Greater seasonal cycling of 25-hydroxyvitamin D is associated with increased parathyroid hormone and bone resorption

Life history in primate teeth is revealed by changes in major and minor element concentrations measured via field-emission SEM-EDS analysis

Overcoming the non-specificity of histological accentuated growth lines in hard tissues is an ongoing challenge. Identifying season at death and reproductive events has profound implications for evolutionary, ecological and conservation studies. Dental cementum is a mineralized tissue with yearly periodicity that continues deposition from tooth formation until death, maintaining a record spanning almost the entire life of an individual. Recent work has successfully employed elemental analysis of calcified incremental tissues to detect changes in extrinsic conditions such as diet and climate and to identify two important life-history milestones: weaning and sexual maturity. Here, we employ field-emission scanning electron microscopy and energy-dispersive X-ray analysis to measure the relative concentrations of calcium, phosphorous, oxygen, magnesium and sodium in the cementum of 34 teeth from seven male and female rhesus macaques with known medical and life-history information. We find that changes in relative magnesium concentrations correspond with reproductive events in females and breastfeeding in infants. Additionally, we observe seasonal calcium patterns in 77.3% of the samples.

Bone Turnover Markers: Basic Biology to Clinical Applications

Bone turnover markers (BTMs) are used widely, in both research and clinical practice. In the last 20 years, much experience has been gained in measurement and interpretation of these markers, which include commonly used bone formation markers bone alkaline phosphatase, osteocalcin, and procollagen I N-propeptide; and commonly used resorption markers serum C-telopeptides of type I collagen, urinary N-telopeptides of type I collagen and tartrate resistant acid phosphatase type 5b. BTMs are usually measured by enzyme-linked immunosorbent assay or automated immunoassay. Sources contributing to BTM variability include uncontrollable components (e.g., age, gender, ethnicity) and controllable components, particularly relating to collection conditions (e.g., fasting/feeding state, and timing relative to circadian rhythms, menstrual cycling, and exercise). Pregnancy, season, drugs, and recent fracture(s) can also affect BTMs. BTMs correlate with other methods of assessing bone turnover, such as bone biopsies and radiotracer kinetics; and can usefully contribute to diagnosis and management of several diseases such as osteoporosis, osteomalacia, Paget's disease, fibrous dysplasia, hypophosphatasia, primary hyperparathyroidism, and chronic kidney disease-mineral bone disorder.

Lack of significant seasonal association between serum 25(OH)D concentration, muscle mass and strength in postmenopausal women from the D-FINES longitudinal study

The aim of the present study was to assess the seasonal relationship between serum 25(OH)D concentration, lean mass and muscle strength. This was a secondary data analysis of a subgroup of 102 postmenopausal women participating in the 2006-2007 D-FINES (Vitamin D, Food Intake, Nutrition and Exposure to Sunlight in Southern England) study. The cohort was assessed as two age subgroups: <65 years (n=80) and ≥65 years (n=22). Outcome measures included lean mass (DXA), muscle strength (handgrip dynamometry) and serum 25(OH)D concentration (enzymeimmunoassay). Derived outcomes included appendicular skeletal muscle mass (ASM) and relative appendicular skeletal muscle index (RASM). Sarcopenia status was assessed using the European Working Group on Sarcopenia in Older People 2018 criteria. Non-parametric partial correlation using BMI as a covariate was used to evaluate the study aims. There were no statistically significant associations between total lean mass, ASM or RASM and 25(OH)D in any group at any season. There was a trend for handgrip strength to be positively associated with serum 25(OH)D concentration. There was a trend showing a higher prevalence of sarcopenia in women ≥65 years. Sarcopenia status appeared transient for five women. In conclusion, the present study found no significant association between vitamin D status and functional indicators of musculoskeletal health, which were additionally not affected by season.

Global differences in vitamin D status and dietary intake: a review of the data

BACKGROUND

Internationally, concern has been repeatedly raised about the little notable progress in the collection, analysis and use of population micronutrient status and deficiency data globally. The need for representative status and intake data for vitamin D has been highlighted as a research priority for well over a decade.

AIM AND METHODS

A narrative review which aims to provide a summary and assessment of vitamin D nutritional status data globally. This review divides the world into the Food and Agriculture Organisation's (FAO) major regions: the Americas, Europe, Oceania, Africa and Asia. Emphasis was placed on published data on the prevalence of serum 25-hydroxyvitamin D (25(OH)D) < 25/30 and <50 nmol/L (reflecting vitamin D deficiency and inadequacy, respectively) as well as vitamin D intake, where possible from nationally representative surveys.

RESULTS

Collating data from the limited number of available representative surveys from individual countries might suggest a relatively low overall prevalence of vitamin D deficiency in South America, Oceania and North America, whereas there is more moderate prevalence in Europe and Asia, and possibly Africa. Overall, the prevalence of serum 25(OH)D < 25/30 and <50 nmol/L ranges from ~5 to 18% and 24 to 49%, respectively, depending on FAO world region. Usual intakes of vitamin D can also vary by FAO world region, but in general, with a few exceptions, there are very high levels of inadequacy of vitamin D intake.

CONCLUSIONS

While the burden of vitamin D deficiency and inadequacy varies by world regions and not just by UVB availability, the global burden overall translates into enormous numbers of individuals at risk.

Non-classical effects of vitamin D: Non-bone effects of vitamin D

Our understanding of vitamin D has improved considerably in recent years. The role of vitamin D in preventing osteoporotic fractures is now well-established. However, an important controversy has emerged in the last decade concerning the effects of the active form of vitamin D (1,25-dihydroxy-vitamin D) on tissues other than bone (non-classical effects). The demonstration that the vitamin D receptor (VDR) is ubiquitously, expressed combined with increasing observational data supporting a relationship between the level of 25-hydroxy-vitamin D in the serum and chronic metabolic disorders, cardiovascular disease and neoplasms, have led to its redefinition as a steroid hormone and the proposal of its use in preventing and/or treating those diseases. This article is an update on the different non-bone or non-classical effects of "vitamin-hormone D", and its potential preventive or therapeutic role in certain diseases, however, this review is not exhaustive. The different modalities of substitution or supplementation proposed in France by the Groupe de Recherche et d'Information sur les Ostéoporoses (GRIO) are also summarised.

Vitamin D supplementation: cholecalciferol, calcifediol, and calcitriol

The specific compound that is meant for use in the context of vitamin D supplementation is often ambiguous. The term "supplementation" has been used in the context of cholecalciferol, ergocalciferol, calcidiol, and calcitriol. In nature, by far the major form of vitamin D that nurtures the body is cholecalciferol. In contrast, ergocalciferol is primarily a synthetic and less stable product which is less potent per microgram dose than is cholecalciferol. Calcidol is the major circulating metabolite of cholecalciferol, while calcitriol is the hormone that upregulates the active transport of calcium from the gut, and which suppresses parathyroid hormone secretion. Nutrition policy papers and guidelines leave unstated the obvious fact that calcidiol and calcitriol are not nutrients, and that those metabolites are not pertinent to food fortification or dietary supplementation. Recent evidence shows that ergocalciferol is not stable with storage, and it is far more susceptible to breakdown with cooking and baking than is cholecalciferol. Therefore, it must be concluded that cholecalciferol is the only form of vitamin D that should be considered in the context of the nutritional functions of fortification and supplementation.

Serum Vitamin D Level Does not Affect The Sensitivity of Parathyroid Adenoma Localization Tests

The aim of the present study was to evaluate the predictive value of 25-hydroxyvitamin D, calcium and parathormone level, co-existence of thyroid nodule, thyroidectomy history and adenoma volume on the success of neck ultrasound (US) and technetium-99m sestamibi (MIBI) scan in primary hyperparathyroidism (PHP) patients. This study included 256 patients with PHP who underwent parathyroidectomy. 169 (%66) patients had vitamin D deficiency and 56 (%22) of patients had insufficiency. The sensitivity of US and MIBI studies showed no difference between vitamin D deficiency, insufficiency and replete groups (%80.5, %82 and %71 (p > 0.05) and %81, %84 and %71 respectively (p > 0.05)). Vitamin D level was not found to be an independent predictor of localization on either US or MIBI scan after adjusting for different variables (p > 0.05). Calcium level was found to be an independent predictor for US sensitivity (r²:0,033, p:0,032) and parathormone level for MIBI sensitivity (r²:0,05, p:0,025). The co-existence of nodular thyroid disease and history of thyroidectomy significantly decreased the sensitivity of US (%76 and %43). MIBI sensitivity was not impaired by nodular disease but the history of thyroidectomy also impaired the sensitivity of MIBI (%43). As a result vitamin D level does not affect the sensitivity of preoperative localization tests.

The Prevalence of Vitamin D Deficiency and the Determinants of 25(OH)D Concentration in Older Irish Adults: Data From The Irish Longitudinal Study on Ageing (TILDA)

Background

Few data are available examining the determinants of vitamin D status exclusively in older adults. We aimed to investigate the prevalence and determinants of vitamin D deficiency in a representative sample of the older Irish population (aged 50-98 years).

Methods

The concentration of 25-hydroxyvitamin D (25(OH)D) was measured in 5,356 community-dwelling older Irish adults from The Irish Longitudinal Study on Ageing (TILDA). Detailed demographic, geographic, lifestyle, and socioeconomic factors were assessed by questionnaire. Proportions of deficiency prevalence were generated by season sampled. Linear regression was used to investigate the association between 25(OH)D concentration and reported risk factors.

Results

The prevalence of deficiency (25(OH)D < 30 nmol/L) was 13.1% (95% CI: 12.1-14.2). Deficiency status was more prevalent in nonsupplement users, in winter, in smokers, in obese adults, the physically inactive, those living alone, and in the oldest old (>80 years). The main predictors (p < .05) of 25(OH)D concentration were supplement use (coefficient nmol/L: 27.2 [95% CI: 15.3-39.2]), smoking (-8.9 [-12.6--5.2]), summer season (5.9 [2.7-9.1]), and obesity (-4.0 [-6.3--1.7]).

Conclusion

Vitamin D deficiency is common among older Irish adults. These data indicate the need for targeted strategies within sections of the older population to improve vitamin D status.

Serum 25-hydroxyvitamin D fluctuations in military personnel during 6-month summer operational deployments in Afghanistan

Soldier operational performance is determined by their fitness, nutritional status, quality of rest/recovery, and remaining injury/illness free. Understanding large fluctuations in nutritional status during operations is critical to safeguarding health and well-being. There are limited data world-wide describing the effect of extreme climate change on nutrient profiles. This study investigated the effect of hot-dry deployments on vitamin D status (assessed from 25-hydroxyvitamin D (25(OH)D) concentration) of young, male, military volunteers. Two data sets are presented (pilot study, n 37; main study, n 98), examining serum 25(OH)D concentrations before and during 6-month summer operational deployments to Afghanistan (March to October/November). Body mass, percentage of body fat, dietary intake and serum 25(OH)D concentrations were measured. In addition, parathyroid hormone (PTH), adjusted Ca and albumin concentrations were measured in the main study to better understand 25(OH)D fluctuations. Body mass and fat mass (FM) losses were greater for early (pre- to mid-) deployment compared with late (mid- to post-) deployment (P<0·05). Dietary intake was well-maintained despite high rates of energy expenditure. A pronounced increase in 25(OH)D was observed between pre- (March) and mid-deployment (June) (pilot study: 51 (sd 20) v. 212 (sd 85) nmol/l, P<0·05; main study: 55 (sd 22) v. 167 (sd 71) nmol/l, P<0·05) and remained elevated post-deployment (October/November). In contrast, PTH was highest pre-deployment, decreasing thereafter (main study: 4·45 (sd 2·20) v. 3·79 (sd 1·50) pmol/l, P<0·05). The typical seasonal cycling of vitamin D appeared exaggerated in this active male population undertaking an arduous summer deployment. Further research is warranted, where such large seasonal vitamin D fluctuations may be detrimental to bone health in the longer-term.

Vitamin D supplement use and associated demographic, dietary and lifestyle factors in 8024 South Asians aged 40-69 years: analysis of the UK Biobank cohort

OBJECTIVE

Vitamin D deficiency (serum 25-hydroxyvitamin D<25nmol/L) is extremely common in western-dwelling South Asians but evidence regarding vitamin D supplement usage in this group is very limited. This work identifies demographic, dietary and lifestyle predictors associated with vitamin D supplement use.

DESIGN

Cross-sectional analysis of baseline vitamin D supplement use data.

SETTING

UK Biobank cohort.

SUBJECTS

In total, n 8024 South Asians (Bangladeshi, Indian, Pakistani), aged 40-69 years.

RESULTS

Twenty-three % of men and 39% of women (P<0.001) [22% of Bangladeshis, 32% of Indians, 25% of Pakistanis (P<0.001)] took a vitamin D containing supplement. Median vitamin D intakes from diet were low at 1.0-3.0 micrograms per day, being highest in Bangladeshis and lowest in Indians (P<0.001). Logistic regression modelling showed that females had a higher odds of vitamin D supplement use than males (odds ratio (OR) = 2.02; 95% confidence interval (CI) 1.79 to 2.28). A lower supplement usage was seen in younger persons (40-60 years) (OR=0.75; 95% CI 0.65 to 0.86 reference= >60 years), and those living outside of Greater London (OR=0.53 to 0.77), with borderline trends for a lower body mass index, higher oily fish intake and higher household income associated with increased odds of vitamin D supplement use.

CONCLUSIONS

Vitamin D supplements were not used by most South Asians and intakes from diet alone are likely to be insufficient to maintain adequate vitamin D status. Public health strategies are now urgently required to promote the use of vitamin D supplements in these specific UK South Asian subgroups.

High bone mineral density in sickle cell disease: Prevalence and characteristics

BACKGROUND

Osteosclerosis (OSC) is a rarely studied complication of sickle cell disease (SCD). The objective of our study was to determine the prevalence and characteristics of high bone mineral density (BMD) and its radiological features in adult SCD patients.

METHODS

This prospective observational study was conducted from May 2007 to May 2016 in consecutive patients with steady-state SCD at two university hospitals. The BMD of the lumbar spine (L1-L4) and right femoral neck was determined by dual energy X-ray absorptiometry. Clinical, laboratory and radiographic data were recorded. High BMD was defined as a BMD Z-score of at least +2.5 standard deviations at the lumbar spine or hip. The characteristics of the patients with high BMD were compared to those of individuals with low or middle BMD, using multivariate ordinal logistic regression.

RESULTS

135 patients (86 women and 49 men) with a median age of 27 (IQR 23-33) years were included. High BMD was diagnosed in 20 (15%) patients with a median age of 33.5 (IQR 28-45) years. The SCD genotypes of these patients were SS in 11, SC in 5, S/beta+ in 3, and S/beta0 in 1. High BMD patients more frequently harbored the S/beta SCD genotype (21% vs 5% in non-high BMD patients; p=0.047) and were older (p=0.0007). Compared to patients with low or middle BMD, after adjustment for age and SCD genotype, high BMD patients had a higher prevalence of avascular necrosis history (p=0.009), higher BMI (p=0.007), and lower serum resorption marker CTX (p=0.04), bilirubin (p=0.02) and parathyroid hormone levels (p=0.02). There were no differences between groups regarding fracture history, H-shaped vertebrae or other biological variables.

CONCLUSION

High-BMD values is a common manifestation in SCD patients, especially in those with the S/beta-thalassemia genotypes. The prevalence of high-BMD in SCD is associated with older age, suggesting that it will be more common in the future because the life span of patients with SCD is increasing thanks to significant progress in SCD treatment.

Vitamin D levels and parathyroid hormone variations of children living in a subtropical climate: a data mining study

BACKGROUND

Vitamin D and intact parathyroid hormone (iPTH) play a crucial role in calcium homeostasis and bone health of children. Serum level of 25-hydroxyvitamin D (25-OHD) is considered to be the most accurate marker for vitamin D status. However, there have only been a few studies, with limited number of subjects, investigating the relationship between 25-OHD and parathyroid hormone (PTH) in children. The aim of this study was to evaluate the seasonal 25-OHD levels and its associations with intact parathyroid hormone (iPTH) in Turkish children at all pediatric ages; and then to define a critical decision threshold level for 25-OHD deficiency in Turkish children.

METHODS

A retrospective record review of 90,042 children, was performed on serum 25-OHD and for 3525 iPTH levels. They were measured by mass spectrometry method and by electrochemiluminescence immunoassay simultaneously.

RESULTS

25-OHD levels showed a sinusoidal fluctuation througout the year; being significantly higher in summer and autumn (p < 0,01). 25-OHD levels decreased with respect to age. The significant inverse relationship that was found between iPTH and 25-OHD suggests that the inflection point of serum 25-OHD level for maximal suppression of PTH is at 30 ng/ml.

CONCLUSION

As the rate of vitamin D deficiency decreases in the early years due to vitamin D supplementation, the recommendation should be set due to a clinical threshold level of 30 ng/ml for 25-OHD based on PTH levels in children of our population.

Maternal Vitamin D Status and the Relationship with Neonatal Anthropometric and Childhood Neurodevelopmental Outcomes: Results from the Seychelles Child Development Nutrition Study

Vitamin D has an important role in early life; however, the optimal vitamin D status during pregnancy is currently unclear. There have been recent calls for pregnant women to maintain circulating 25-hydroxyvitamin D (25(OH)D) concentrations >100 nmol/L for health, yet little is known about the long-term potential benefits or safety of achieving such high maternal 25(OH)D concentrations for infant or child health outcomes. We examined maternal vitamin D status and its associations with infant anthropometric and later childhood neurocognitive outcomes in a mother-child cohort in a sun-rich country near the equator (4.6° S). This study was conducted in pregnant mothers originally recruited to the Seychelles Child Development Nutrition Study. Blood samples (n = 202) taken at delivery were analysed for serum 25-hydroxyvitamin D (25(OH)D) concentrations. Multiple linear regression models assessed associations between maternal 25(OH)D and birth weight, infant head circumference, and neurocognitive outcomes in the children at age 5 years. Mothers were, on average, 27 years of age, and the children’s average gestational age was 39 weeks. None of the women reported any intake of vitamin D supplements. Maternal 25(OH)D concentrations had a mean of 101 (range 34–218 nmol/L) and none were deficient (<30 nmol/L). Maternal 25(OH)D concentrations were not associated with child anthropometric or neurodevelopmental outcomes. These findings appear to indicate that a higher vitamin D status is not a limiting factor for neonatal growth or neurocognitive development in the first 5 years of life. Larger studies with greater variability in vitamin D status are needed to further explore optimal cut-offs or non-linear associations (including for maternal health) that might exist among populations with sub-optimal exposure.

Higher bone resorption excretion in South Asian women vs. White Caucasians and increased bone loss with higher seasonal cycling of vitamin D: Results from the D-FINES cohort study

Few data exist on bone turnover in South Asian women and it is not well elucidated as to whether Western dwelling South Asian women have different bone resorption levels to that of women from European ethnic backgrounds. This study assessed bone resorption levels in UK dwelling South Asian and Caucasian women as well as evaluating whether seasonal variation in 25-hydroxyvitamin D [25(OH)D] is associated with bone resorption in either ethnic group. Data for seasonal measures of urinary N-telopeptide of collagen (uNTX) and serum 25(OH)D were analysed from n=373 women (four groups; South Asian postmenopausal n=44, South Asian premenopausal n=50, Caucasian postmenopausal n=144, Caucasian premenopausal n=135) (mean (±SD) age 48 (14) years; age range 18-79years) who participated in the longitudinal D-FINES (Diet, Food Intake, Nutrition and Exposure to the Sun in Southern England) cohort study (2006-2007). A mixed between-within subjects ANOVA (n=192) showed a between subjects effect of the four groups (P<0.001) on uNTX concentration, but no significant main effect of season (P=0.163). Bonferroni adjusted Post hoc tests (P≤0.008) suggested that there was no significant difference between the postmenopausal Asian and premenopausal Asian groups. Season specific age-matched-pairs analyses showed that in winter (P=0.04) and spring (P=0.007), premenopausal Asian women had a 16 to 20nmolBCE/mmol Cr higher uNTX than premenopausal Caucasian women. The (amplitude/mesor) ratio (i.e. seasonal change) for 25(OH)D was predictive of uNTX, with estimate (SD)=0.213 (0.015) and 95% CI (0.182, 0.245; P<0.001) in a non-linear mixed model (n=154). This showed that individuals with a higher seasonal change in 25(OH)D, adjusted for overall 25(OH)D concentration, showed increased levels of uNTX. Although the effect size was smaller than for the amplitude/mesor ratio, the mesor for 25(OH)D concentration was also predictive of uNTX, with estimate (SD)=-0.035 (0.004), and 95% CI (-0.043, -0.028; P<0.001). This study demonstrates higher levels of uNTX in premenopausal South Asian women than would be expected for their age, being greater than same-age Caucasian women, and similar to postmenopausal Asian women. This highlights potentially higher than expected bone resorption levels in premenopausal South Asian women which, if not offset by concurrent increased bone formation, may have future clinical and public health implications which warrant further investigation. Individuals with a larger seasonal change in 25(OH)D concentration showed an increased bone resorption, an association which was larger than that of the 25(OH)D yearly average, suggesting it may be as important clinically to ensure a stable and steady 25(OH)D concentration, as well as one that is high enough to be optimal for bone health.

Special considerations for vitamin D in the south Asian population in the UK

The human requirement for vitamin D is achieved primarily through the synthesis of this prehormone in the skin during exposure to ultraviolet B (UVB) radiation, with only a minor contribution from the diet, year round. Achieving optimal vitamin D status is therefore largely dependent upon adequate exposure of the skin to sunlight, however, the length of exposure required varies with latitude and season, and is also dependent upon skin pigmentation, with darker skin requiring greater exposure than fair skin due to the protective effects of melanin against UVB radiation. In northern European latitudes, where UVB radiation between the months of October and March is of insufficient intensity for the synthesis of vitamin D via this route, vitamin D deficiency is a public health concern, particularly for south Asian diaspora and other dark-skinned ethnic minority communities. The consequences of vitamin D deficiency include poor bone health, including rickets and osteomalacia. In addition, there is increasing awareness of an important role for vitamin D in the development and progression of chronic diseases, including type 2 diabetes, which is prevalent in south Asian populations. The aim of this review is to examine some of the most recent reports of vitamin D status in south Asian diaspora communities, and to explore its impact on bone health. In addition, we will examine the putative association between type 2 diabetes and vitamin D deficiency in south Asian populations and the current guidelines for treatment of vitamin D deficiency of south Asians in primary care settings.

The relationship between vitamin D status and muscle strength in young healthy adults from sunny climate countries currently living in the northeast of Scotland

The current study examined the relationship between vitamin D status and muscle strength in young healthy adults: residents (>6 months) and newcomers (0-3 months), originally from sunny climate countries but currently living in the northeast of Scotland. Our longitudinal data found a positive, albeit small, relationship between vitamin D status and knee extensor isometric strength.

INTRODUCTION

Vitamin D has been suggested to play a role in muscle health and function, but studies so far have been primarily in older populations for falls prevention and subsequent risk of fractures.

METHODS

Vitamin D status was assessed in a healthy young adults from sunny climate countries (n = 71, aged 19-42 years) with 56% seen within 3 months of arriving in Aberdeen [newcomers; median (range) time living in the UK = 2 months (9-105 days)] and the remainder resident for >6 months [residents; 23 months (6-121 months)]. Participants attended visits every 3 months for 15 months. At each visit, fasted blood samples were collected for analysis of serum 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), carboxy-terminal collagen crosslinks (CTX) and N-terminal propeptide of type I collagen (P1NP). Maximal voluntary contractions (MVC) were performed for grip strength (both arms) and for maximal isometric strength of the knee extensors (right knee).

RESULTS

There were small seasonal variations in 25(OH)D concentrations within the newcomers and residents, but no seasonal variation in bone turnover markers. There was a positive, albeit small, association between 25(OH)D and knee extensor maximal isometric strength. Mixed modelling predicted that for each 1 nmol/L increase in 25(OH)D, peak torque would increase by 1 Nm (p = 0.04).

CONCLUSIONS

This study suggests that vitamin D may be important for muscle health in young adults migrating from sunnier climates to high latitudes, yet the potential effect is small.

Analysis of Changes in Parathyroid Hormone and 25 (OH) Vitamin D Levels with Respect to Age, Gender and Season: A Data Mining Study

BACKGROUND

25 (OH) vitamin D3 (25(OH)D) and parathyroid hormone (PTH) are important regulators of calcium homeostasis. The aim of this study was to retrospectively determine the cut-off for sufficient 25(OH)D in a four-season region and the influence of age, seasons, and gender on serum 25(OH)D and PTH levels.

METHODS

Laboratory results of 9890 female and 2723 male individuals aged 38.8±22.1 years who had simultaneous measurements of 25(OH)D and PTH were retrospectively analyzed by statistical softwares. Serum 25(OH)D and PTH levels were measured by a mass spectrometry method and by an electrochemiluminescence immunoassay, respectively.

RESULTS

Mean serum 25(OH)D levels showed a sinusoidal fluctuation throughout the year and were significantly (p<0.01) higher in summer and autumn. On the other hand, PTH levels were significantly higher (p<0.01) in women and showed an opposite response to seasonal effects relative to 25(OH)D. Lowest levels of 25(OH)D were detected in people aged between 20 and 40 years whereas PTH hormone levels were gradually increasing in response to aging. The significant exponential inverse relationship that was found between PTH and 25(OH)D (PTH=exp(4.12-0.064*sqrt(25(OH)D)) (r=-0.325, R- squared=0.105, p<0.001)) suggested that the cut-off for sufficient 25(OH)D should be 75 nmol/L.

CONCLUSIONS

Our retrospective study based on large data set supports the suitability of the currently accepted clinical cut-off of 75 nmol/L for sufficient 25(OH)D. However, the issue of assessing Vitamin D deficiency remains difficult due to seasonal variations in serum 25(OH)D. Therefore, PTH measurements should complement 25(OH)D results for diagnosing Vitamin D deficiency. It is imperative that seasonally different criteria should be considered in future.

Prediction of winter vitamin D status and requirements in the UK population based on 25(OH) vitamin D half-life and dietary intake data

On a population basis, there is a gradual decline in vitamin D status (plasma 25(OH)D) throughout winter. We developed a mathematical model to predict the population winter plasma 25(OH)D concentration longitudinally, using age-specific values for 25(OH)D expenditure (25(OH)D₃t_1/2), cross-sectional plasma 25(OH)D concentration and vitamin D intake (VDI) data from older (70+ years; n=492) and younger adults (18-69 years; n=448) participating in the UK National Diet and Nutrition Survey. From this model, the population VDI required to maintain the mean plasma 25(OH)D at a set concentration can be derived. As expected, both predicted and measured population 25(OH)D (mean (95%CI)) progressively declined from September to March (from 51 (40-61) to 38 (36-41)nmol/L (predicted) vs 38 (27-48)nmol/L (measured) in older people and from 59 (54-65) to 34 (31-37)nmol/L (predicted) vs 37 (31-44)nmol/L (measured) in younger people). The predicted and measured mean values closely matched. The predicted VDIs required to maintain mean winter plasma 25(OH)D at 50nmol/L at the population level were 10 (0-20) to 11 (9-14) and 11 (6-16) to 13(11-16)μg/d for older and younger adults, respectively dependent on the month. In conclusion, a prediction model accounting for 25(OH)D₃t_1/2, VDI and scaling factor for the 25(OH)D response to VDI, closely predicts measured population winter values. Refinements of this model may include specific scaling factors accounting for the 25(OH)D response at different VDIs and as influenced by body composition and specific values for 25(OH)D₃ t_1/2 dependent on host factors such as kidney function. This model may help to reduce the need for longitudinal measurements.

Seasonal changes in serum calcium, PTH and vitamin D levels in patients with primary hyperparathyroidism

BACKGROUND

Seasonal variations of 25-hydroxyvitamin D, PTH and calcium levels are not well characterized in primary hyperparathyroidism (PHPT). Our objectives were to characterize seasonal changes in these parameters in PHPT patients, and to assess whether these seasonal changes affect clinical decision making.

METHODS

This is a retrospective study based on the electronic medical records of Clalit Health service in the south of Israel between 2000 and 2012. Patients 18years and older with PHPT (PTH>upper limit of norm (ULN) and serum calcium>10.5mg%) were included. Patients with renal failure or on Thiazide diuretics were excluded. All serum levels of calcium, PTH and 25-hydroxyvitamin D were collected and then stratified according to season.

RESULTS

792 patients were classified as PHPT (72.2% female) and had a total of 2659 PTH tests, 1395 25-hydroxyvitamin D tests and 7426 calcium test. Fifty six percent of 25-hydroxyvitamin D levels were <50nmol/L. Seasonality was demonstrated in all three parameters: mean 25-hydroxyvitamin D was 13% higher in the summer compared to the winter (P<0.001), median PTH values showed opposite trend with a fall of about 8.4% in summer compared to winter (P<0.001). Calcium levels were higher during the autumn with a rise of about 0.2mg/dL in the mean calcium levels compared to spring and summer (P<0.001). The odds ratio of calcium level above 11.5mg/dL is highest in the autumn (OR=1.275, P=0.018).

CONCLUSION

We show seasonal variation in serum 25-hydroxyvitamin D, PTH, and calcium levels in patients with PHPT. These seasonal variations cause transition to pathological values that may influence diagnosis and treatment of PHPT patients.

Seasonal Variability in Vitamin D Levels No Longer Detectable in Primary Hyperparathyroidism

CONTEXT

Seasonal variability in 25-hydroxyvitamin D [25(OH)D] and PTH levels in the general population has been associated with differences in bone turnover markers, bone density, and fracture risk. Seasonal variability in 25(OH)D and PTH levels has also been reported in primary hyperparathyroidism (PHPT).

OBJECTIVE

Given the widespread use of vitamin D supplements, we sought to determine whether patients with PHPT still demonstrated seasonal variation in 25(OH)D levels.

DESIGN AND SETTING

This cross-sectional study was conducted at a university medical center at a Northeastern U.S. latitude (New York, NY).

PATIENTS

One hundred patients with PHPT participated in the study.

OUTCOME MEASURES

We assessed vitamin D supplement use and seasonal variation in serum 25(OH)D.

RESULTS

Patients had PHPT ([mean ± SD] calcium, 10.8 ± 1.0 mg/dL; PTH, 85 ± 48 pg/mL) with a mean 25(OH)D level of 29 ± 10 ng/mL. Although only one fifth of participants had vitamin D deficiency (19% < 20 ng/mL), more than half were either deficient or insufficient (54% < 30 ng/mL). Sun exposure varied by season, but there were no seasonal differences in levels of 25(OH)D, PTH, bone markers, or bone mineral density, or in the prevalence of 25(OH)D less than 20 or less than 30 ng/mL. Most of the participants (65%) took supplemental vitamin D (dose among users: mean, 1643 ± 1496 IU; median, 1000 IU daily), and supplement users had markedly better vitamin D status than nonusers (25(OH)D < 20 ng/mL: 8 vs 40%; P < .0001; < 30 ng/mL: 40 vs 80%; P = .0001; ≥ 30 ng/mL: 60 vs 20%; P = .0001).

CONCLUSIONS

We found no evidence of seasonal variation in 25(OH)D levels or PHPT disease severity in the Northeastern United States. This change is likely due to widespread high vitamin D supplement intake, which has resulted in better vitamin D status among supplement users and can mask the effect of season on serum 25(OH)D levels.

High prevalence of vitamin D insufficiency in community-dwelling postmenopausal Polish women

Introduction

Inadequate vitamin D level is associated with altered bone turnover and bone loss, which increases the fracture risk.

Aim

To assess the seasonal prevalence of inadequate (insufficient or deficient) serum vitamin D levels in community-dwelling postmenopausal Polish women screened for osteoporosis.

Material and methods

A cross-sectional observational study based on the regional urban non-institutionalized sample (n = 107) of postmenopausal Caucasian women in the age range of 51-83 years, not taking any medication and free from any condition likely to affect vitamin D status or calcium/bone metabolism. The outcome measures were the mean 25-OH vitamin D level across all the seasons and the percentage of vitamin D deficiency and insufficiency and defined as < 20 ng/dl (50 nmol/l) and 20-30 ng/dl (50-75 nmol/l), respectively.

Results

No statistically significant difference has been found in the mean vitamin D level, regardless of the season (p = 0.4). The prevalence of vitamin D deficiency and insufficiency were in spring 54% and 32%, in summer 46% and 46%, in autumn 67% and 27%, and in winter 61% and 22%, respectively.

Conclusions

Vitamin D inadequacy is common in a sample of Polish community-dwelling postmenopausal women regardless of the season.

The direction of shift-work rotation impacts metabolic risk independent of chronotype and social jetlag--an exploratory pilot study

The aim of this pilot study was to explore the risk of metabolic abnormalities in steel workers employed in different shift-work rotations. Male workers in a steel factory [16 employed in a fast clockwise rotation (CW), 18 in slow counterclockwise rotation (CC), 9 day workers (DW); mean age 43.3 ± SD 6.8 years] with at least 5 years experience in their current work schedule participated. All workers provided fasting blood samples between 06:00 and 08:00 h for plasma glucose, insulin, apo-lipoproteins A and B (ApoA, ApoB), high- and low-density lipoproteins (HDL and LDL), total cholesterol (tCH), triglycerides (TG), minimally oxidized (mox) LDL, C-reactive protein (CRP), interleukin-8 (IL-8) and serum 25-hydroxyvitamin D (25(OH)D). HOMA index (homeostatic model assessment) was calculated to evaluate insulin resistance, beta cell function and risk of diabetes. Information on demographics, health, stimulants, sleep, social and work life, chronotype (phase of entrainment) and social jetlag (difference between mid-sleep on workdays and free days) as a surrogate for circadian disruption was collected by questionnaire. Neither chronotype nor social jetlag was associated with any of the metabolic risk blood markers. There were no significant differences in 25(OH)D, ApoA, ApoB, CRP, HDL, IL-8, insulin, LDL, mox-LDL, mox-LDL/ApoB ratio, tCH and TG levels between the three work groups. Although we did observe absolute differences in some of these markers, the small sample size of our study population might prevent these differences being statistically significant. Fasting glucose and HOMA index were significantly lower in CW compared to DW and CC, indicating lower metabolic risk. Reasons for the lower fasting glucose and HOMA index in CW workers remains to be clarified. Future studies of workers in different shift rotations are warranted to understand better the differential effects of shift-work on individual workers and their health indices.

Impact of comorbidity, age, and gender on seasonal variation in hip fracture incidence. A NOREPOS study

Based on a total of 136,140 hip fractures, we found a distinct seasonal variation in hip fracture incidence present in subgroups defined by age, gender, and comorbidity. The seasonal variation was most pronounced in the youngest and the healthiest patients.

PURPOSE

The purpose of this study was to examine the possible seasonal variation in hip fracture incidence in Norway by comorbidity, age, and gender.

METHODS

Data were retrieved from the NOREPOS Hip Fracture Database containing all hip fractures in Norway during the time period 1994-2008. Hip fractures were identified by computerized hospital discharge diagnoses. Charlson comorbidity index was calculated based on additional diagnoses and categorized (0, 1, and ≥2). Summer was defined as June, July, and August and winter as December, January, and February. Incidence rate ratios for hip fracture according to season were calculated by negative binomial models.

RESULTS

In patients aged 50-103 years, 136,140 eligible fractures were identified (72.5 % women). The relative risk of hip fracture in winter versus summer was 1.40 (95 % confidence interval (CI) 1.36-1.45) in men and 1.26 (95 % CI 1.23-1.28) in women. June had the lowest number of fractures in both genders. We found seasonal variation in all subgroups by age and gender, although least pronounced in patients >79 years. There was a significant interaction between season and comorbidity (p = 0.022). When comparing winter to summer, we found relative risks of 1.40 (95 % CI 1.31-1.50) in patients with Charlson index = 0, 1.29 (95 % CI 1.19-1.40) in patients with Charlson index = 1, and 1.18 (95 % CI 1.08-1.28) in patients with Charlson index ≥2.

CONCLUSIONS

There was a distinct seasonal variation in hip fracture incidence, present in all subgroups of gender, age, or comorbidity. This variation should be accounted for when planning health-care services.