied. Median serum 25(OH)D concentration in AMI patients was below the recommended optimal values 7.1 (2.3-13.3) ng/mL. Fifty-three (89.8%) patients had vitamin D deficiency (VDD) below 20 ng/mL, six (10.2%) patients had suboptimal 25(OH)D levels (between 20 ng/mL and 30 ng/mL), and no one had the recommended reference range. The seasonal effect of 25(OH)D variations among AMI patients was observed with the lowest levels in the beginning of the year (January-March) and the highest levels at the end of the year (September-December) (p = 0.007). Patients with normoglycaemia had significantly higher (9.2 [2.3-16.8] ng/mL) vitamin D levels compared to patients with impaired glucose tolerance (2.3 [2.3-3.9] ng/mL) or diabetes mellitus (8.5 [2.5-13.3] ng/mL) (p = 0.01). A high prevalence of VDD in AMI patients has been confirmed. Supplementation of vitamin D in AMI patients with hyperglycaemia can bring greater benefits.

Serum levels of 25(OH)D are not associated with venous thromboembolism in the elderly population. A case-control study.

The prevalence of both vitamin D deficiency and venous thromboembolism (VTE) is important in the elderly. Previous studies have provided evidence for a possible association between vitamin D status and the risk of VTE. Thus, we aimed to investigate the association between vitamin D levels and VTE in the population aged 75 and over included in the EDITH case-control study. The association between vitamin D status and VTE was analysed. We also analysed the monthly and seasonal variations of VTE and vitamin D. Between May 2000 and December 2009, 340 elderly patients (mean age 81.5 years, 32% men) with unprovoked VTE and their controls were included. The univariate and multivariate analysis found no significant association between serum levels of vitamin D and the risk of unprovoked VTE. In the unadjusted analysis, a higher BMI was statistically associated with an increased risk of VTE (OR 1.09; 95% CI 1.05-1.13) whereas a better walking capacity and living at home were associated with a decreased rate of VTE: OR 0.57; 95% CI 0.36-0.90 and 0.40; 95% CI 0.25-0.66, respectively. Although not significant, more VTE events occurred during winter (p=0.09). No seasonal variations of vitamin D levels were found (p=0.11). In conclusion, in contrast with previous reports our findings suggest that vitamin D is not associated with VTE in the elderly population.

Seasonal variation of vitamin D levels in Swiss athletes

Introduction: Vitamin D deficiency is very prevalent in world population and growing evidence shows that also athletes are affected. Vitamin D deficiency causes beside bone disorders, musculoskeletal pain, muscle weakness and is associated with many other health disorders. For athletes in particular it may impair training and performance, prolong recovery and increase risk of injury. We therefore analyzed vitamin D levels in Swiss athletes focusing on prevalence according to age, gender, seasonal variations, indoor or outdoor sports, sunscreen use and vitamin D supplementation. Methods: This study was performed in a convenient sample of 655 Swiss Olympic athletes over one year. Blood samples were obtained and a questionnaire was filled in at Swiss Olympic Medical Centers or Bases during an annual routine exam. Data were then sent to the central laboratory of the Aarau hospital where they were processed and sent to us in an anonymized version. Vitamin D levels were categorized into deficiency (≤ 50 nmol/l), insufficiency (between 50 and 75 nmol/l) and adequate levels (&gt; 75 nmol/l) of 25-hydroxyvitamin D. By means of the questionnaire, we assessed age, gender, type of sport, symptoms possibly related to vitamin D deficiency during the last year, frequency of sunscreen use and vitamin D-containing medications of the athletes. Results: 13.5% of the participants (total number = 651) presented a vitamin D deficiency, 37.8% a vitamin D insufficiency so that more than half of the athletes (51.2%) had inadequate vitamin D levels. Inadequate vitamin D levels were more prevalent in younger athletes, during seasons with lower sun exposure, in indoor sports during the sun deprived seasons, in athletes without vitamines supplementation and in athletes of lower Swiss Olympic classes compared to their counterparts. Conclusions: The results of the study show that the prevalence of inadequate vitamin D levels in Swiss athletes is substantial for younger athletes (&lt; 18 years of age) and for indoor athletes during sun deprived periods of the year. However, a general vitamin supplementation containing vitamin D reduced the prevalence of vitamin D inadequacy which is especially relevant during sun deprived seasons.

BMI and season are associated with vitamin D deficiency in women with impaired fertility: a two-centre analysis.

Animal and human studies suggest that vitamin D regulates functions of the reproductive system. Vitamin D deficiency is prevalent in women of reproductive age. Vitamin D status has been associated with in vitro fertilisation outcome, features of polycystic ovarian syndrome (PCOS) and endometriosis. The aims of our study were to investigate the prevalence of vitamin D deficiency of infertile women living in central Germany, to identify risk factors for vitamin D deficiency and to specify seasonal variations of vitamin D status. This was a retrospective cohort study at an academic tertiary care centre (N = 113) and an Outpatient Centre for Reproductive Medicine (N = 193) of women presenting for infertility treatment. The statistical evaluation was descriptive and explorative. Possible risk factors associated with an increased risk for vitamin D deficiency were assessed using multiple logistic regression models. Variables with p value less than 0.05 were further assessed in a multivariable logistic regression model. Overall, 98.2 % of patients at centre 1 and 81.3 % of women with impaired fertility at centre 2 had deficient or insufficient vitamin D levels. Overweight BMI and limited exposure to sun (winter, spring and autumn trimester) were associated with an increased risk of vitamin D deficiency. Vitamin D levels did not vary according to age or infertility associated disorders (e.g. endometriosis, PCOS). The rate of vitamin D deficiency among women with impaired fertility is alarming. Prospective studies are pressingly needed to confirm a causal relationship and to investigate the potential therapeutic benefits of vitamin D supplementation in this population.

Seasonal variations in vitamin D in relation to growth in short prepubertal children before and during first year growth hormone treatment.

This study investigated the relationship between seasonal variations in 25-hydroxyvitamin D (25(OH)D) levels and growth in prepubertal children during both the pretreatment year and the first year of GH treatment. The study included 249 short prepubertal children with a broad range of GH secretion, GH(max) during a 24 h profile median 23; range 1-127 mU/L, 191 boys (mean age ± SD, 8.6 ± 2.6 years), 58 girls (7.5 ± 1.9 years) receiving GH treatment (mean 43 µg/kg/day; range 17-99 µg/kg/day). Serum 25(OH)D was measured using an automated IDS-iSYS immunoassay. 25(OH)D levels showed seasonal variation, and decreased significantly during GH treatment. 25(OH)D levels at start and first year reduction in 25(OH)D, correlated (-) with the first year growth response during treatment. The degree of GH secretion capacity within our study population of mainly non-GH deficient children and 25(OH)D sufficient (67 ± 29 nmol/L) had no influence on 25(OH)D levels. Growth during GH treatment were independent of seasonal variations in 25(OH)D. Multiple regression analysis showed that 25(OH)D levels at treatment start, together with auxological data and IGF-binding protein-(3)SDS, explained 61 % of the variation in first year gain in heightSDS. 25(OH)D levels were associated with first year growth response to GH and may be a useful contribution to future growth prediction models.