The effects of storage time and sampling season on the stability of serum 25-hydroxy vitamin D and androstenedione

Determinants of vitamin D status in pregnant women and neonates

OBJECTIVES

Evidence suggests a beneficial effect of vitamin D on perinatal health; however, low vitamin D status is prevalent in pregnant women and neonates. The objective was to determine factors that are associated with vitamin D status of mothers in early pregnancy and neonates.

METHODS

The study comprised 1,635 pregnant women from Quebec City and Halifax, Canada, 2002-2010. Vitamin D status was based on the concentration of 25-hydroxy-vitamin D [25(OH)D] determined with a chemiluminescence immunoassay in maternal sera collected at a median of 15 weeks' gestation and in neonatal cord sera at delivery. A questionnaire with information on potential determinants was completed midpregnancy.

RESULTS

A total of 44.8% of mothers and 24.4% of neonates had 25(OH)D concentrations <50 nmol/L. Adjusted mean (95% confidence interval) maternal 25(OH)D levels were higher in summer than in winter by 16.1 nmol/L (13.6-18.7), and in those in the highest versus the lowest category of education by 6.1 nmol/L (0.5-11.8), in BMI <25 kg/m2 versus BMI ≥35 kg/m2 by 8.2 nmol/L (4.0-12.3), and in the highest versus the lowest physical activity category by up to 9.5 nmol/L (2.9-16.1). Determinants of neonatal 25(OH)D levels were similar but also included maternal age, dairy intake, supplement use and 25(OH)D level.

CONCLUSION

This study suggests that vitamin D status of pregnant women and/or neonates might be improved through supplementation, adequate dairy intake, a move towards a healthy pre-pregnancy body weight, and participation in physical activity. Controlled studies are needed to determine the effectiveness of interventions aimed at these factors.

Low Prevalence of Vitamin D Insufficiency among Nepalese Infants Despite High Prevalence of Vitamin D Insufficiency among Their Mothers

Background: Describing vitamin D status and its predictors in various populations is important in order to target public health measures. Objectives: To describe the status and predictors of vitamin D status in healthy Nepalese mothers and infants. Methods: 500 randomly selected Nepalese mother and infant pairs were included in a cross-sectional study. Plasma 25(OH)D concentrations were measured by LC-MS/MS and multiple linear regression analyses were used to identify predictors of vitamin D status. Results: Among the infants, the prevalence of vitamin D insufficiency (25(OH)D <50 nmol/L) and deficiency (<30 nmol/L) were 3.6% and 0.6%, respectively, in contrast to 59.8% and 14.0% among their mothers. Infant 25(OH)D concentrations were negatively associated with infant age and positively associated with maternal vitamin D status and body mass index (BMI), explaining 22% of the variability in 25(OH)D concentration. Global solar radiation, maternal age and BMI predicted maternal 25(OH)D concentration, explaining 9.7% of its variability. Conclusion: Age and maternal vitamin D status are the main predictors of vitamin D status in infants in Bhaktapur, Nepal, who have adequate vitamin D status despite poor vitamin D status in their mothers.

Vitamin D-binding protein and 25-hydroxyvitamin D during pregnancy in mothers whose children later developed type 1 diabetes

BACKGROUND

Levels of 25-hydroxyvitamin D (25-OH D) during late pregnancy have been linked to type 1 diabetes risk in the offspring. Vitamin D-binding protein increases in concentration during pregnancy. We aimed to test whether concentrations of vitamin D-binding protein and 25-OH D throughout pregnancy differed between women whose offspring later developed type 1 diabetes (cases) and controls.

METHODS

A nested case-control study was conducted within a cohort of pregnant women from all over Norway in 1992-1994. Offspring registered in The Norwegian Childhood Diabetes Registry, diagnosed with type 1 diabetes before age 15, defined the case women, giving 113 cases in the study. Two hundred twenty controls were randomly selected within the same cohort. One to four serum samples from each participant drawn at different time points during pregnancy were analysed for vitamin D-binding protein and 25-OH D by radioimmunoassay.

RESULTS

Vitamin D-binding protein and 25-OH D significantly increased by gestational week (p < 0.001) and tended to be lower in cases than in controls, -0.27 µmol/L (95% CI -0.57, 0.03) and -5.01 nmol/L (95% CI -8.03, -0.73), respectively. While first and second trimester concentrations of vitamin D-binding protein and 25-OH D alone were not significantly different, lower third trimester concentrations tended to be associated with higher risk of type 1 diabetes in the offspring, albeit at borderline significance after mutual adjustment.

CONCLUSIONS

In this first study of maternal vitamin D-binding protein measured throughout pregnancy and risk of type 1 diabetes in offspring, lower concentration, particularly in the third trimester, tended to be associated with type 1 diabetes. Copyright © 2016 John Wiley & Sons, Ltd.

Maternal Vitamin D Status at Week 30 of Gestation and Offspring Cardio-Metabolic Health at 20 Years: A Prospective Cohort Study over Two Decades

Background/Objectives

Vitamin D deficiency is common among pregnant women and since the fetus relies exclusively on maternal supply, deficiency could potentially interfere with fetal development. Vitamin D blood concentrations during pregnancy have been associated with offspring cardio-metabolic health in a few previous studies but the evidence is still inconsistent and only one previous study has followed the offspring into adulthood. The aim of the present study was to investigate the association between maternal serum concentration of vitamin D (25(OH)D) in week 30 of gestation and offspring cardio-metabolic risk factors at 20 years.

Subjects/Methods

A follow up study of a Danish birth cohort from 1988–89 (n = 965) was conducted. A blood sample was drawn from the women in week 30 of gestation. In 2008–2009, 95% of the original mother and child dyads could be identified in the central registration registry and were alive and living in Denmark. The offspring were followed up with self-reported anthropometrics (N = 629, 69%) and a clinical examination (N = 410, 45%). Multiple linear regression was used to estimate the association between maternal 25(OH)D and offspring cardio-metabolic risk factors adjusting for potential confounders.

Results

No overall association was observed between maternal 25(OH)D in week 30 of gestation and offspring cardio-metabolic risk factors. However, the analyses did suggest a possible inverse association with blood pressure in females.

Conclusions

No clear association between maternal 25(OH)D concentration in week 30 of gestation and cardio-metabolic risk factors in the 20 year old offspring was found.

Association of serum 25-hydroxyvitamin D concentration with HLA-B, -DRB1 and -DQB1 genetic polymorphisms

BACKGROUND/OBJECTIVES

The human leukocyte antigen (HLA) gene region associates with the risk for several autoimmune diseases, including type 1 diabetes. An association between vitamin D deficiency and several autoimmune diseases has been suggested. We tested the association between serum 25-hydroxyvitamin D (25OHD) concentrations and HLA alleles in pregnant Finnish women.

SUBJECTS/METHODS

HLA-B (n=395), HLA-DRB1 (n=501) and HLA-DQB1 (n=475) alleles were genotyped in pregnant women (mothers of children who later developed type 1 diabetes and mothers of non-diabetic children). HLA-B alleles were divided into supertypes that share similar peptide-binding specificity. Serum 25OHD concentration had been previously measured in these women from sera collected during the first trimester of pregnancy. Multiple testing was controlled for using the false discovery rate method.

RESULTS

An association was found between 25OHD concentration and HLA-B44 supertype (P=0.009); women with HLA-B44 supertype (B*18, B*37, B*40 and B*44 alleles) had lower 25OHD concentrations. No association was found between HLA-DRB1 or -DQB1 alleles and 25OHD concentration.

CONCLUSIONS

In this study we found for the first time an association between HLA genetic polymorphisms and 25OHD concentration. In future studies, the mechanistic background of this association and the role of vitamin D in the regulation of HLA gene expression should be investigated.

Serum vitamin D status and bacterial vaginosis prevalence and incidence in Zimbabwean women

BACKGROUND

Bacterial vaginosis, a highly prevalent vaginal condition, is correlated with many adverse reproductive outcomes. In some studies, low vitamin D status (measured as serum 25-hydroxyvitamin D, 25[OH]D) has been associated with increased prevalence of bacterial vaginosis.

OBJECTIVES

We examined the cross-sectional association between vitamin D status and prevalence of bacterial vaginosis, separately for pregnant and nonpregnant women. Using prospectively collected data, we also characterized the effect of time-varying vitamin D status on incident bacterial vaginosis.

STUDY DESIGN

We quantified 25(OH)D in stored sera collected quarterly from 571 Zimbabwean women participating in the Hormonal Contraception and Risk of HIV Acquisition Study. The analysis was restricted to women not using hormonal contraception. We characterized associations between vitamin D insufficiency (defined as 25[OH]D ≤ 30 ng/mL vs > 30 ng/mL) and prevalence of bacterial vaginosis among nonpregnant women at the enrollment visit and among pregnant women at the first follow-up visit that pregnancy was detected. Among women who were negative for bacterial vaginosis at enrollment (n = 380), we also assessed the effect of time-varying vitamin D status on incident bacterial vaginosis. We used the Liaison 25(OH)D total assay to measure 25(OH)D. Bacterial vaginosis was diagnosed via Nugent score.

RESULTS

At enrollment, the prevalence of bacterial vaginosis was 31% and overall median 25(OH)D was 29.80 ng/mL (interquartile range, 24.70-34.30 ng/mL): 29.75 ng/mL (interquartile range, 25.15-33.95 ng/mL) among women with bacterial vaginosis, and 29.90 ng/mL (interquartile range, 24.70-34.50 ng/mL) among women without bacterial vaginosis. Among pregnant women, the prevalence of bacterial vaginosis was 27% and overall median 25(OH)D was 29.90 ng/mL (interquartile range, 24.10-34.00 ng/mL): 30.80 ng/mL (interquartile range, 26.10-36.90 ng/mL) among women with bacterial vaginosis, and 29.10 ng/mL (interquartile range, 23.80-33.45 ng/mL) among women without bacterial vaginosis. Vitamin D levels ≤ 30 ng/mL were not associated with a prevalence of bacterial vaginosis in nonpregnant women (adjusted prevalence ratio, 1.04; 95% confidence interval, 0.81-1.34) or pregnant women (adjusted prevalence ratio, 0.88, 95% confidence interval, 0.51-1.54). Vitamin D levels ≤ 30 ng/mL were similarly not associated with incident bacterial vaginosis (adjusted hazard ratio, 0.98, 95% confidence interval, 0.73-1.31). Our findings were robust to alternative specifications of vitamin D status including using a cut point for vitamin D deficiency of < 20 ng/mL vs ≥ 20 ng/mL and modeling 25(OH)D as a continuous variable.

CONCLUSION

Among reproductive-age Zimbabwean women, insufficient vitamin D was not associated with increased bacterial vaginosis prevalence or incidence. Given established associations between bacterial vaginosis and poor reproductive outcomes, identification of factors leading to high bacterial vaginosis prevalence is urgently needed.

Vitamin D Status and Gestational Diabetes: Effect of Smoking Status during Pregnancy

BACKGROUND

Vitamin D status, as measured by serum 25-hydroxyvitamin D (25(OH)D), has been shown in some studies to be inversely associated with gestational diabetes risk. Recently, it has been suggested that maternal smoking status may modify this relationship. We explored the association between 25(OH)D concentration and gestational diabetes and determined if there was an interaction between smoking and 25(OH)D.

METHODS

A nested case-control study was conducted in Halifax, Nova Scotia and Quebec City, Quebec. Women were recruited before 20 weeks gestation and 25(OH)D was measured. Cases were women who developed gestational diabetes and controls were frequency matched to cases on study site, gestational age at blood draw, and season and year of blood draw. Logistic regression models estimated adjusted odds ratios (aOR) and 95% confidence intervals (CI). Models were tested for multiplicative and additive interaction, which was estimated by relative excess risk due to interaction (RERI).

RESULTS

The study included 395 gestational diabetes cases and 1925 controls. Women who smoked during pregnancy and had 25(OH)D concentrations <30 nmol/L had an aOR = 3.73 [95% CI 1.95, 7.14] compared to non-smokers with 25(OH)D concentrations ≥50 nmol/L. Additive interaction was detected between smoking status and 25(OH)D [RERI = 2.44, 95% CI 0.03, 4.85].

CONCLUSION

Our study supports the inverse association of vitamin D status with gestational diabetes risk, particularly among women who smoke during pregnancy. More research is needed to confirm this finding and, if confirmed, to determine the mechanism by which the combined effect of smoking and low vitamin D status increases the risk of developing gestational diabetes.

Serum 25-hydroxyvitamin D concentrations in Mid-adulthood and Parkinson's disease risk

BACKGROUND

Low vitamin D levels are common among patients with Parkinson's disease (PD). Experimental evidence further suggests that vitamin D may be protective against PD. The objective of this study was to prospectively assess the association between serum 25-hydroxyvitamin D and PD among 12,762 participants of the Atherosclerosis Risk in Communities Study cohort.

METHODS

Serum samples were collected in 1990-1992, and 25-hydroxyvitamin D was measured by liquid chromatography mass spectrometry. A total of 67 incident PD cases were identified through December 31, 2008. The median length of follow-up was 17 years. We used Cox proportional hazards models to obtain hazard ratios and 95% confidence intervals, adjusting for age, sex, and race. We did not find any association between serum 25-hydroxyvitamin D concentrations and PD risk, regardless of how serum 25-hydroxyvitamin D was modeled. Compared with participants with serum 25-hydroxyvitamin D < 20 ng/mL, the hazards ratio for PD was 1.05 (95% confidence interval, 0.58-1.90) for 20-30 ng/mL and 1.14 (95% confidence interval, 0.59- 2.23) for ≥30 ng/mL. Similar results were obtained in sensitivity analyses that included white participants only and that were stratified by the length of follow-up.

CONCLUSION

This prospective study lends no support to the hypothesis that vitamin D may reduce the risk of PD. © 2016 International Parkinson and Movement Disorder Society.

Associations between Vitamin D Status and Type 2 Diabetes Measures among Inuit in Greenland May Be Affected by Other Factors

OBJECTIVE

Epidemiological studies have provided evidence of an association between vitamin D insufficiency and type 2 diabetes. Vitamin D levels have decreased among Inuit in Greenland, and type 2 diabetes is increasing. We hypothesized that the decline in vitamin D could have contributed to the increase in type 2 diabetes, and therefore investigated associations between serum 25(OH)D3 as a measure of vitamin D status and glucose homeostasis and glucose intolerance in an adult Inuit population.

METHODS

2877 Inuit (≥18 years) randomly selected for participation in the Inuit Health in Transition study were included. Fasting- and 2hour plasma glucose and insulin, C-peptide and HbA1c were measured, and associations with serum 25(OH)D3 were analysed using linear and logistic regression. A subsample of 330 individuals who also donated a blood sample in 1987, were furthermore included.

RESULTS

After adjustment, increasing serum 25(OH)D3 (per 10 nmol/L) was associated with higher fasting plasma glucose (0.02 mmol/L, p = 0.004), 2hour plasma glucose (0.05 nmol/L, p = 0.002) and HbA1c (0.39%, p<0.001), and with lower beta-cell function (-1.00 mmol/L, p<0.001). Serum 25(OH)D3 was positively associated with impaired fasting glycaemia (OR: 1.08, p = 0.001), but not with IGT or type 2 diabetes.

CONCLUSIONS

Our results did not support an association between low vitamin D levels and risk of type 2 diabetes. Instead, we found weak positive associations between vitamin D levels and fasting- and 2hour plasma glucose levels, HbA1c and impaired fasting glycaemia, and a negative association with beta-cell function, underlining the need for determination of the causal relationship.

Assessing vitamin D nutritional status: Is capillary blood adequate?

BACKGROUND

Venous blood is the usual sample for measuring various biomarkers, including 25-hydroxyvitamin D (25OHD). However, it can prove challenging in infants and young children. Hence the finger-prick capillary collection is an alternative, being a relatively simple procedure perceived to be less invasive. We elected to validate the use of capillary blood sampling for 25OHD quantification by liquid chromatography tandem-mass spectrometry (LC/MS-MS).

METHODS

Venous and capillary blood samples were simultaneously collected from 15 preschool-aged children with asthma 10days after receiving 100,000IU of vitamin-D3 or placebo and 20 apparently healthy adult volunteers. 25OHD was measured by an in-house LC/MS-MS method.

RESULTS

The venous 25OHD values varied between 23 and 255nmol/l. The venous and capillary blood total 25OHD concentrations highly correlated (r(2)=0.9963). The mean difference (bias) of capillary blood 25OHD compared to venous blood was 2.0 (95% CI: -7.5, 11.5) nmol/l.

CONCLUSION

Our study demonstrates excellent agreement with no evidence of a clinically important bias between venous and capillary serum 25OHD concentrations measured by LC/MS-MS over a wide range of values. Under those conditions, capillary blood is therefore adequate for the measurement of 25OHD.

Biomarkers of Vitamin D Status and Risk of ESRD

BACKGROUND

Disordered mineral metabolism is characteristic of decreased kidney function. However, the prospective associations between circulating levels of vitamin D binding protein, vitamin D, and end-stage renal disease (ESRD) have not been extensively evaluated in epidemiologic studies.

STUDY DESIGN

Nested case-control study.

SETTING & PARTICIPANTS

Middle-aged black and white men and women from 4 US communities.

PREDICTORS

Baseline levels of vitamin D binding protein, 25-hydroxyvitamin D (25[OH]D), and 1,25-dihydroxyvitamin D (1,25[OH]2D) were measured in blood samples collected at study visit 4 (1996-1998) of the ARIC (Atherosclerosis Risk in Communities) Study.

OUTCOME

ESRD cases (n=184) were identified through hospitalization diagnostic codes from 1996 to 2008 and were frequency matched to controls (n=251) on categories of estimated glomerular filtration rate, albuminuria, diabetes mellitus, sex, and race.

MEASUREMENTS

Logistic regression was used to estimate the association between mineral metabolism biomarkers (vitamin D binding protein, 25(OH)D, and 1,25(OH)2D) and incident ESRD, adjusting for age, sex, race, estimated glomerular filtration rate, albuminuria, diabetes mellitus, hypertension, education, specimen type, and serum levels of calcium, phosphate, and parathyroid hormone.

RESULTS

Higher vitamin D binding protein levels were associated with elevated risk for incident ESRD (OR, 1.76; 95% CI, 1.22-2.54; P=0.003). Higher free and bioavailable 25(OH)D levels were associated with reduced risk for incident ESRD (ORs of 0.65 [95% CI, 0.46-0.92; P=0.02] and 0.63 [95% CI, 0.43-0.91; P=0.02] for free and bioavailable 25[OH]D, respectively). There was no association between ESRD and overall levels of 25(OH)D (OR, 0.83; 95% CI, 0.58-1.19; P=0.3) or 1,25(OH)2D (OR, 0.73; 95% CI, 0.48-1.13; P=0.2).

LIMITATIONS

Lack of direct measurement of free and bioavailable vitamin D.

CONCLUSIONS

In the general population, blood levels of vitamin D binding protein were positively associated and blood levels of free and bioavailable 25(OH)D were inversely associated with new-onset ESRD during follow-up.

Relationship of low vitamin D status with positive, negative and cognitive symptom domains in people with first-episode schizophrenia

AIM

Deficient vitamin D levels are very common among Americans of all ages and ethnicities, but little is known about its prevalence or associated problems among those with schizophrenia.

METHODS

Stored plasma from 20 recent onset schizophrenia subjects and 20 matched healthy comparison subjects were analysed for 25 OH vitamin D, and related to measures of symptom severity and neurocognition.

RESULTS

There was no significant difference in mean 25 OH vitamin D between the schizophrenia and the healthy comparison subjects (28.2 standard deviation (SD) 12.6 ng mL(-1) vs. 29.9 SD 14.3 ng mL(-1) ), and about half the subjects in each group had insufficient levels (<30 ng mL(-1) ). Among psychosis subjects, greater severity of negative symptoms was correlated with lower vitamin D status (r = -0.55, P = 0.012); the correlations of overall symptom severity and positive symptom severity with 25 OH vitamin D levels approached significance (r = -0.42, P = 0.07 and r = -0.36, P = 0.12, respectively). There was no relationship of vitamin D with depressive symptoms. Among the schizophrenia subjects, lower 25 OH vitamin D levels were associated with more severe overall cognitive deficits (r = 0.56, P = 0.019).

CONCLUSION

This study found that lower vitamin D levels in schizophrenia subjects were associated with more severe negative symptoms and overall cognitive deficits. However, the cross-sectional design precludes any conclusions about whether low vitamin D status in fact causes more severe negative symptoms and cognitive impairments. No relationship was found between lower vitamin D levels and depressive symptoms.

Vitamin D Status in Different Stages of Disease Severity in Dogs with Chronic Valvular Heart Disease

Background

In humans with heart disease, vitamin D deficiency is associated with disease progression and a poor prognosis. A recent study showed that serum 25‐hydroxyvitamin D [25(OH)D] concentration, the hallmark of vitamin D status, was lower in dogs with heart failure than in normal dogs, and a low concentration was associated with poor outcome in dogs with heart failure.

Objectives

To elucidate the vitamin D status of dogs with chronic valvular heart disease (CVHD) at different stages of disease severity.

Animals

Forty‐three client‐owned dogs with CVHD.

Methods

In this cross‐sectional study, dogs were divided into 3 groups (14 dogs in Stage B1, 17 dogs in Stage B2, and 12 dogs in Stage C/D) according to ACVIM guidelines. Dogs underwent clinical examination including echocardiography. Serum 25(OH)D concentrations were measured in each dog.

Results

Serum 25(OH)D concentration was significantly lower in Stage B2 (median, 33.2 nmol/L; range, 4.9–171.7 nmol/L) and C/D (13.1 nmol/L; 4.9–58.1 nmol/L) than in Stage B1 (52.5 nmol/L; 33.5–178.0 nmol/L) and was not significantly different between Stage B2 and Stage C/D. Among clinical variables, there were significant negative correlations between 25(OH)D concentration and both left atrial‐to‐aortic root ratio and left ventricular end‐diastolic diameter normalized for body weight.

Conclusions and Clinical Importance

These results indicate that vitamin D status is associated with the degree of cardiac remodeling, and the serum 25(OH)D concentration begins to decrease before the onset of heart failure in dogs with CVHD.

Association Between Prediagnostic Serum 25-Hydroxyvitamin D Concentration and Glioma

There are no previous studies of the association between prediagnostic serum vitamin D concentration and glioma. Vitamin D has immunosuppressive properties; as does glioma. It was, therefore, our hypothesis that elevated vitamin D concentration would increase glioma risk. We conducted a nested case-control study using specimens from the Janus Serum Bank cohort in Norway. Blood donors who were subsequently diagnosed with glioma (n = 592), between 1974 and 2007, were matched to donors without glioma (n = 1112) on date and age at blood collection and sex. We measured 25-hydroxyvitamin D [25(OH)D], an indicator of vitamin D availability, using liquid chromatography coupled with mass spectrometry. Seasonally adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated for each control quintile of 25(OH)D using conditional logistic regression. Among men diagnosed with high grade glioma >56, we found a negative trend (P = .04). Men diagnosed ≤ 56 showed a borderline positive trend (P = .08). High levels (>66 nmol/L) of 25(OH)D in men >56 were inversely related to high grade glioma from ≥2 yr before diagnosis (OR = 0.59; 95% CI = 0.38, 0.91) to ≥15 yr before diagnosis (OR = 0.61; 95% CI = 0.38,0.96). Our findings are consistent long before glioma diagnosis and are therefore unlikely to reflect preclinical disease.

Association of Vitamin D Status and Clinical Outcome in Dogs with a Chronic Enteropathy

Background

Dogs with a chronic enteropathy (CE) have a lower vitamin D status, than do healthy dogs. Vitamin D status has been associated with a negative clinical outcome in humans with inflammatory bowel disease.

Objectives

To examine the relationship between serum 25 hydroxyvitamin D (25(OH)D) concentrations at diagnosis and clinical outcome in dogs with a CE.

Animals

Forty‐one dogs diagnosed with CE admitted to the Royal Dick School of Veterinary Studies, Hospital for Small Animals between 2007 and 2013.

Methods

Retrospective review. Serum 25(OH)D concentrations were compared between dogs which were alive at follow up or had died because of non‐CE‐related reasons (survivors) and dogs which died or were euthanized due to their CE (non‐survivors). A binary logistic regression analysis was performed to determine significant predictors of death in dogs with CE.

Results

Serum concentrations of 25(OH)D at the time a CE was diagnosed were significantly lower in nonsurvivors (n = 15) (median nonsurvivors 4.36 ng/mL, interquartile range 1.6–17.0 ng/mL), median survivors (n = 26) (24.9 ng/mL interquartile range 15.63–39.45 ng/mL, P < .001). Serum 25(OH)D concentration was a significant predictor of death in dogs with CE (odds ratio 1.08 [95% CI 1.02–1.18)]).

Conclusions

Serum 25(OH)D concentrations at diagnosis are predictive of outcome in dogs with CE. The role of vitamin D in the initiation and outcome of chronic enteropathies in dogs is deserving of further study.

25-Hydroxyvitamin D Concentration and Sleep Duration and Continuity: Multi-Ethnic Study of Atherosclerosis

STUDY OBJECTIVES

To determine the associations of 25-hydroxyvitamin D (25(OH)D) concentration with sleep continuity, quality, and symptoms, and to explore race/ethnic variation.

DESIGN

Cross-sectional study.

SETTING

Multi-Ethnic Study of Atherosclerosis (MESA).

PARTICIPANTS

There were 1,721 adults.

MEASUREMENTS AND RESULTS

Sleep outcomes were measured by polysomnography, actigraphy, and questionnaires. Serum 25(OH)D concentration was expressed by clinical thresholds (< 20, 20-29, ≥ 30 ng/mL) and continuously. Using linear regression, we determined the associations between 25(OH)D concentration and sleep duration, efficiency, and symptoms, and assessed race/ethnic variation. Mean age was 68.2 ± 9.1 y, and 37.2% were white, 27.7% African American, 11.9% Chinese Americans, and 23.2% Hispanic. Mean 25(OH)D concentration was 25.4 ± 10.5 ng/mL. 25(OH)D deficient participants had the shortest sleep duration, lowest sleep efficiency, and highest sleepiness scores. After adjusting for demographics, obesity, and health habits, deficient individuals slept an average of 13.0 min (95% confidence interval, -22.8, -3.2) shorter than sufficient individuals. Race/ethnic-stratified analyses indicated that the strongest associations were in African Americans, in whom adjusted sleep duration was 25.6 ± 11.7 min shorter in deficient versus sufficient individuals (P = 0.04), and in Chinese Americans, adjusted apnea-hypopnea index (AHI) was 7.5 ± 3.3 events/h higher in deficient versus sufficient individuals.

CONCLUSION

Overall, there were modest associations between 25-hydroxyvitamin D (25(OH)D) concentration and sleep traits. However, race-stratified analyses suggested the association between 25(OH)D concentration and sleep traits varied by race/ethnicity. Vitamin D deficiency was most strongly associated with short sleep duration in African Americans and with elevated apnea-hypopnea index in Chinese Americans, suggesting that race/ethnicity may modify these associations.

Plasma 1,25-Dihydroxyvitamin D and the Risk of Developing Hypertension: The Prevention of Renal and Vascular End-Stage Disease Study

Previous observational studies on the vascular effects of vitamin D have predominantly relied on measurement of its inactive precursor, 25-hydroxyvitamin D, whereas the active metabolite 1,25-dihydroxyvitamin D may be of more physiological relevance. We prospectively studied the associations of 1,25-dihydroxyvitamin D and 25-hydroxyvitamin D with hypertension risk (blood pressure ≥140/90 mm Hg or initiation of blood pressure-lowering drugs) in 5066 participants aged 28 to 75 years, free of hypertension at baseline from the Prevention of Renal and Vascular End-Stage Disease Study, a well-defined cohort with serial follow-up. We measured plasma 1,25-dihydroxyvitamin D and 25-hydroxyvitamin D using liquid chromatography-tandem mass spectrometry. Mean±SD plasma concentration of 1,25-dihydroxyvitamin D was 145±47.0 pmol/L and 25-hydroxyvitamin D was 58.6±23.8 nmol/L. During a median follow-up of 6.4 years, 1036 participants (20.5%) developed hypertension. As expected, low 25-hydroxyvitamin D was associated with a higher hypertension risk; each 1-SD decrement in 25-hydroxyvitamin D was associated with a 8% higher hypertension risk (hazard ratio, 1.08; 95% confidence interval, 1.01-1.16) after adjustment for potential confounders. However, the association of 1,25-dihydroxyvitamin D was in the opposite direction; each 1-SD decrement of 1,25-dihydroxyvitamin D was associated with a 10% lower hypertension risk (hazard ratio, 0.90; 95% confidence interval, 0.84-0.96), independent of potential confounders. In contrast to the inverse association between 25-hydroxyvitamin D and hypertension risk, 1,25-dihydroxyvitamin D was positively associated with risk of hypertension. Thus, higher circulating concentrations of 1,25-dihydroxyvitamin D are associated with a higher risk of hypertension.

Effect of adipose tissue volume loss on circulating 25-hydroxyvitamin D levels: results from a 1-year lifestyle intervention in viscerally obese men

BACKGROUND/OBJECTIVES

Although weight loss has been associated with changes in circulating 25-hydroxyvitamin D (25(OH)D) levels, the quantification of the increase in 25(OH)D levels as a function of adipose tissue volume loss precisely assessed by imaging has not been reported before. The objective of this substudy was to describe the effects of a 1-year lifestyle intervention on plasma 25(OH)D levels. The relationships between changes in 25(OH)D levels and changes in adiposity volume (total and by adipose tissue compartment) were studied.

SUBJECTS/METHODS

This intervention study was performed between 2004 and 2006 and participants were recruited from the general community. Sedentary, abdominally obese and dyslipidemic men (n=103) were involved in a 1-year lifestyle modification program. Subjects were individually counseled by a kinesiologist and a nutritionist once every 2 weeks during the first 4 months with subsequent monthly visits in order to elicit a 500-kcal daily energy deficit and to increase physical activity/exercise habits. Body weight, body composition and fat distribution were assessed by dual-energy X-ray absorptiometry and computed tomography, whereas the 25(OH)D levels were measured with an automated assay.

RESULTS

The 1-year intervention resulted in a 26% increase in circulating 25(OH)D (from 48±2 nmol l(-1) or 19±0.8 ng ml(-1) (±s.e.m.) to 58±2 nmol l(-1) or 23±0.8 ng ml(-1), P<0.0001) along with a 26% decrease in visceral adiposity volume (from 1947±458 to 1459±532 cm3). One-year increases in 25(OH)D levels correlated inversely with changes in all adiposity indices, especially Δvisceral (r=-0.36, P<0.0005) and Δtotal abdominal (r=-0.37, P<0.0005) adipose tissue volumes.

CONCLUSIONS

These results indicate that there is a linear increase in circulating 25(OH)D levels as a function of adiposity volume loss, and therefore suggest a role of adiposity reduction in the management of obesity-associated vitamin D insufficiency.

Vitamin d in the general population of young adults with autism in the faroe islands

Vitamin D deficiency has been proposed as a possible risk factor for developing autism spectrum disorder (ASD). 25-Hydroxyvitamin D₃ (25(OH)D₃) levels were examined in a cross-sectional population-based study in the Faroe Islands. The case group consisting of a total population cohort of 40 individuals with ASD (aged 15–24 years) had significantly lower 25(OH)D₃ than their 62 typically-developing siblings and their 77 parents, and also significantly lower than 40 healthy age and gender matched comparisons. There was a trend for males having lower 25(OH)D₃ than females. Effects of age, month/season of birth, IQ, various subcategories of ASD and Autism Diagnostic Observation Schedule score were also investigated, however, no association was found. The very low 25(OH)D₃ in the ASD group suggests some underlying pathogenic mechanism.

Hydroxylated polychlorinated biphenyls decrease circulating steroids in female polar bears (Ursus maritimus)

As a top predator in the Arctic food chain, polar bears (Ursus maritimus) are exposed to high levels of persistent organic pollutants (POPs). Because several of these compounds have been reported to alter endocrine pathways, such as the steroidogenesis, potential disruption of the sex steroid synthesis by POPs may cause implications for reproduction by interfering with ovulation, implantation and fertility. Blood samples were collected from 15 female polar bears in Svalbard (Norway) in April 2008. The concentrations of nine circulating steroid hormones; dehydroepiandrosterone (DHEA), androstenedione (AN), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2), 17β-estradiol (βE2), pregnenolone (PRE) and progesterone (PRO) were determined. The aim of the study was to investigate associations among circulating levels of specific POP compounds and POP-metabolites (hydroxylated PCBs [OH-PCBs] and hydroxylated PBDEs [OH-PBDEs]), steroid hormones, biological and capture variables in female polar bears. Inverse correlations were found between circulating levels of PRE and AN, and circulating levels of OH-PCBs. There were no significant relationships between the steroid concentrations and other analyzed POPs or the variables capture date and capture location (latitude and longitude), lipid content, condition and body mass. Although statistical associations do not necessarily represent direct cause-effect relationships, the present study indicate that OH-PCBs may affect the circulating levels of AN and PRE in female polar bears and that OH-PCBs thus may interfere with the steroid homeostasis. Increase in PRO and a decrease in AN concentrations suggest that the enzyme CYP17 may be a potential target for OH-PCBs. In combination with natural stressors, ongoing climate change and contaminant exposure, it is possible that OH-PCBs may disturb the reproductive potential of polar bears.

Independent association of severe vitamin D deficiency as a risk of acute myocardial infarction in Indians

BACKGROUND

Association of vitamin D deficiency with coronary heart disease (CHD) has been widely reported. Emerging data has shown high prevalence of vitamin D deficiency among Indians. However, this association has not been studied in Indians.

METHODS

A case-control study with 120 consecutive cases of first incident acute myocardial infarction (MI) and 120 age and gender matched healthy controls was conducted at All India Institute of Medical Sciences, New Delhi. The standard clinical and biochemical risk factors for MI were assessed for both cases and controls. Serum 25 (OH) vitamin D assay was performed from stored samples for cases and controls using radioimmunoassay.

RESULTS

Vitamin D deficiency [25(OH) D < 30 ng/ml] was highly prevalent in cases and controls (98.3% and 95.8% respectively) with median levels lower in cases (6 ng/ml and 11.1 ng/ml respectively; p < 0.001). The cases were more likely to have diabetes, hypertension and consume tobacco and alcohol. They had higher waist hip ratio, total and LDL cholesterol. Multivariate logistic regression analysis revealed severe vitamin D deficiency [25(OH) vitamin D < 10 ng/ml] was associated with a risk of MI with an odds ratio of 4.5 (95% CI 2.2-9.2).

CONCLUSIONS

This study reveals high prevalence of vitamin D deficiency among cases of acute MI and controls from India, with levels of 25 (OH)D being significantly lower among cases. Despite rampant hypovitaminosis, severe vitamin D deficiency was associated with acute MI after adjusting for conventional risk factors. This association needs to be tested in larger studies in different regions of the country.

Decrease in vitamin D status in the Greenlandic adult population from 1987-2010

Background

Low vitamin D status may be pronounced in Arctic populations due to limited sun exposure and decreasing intake of traditional food.

Objective

To investigate serum 25(OH)D3 as a measure of vitamin D status among adult Inuit in Greenland, predictors of low serum 25(OH)D3 concentrations and the trend from 1987 to 2005–2010.

Design

A total of 2877 randomly selected Inuit (≥18 years) from the Inuit Health in Transition study were included. A sub-sample (n = 330) donated a blood sample in 1987 which allowed assessment of time trends in vitamin D status.

Results

The geometric mean serum 25(OH)D3 (25[OH]D2 concentrations were negligible and not reported) in 2005–2010 was lowest among the 18–29 year old individuals (30.7 nmol/L; 95% CI: 29.7; 31.7) and increased with age. In all age-groups it decreased from 1987 to 2005–2010 (32%–58%). Low 25(OH)D3 concentrations (<50 nmol/L) were present in 77% of the 18–29 year old and decreased with age. A characteristic seasonal variation in 25(OH)D3 concentrations was observed (range 33.2–57.1 nmol/L, p<0.001), with the highest concentrations in August to October. Age (2.0% per year increase; CI: 1.7, 2.2), female gender (7.1%; CI: 2.0; 12.5), alcohol intake (0.2% per increase in drinks/week; 0.0; 0.4), and traditional diet (10.0% per 100 g/d increase; CI: 7.9; 12.1) were associated with increased serum 25(OH)D3, whereas smoking (−11.6%; CI: −16.2; −6.9), BMI (−0.6%; CI: −1.1; −0.2) and latitude (−0.7% per degree increase; CI: −1.3; −0.2) were associated with decreased concentrations.

Conclusion

We identified a remarkable decrease in vitamin D status from 1987 to 2005–2010 and a presently low vitamin D status among Inuit in Greenland. A change away from a traditional diet may well explain the observed decline. The study argues for the need of increased dietary intake of vitamin D and supplementation might be considered.

Vitamin D levels are low in adult patients with sickle cell disease in Jamaica and West Africa

Background

Patients with sickle cell disease in the USA have been noted to have lower levels of vitamin D – measured as 25-hydroxyvitamin D (25(OH)D) – compared to controls. Average serum 25(OH)D levels are also substantially lower in African Americans than whites, while population distributions of 25(OH)D among Jamaicans of African descent and West Africans are the same as among USA whites. The purpose of this study was to examine whether adult patients with sickle cell disease living in tropical regions had reduced 25(OH)D relative to the general population.

Methods

We analyzed serum 25(OH)D in stored samples collected from studies in Jamaica and West Africa of adult patients with sickle cell disease and adult population controls.

Results

In samples of 20 Jamaicans and 50 West Africans with sickle cell disease mean values of 25(OH)D were 37% and 39% lower than controls, respectively. Metabolic abnormalities in the absorption and conversion pathways are possible causes for the consistent relative deficiency of 25(OH)D in sickle cell disease.

Conclusions

Low 25(OH)D levels in tropical Africa where the burden of sickle cell disease is highest, deserve further investigation, and a randomized trial is warranted to address efficacy of supplementation.

Evidence for threshold effects of 25-hydroxyvitamin D on glucose tolerance and insulin resistance in black and white obese postmenopausal women

We identified normal vs. abnormal 25-hydroxyvitamin D [25(OH)D] concentrations by examining the relation of 25(OH)D to non-bone-related measures (plasma glucose, insulin resistance, lipids, blood pressure, fitness, obesity, and regional adiposity) and asking whether there is a 25(OH)D concentration above and below which the relation between 25(OH)D and outcome changes. We examined the relation between 25(OH)D and outcome by race to see whether race-specific normal ranges are needed, and we examined the role of insulin-like growth factor-1 (IGF-1) in modulating the relation between 25(OH)D and outcome. In a cross-sectional study of 239 overweight and obese, sedentary postmenopausal women without diabetes (83 black, 156 white), outcome measures included plasma lipids, glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), IGF-1, parathyroid hormone (PTH), aerobic fitness, body composition, subcutaneous abdominal and visceral fat, and blood pressure. We identified threshold effects in the association between 25(OH)D and these variables using piecewise linear regressions. We found that 25(OH)D was inversely related to fasting glucose, fasting and 2-h insulin, HOMA-IR, visceral abdominal fat, percentage fat, PTH, and triglycerides. Evidence for a threshold effect of 25(OH)D was found for 2-h glucose, 2-h insulin, fasting insulin, and HOMA-IR. There was no evidence suggesting the need for race-specific normal 25(OH)D concentrations. IGF-1 modulated the relation between 25(OH)D and outcome but only below, and not above, a threshold 25(OH)D concentration. Our findings suggest a threshold effect of 25(OH)D on glucose-insulin metabolism such that 25(OH)D ≥ ∼26 μg/L (65.0 pmol/L) supports normal glucose homeostasis and that the same cut point defining normal 25(OH)D concentration can be used in black and white women. This study was registered at clinicaltrials.gov as NCT01798030.

Cats with inflammatory bowel disease and intestinal small cell lymphoma have low serum concentrations of 25-hydroxyvitamin D

Background

Inflammatory bowel disease (IBD) and intestinal small cell lymphoma (ISCL) are common diseases in cats. The prevalence of alterations in the serum concentrations of fat soluble vitamins, such as vitamin D, in cats with IBD and ISCL is unknown.

Hypothesis/Objectives

The objective of this study was to measure serum 25 hydroxyvitamin D (25[OH]D) concentrations in cats with IBD or ISCL. Serum 25(OH)D also was measured in healthy cats, and in hospitalized ill cats with nongastrointestinal diseases.

Animals

Eighty‐four cats were included in the study: 23 in the healthy group, 41 in the hospitalized ill group, and 20 in the IBD/ISCL group.

Methods

Retrospective study. Serum samples for vitamin D analysis were frozen at −20°C until serum 25(OH)D was measured by high‐performance liquid chromatography (HPLC).

Results

Although there was overlap in serum 25(OH)D concentrations among the 3 groups, serum 25(OH)D concentrations were significantly lower in the cats with IBD or ISCL compared to healthy cats (P < .0001) and hospitalized ill cats (P = .014). In the IBD/ISCL group, there was a significant moderate positive correlation between serum albumin and 25(OH)D concentrations (r = 0.58, P = .018).

Conclusion and Clinical Importance

The median serum concentration of 25(OH)D was significantly lower in cats with IBD/ISCL than in healthy cats and in hospitalized ill cats. Additional studies are required to elucidate the mechanism of hypovitaminosis D in cats with gastrointestinal diseases, to define the best management strategy to treat this complication, and to investigate its potential prognostic implications.

Vitamin D status during pregnancy and the risk of subsequent postpartum depression: a case-control study

Epidemiological studies have provided evidence of an association between vitamin D insufficiency and depression and other mood disorders, and a role for vitamin D in various brain functions has been suggested. We hypothesized that low vitamin D status during pregnancy might increase the risk of postpartum depression (PPD). The objective of the study was thus to determine whether low vitamin D status during pregnancy was associated with postpartum depression. In a case-control study nested in the Danish National Birth Cohort, we measured late pregnancy serum concentrations of 25[OH]D3 in 605 women with PPD and 875 controls. Odds ratios [OR) for PPD were calculated for six levels of 25[OH]D3. Overall, we found no association between vitamin D concentrations and risk of PPD (p = 0.08). Compared with women with vitamin D concentrations between 50 and 79 nmol/L, the adjusted odds ratios for PPD were 1.35 (95% CI: 0.64; 2.85), 0.83 (CI: 0.50; 1.39) and 1.13 (CI: 0.84; 1.51) among women with vitamin D concentrations < 15 nmol/L, 15–24 nmol/L and 25–49 nmol/L, respectively, and 1.53 (CI: 1.04; 2.26) and 1.89 (CI: 1.06; 3.37) among women with vitamin D concentrations of 80–99 nmol/L and ≥ 100 nmol/L, respectively. In an additional analysis among women with sufficient vitamin D (≥ 50 nmol/L), we observed a significant positive association between vitamin D concentrations and PPD. Our results did not support an association between low maternal vitamin D concentrations during pregnancy and risk of PPD. Instead, an increased risk of PPD was found among women with the highest vitamin D concentrations.

Mineral metabolism in growing cats: changes in the values of blood parameters with age

The purpose of this study was to describe changes in calcium, phosphorus, magnesium, parathyroid hormone, calcitriol and calcidiol in cats from 3 to 15 months of age. Fourteen European shorthair healthy cats of both sexes (seven males, seven females) belonging to a research colony were studied from 3 to 15 months of age. Plasma concentrations of total calcium, ionised calcium, albumin, phosphorus, magnesium, intact parathyroid hormone (I-PTH), whole parathyroid hormone (W-PTH), calcidiol and calcitriol were measured at 3, 6, 9, 12 and 15 months of age. From 3 months of age to adulthood cats showed a decrease in calcium (both total and ionised), phosphorus and magnesium. No major changes in PTH were evident, although the ratio of W-PTH:I-PTH decreased significantly with age. A reciprocal change in vitamin D metabolites (decrease in calcitriol and increase in calcidiol) was identified during the growing process. Our results, showing changes in most parameters of mineral metabolism during growth, reinforce the need to use adequate age-related reference values for diagnostic purposes.

The association between plasma 25-hydroxyvitamin D and subgroups in age-related macular degeneration: a cross-sectional study

OBJECTIVES

To evaluate potential differences in plasma 25-hydroxyvitamin in subtypes of age-related macular degeneration (AMD), and in patients in Clinical Age-Related Maculopathy Staging (CARMS) group 5 with or without subretinal fibrosis.

METHODS

This single-center cross-sectional study included 178 participants during a period of 20 months. Ninety-five patients belonged to CARMS 5; twelve belonged to CARMS 4; twenty-two belonged to CARMS 2 or 3; and 49 individuals did not have AMD (CARMS 1). Following a structured interview, a detailed bilateral retinal examination was performed and participants were allocated to their respective subgroups in accordance with the Clinical Age-Related Maculopathy Staging system. Plasma 25-hydroxyvitamin D2 and D3 were analyzed using liquid chromatography-tandem mass spectrometry. Genomic DNA was extracted from leukocytes and genotyped for single nucleotide polymorphisms (SNPs) in the vitamin D metabolism. Differences in plasma 25-hydroxyvitamin D were determined in the subgroups as well as between patients in CARMS 5 with or without subretinal fibrosis.

RESULTS

Plasma 25-hydroxyvitamin D was comparable in patients across CARMS groups 1 to 5 (p = 0.83). In CARMS 5, the presence of subretinal fibrosis was associated with significantly lower concentrations of 25-hydroxyvitamin D as compared to the absence of subretinal fibrosis (47.2 versus 75.6 nmol/L, p<0.001). Patients in CARMS 5 with subretinal fibrosis were more likely to have insufficient levels of 25-hydroxyvitamin D compared to patients without subretinal fibrosis (p = 0.006). No association was found between the SNPs rs10877012, rs2228570, rs4588, or rs7041 and AMD subgroups or plasma 25-hydroxyvitamin levels.

CONCLUSIONS

This study suggests that the presence of subretinal fibrosis in patients belonging to CARMS 5 may be associated with a poor vitamin D status. Our observations warrant further investigation into the role of vitamin D in the development of subretinal fibrosis.

Racial differences in the association of serum 25-hydroxyvitamin D concentration with coronary heart disease events

IMPORTANCE

Low circulating concentrations of 25-hydroxyvitamin D (25[OH]D) have been consistently associated with an increased risk of coronary heart disease (CHD) in white populations. This association has not been rigorously evaluated in other races or ethnicities, in which the distributions of 25(OH)D concentration and possibly other aspects of 25(OH)D metabolism differ.

OBJECTIVE

To examine the association of serum 25(OH)D concentration with risk of CHD in a multiethnic population.

DESIGN, SETTING, AND PARTICIPANTS

We studied 6436 participants in the Multi-Ethnic Study of Atherosclerosis (MESA), recruited from July 2000 through September 2002, who were free of known cardiovascular disease at baseline. We measured baseline serum 25(OH)D concentrations using a mass spectrometry assay calibrated to established standards. We tested associations of 25(OH)D with adjudicated CHD events assessed through May 2012.

MAIN OUTCOME AND MEASURES

Primary outcome measure was time to first adjudicated CHD event, defined as myocardial infarction, angina, cardiac arrest, or CHD death.

RESULTS

During a median follow-up of 8.5 years, 361 participants had an incident CHD event (7.38 events per 1000 person-years). Associations of 25(OH)D with CHD differed by race/ethnicity (P for interaction < .05). After adjustment, lower 25(OH)D concentration was associated with a greater risk of incident CHD among participants who were white (n = 167 events; hazard ratio [HR], 1.26 [95% CI, 1.06-1.49] for each 10-ng/mL decrement in 25(OH)D) or Chinese (HR, 1.67 [95% CI, 1.07-2.61]; n = 27). In contrast, 25(OH)D was not associated with risk of CHD in participants who were black (HR, 0.93 [95% CI, 0.73-1.20]; n = 94) or Hispanic (HR, 1.01 [95% CI, 0.77-1.33]; n = 73).

CONCLUSIONS AND RELEVANCE

Lower serum 25(OH)D concentration was associated with an increased risk of incident CHD events among participants who were white or Chinese but not black or Hispanic. Results evaluating 25(OH)D in ethnically homogeneous populations may not be broadly generalizable to other racial or ethnic groups.

Vitamin D levels and risk of multiple sclerosis in patients with clinically isolated syndromes

Background:

Growing evidence suggests that vitamin D deficiency may be one of the most important environmental factors for the development of multiple sclerosis (MS).

Objectives:

The objectives of this paper are to evaluate serum 25-hydroxyvitamin D (25(OH)D) levels in patients with clinically isolated syndromes (CIS) and to examine whether they are related to MS risk.

Methods:

This is a retrospective study of 100 CIS patients hospitalized from 2000 to 2009 at San Raffaele Hospital, Milan, Italy. We evaluated baseline 25(OH)D level as well as clinical, brain magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) data.

Results:

A total of 52% of CIS patients had vitamin D deficiency (25(OH)D < 50 nmol/l). During follow-up (median: 7.17 years), 55 patients developed clinically definite MS (CDMS). Patients with very low (< 10th percentile) and low (< 25th percentile) 25(OH)D levels were particularly at risk of CDMS (HRs (95% CIs): 2.12 (0.91–4.96) and 1.61 (0.85–3.03), respectively), while no further reduction in the HRs of disease was observed at high levels of 25(OH)D. This association was even stronger after adjustment for additional risk factors for CDMS development (HRs (95% CIs) for 25(OH)D levels < 10th and 25th percentiles: 3.34 (1.32–8.45) and 2.04 (0.96–4.36), respectively).

Conclusion:

Low serum vitamin D is associated with increased MS risk in patients with CIS.

Serum 1,25-dihydroxyvitamin D: an outcome prognosticator in human sepsis

In sepsis, the vitamin D active metabolite 1,25-dihydroxyvitamin D (1,25(OH)₂D) may play a crucial role by its action to produce cathelicidin and improve endothelial barrier function, such that a deficiency in 1,25(OH)₂D is associated with poor outcome. To test our hypothesis, we performed analysis of stored plasma samples from a prospective observational study in 91 patients with sepsis, age of 59.1+/−2.0 years, 52.7% females, and 11.0% deaths at 30 days. Vitamin D status, including 25-hydroxyvitamin D (25(OH)D), 1,25(OH)₂D, 24,25-dihydroxyvitamin D (24,25(OH)₂D), and parathyroid hormone (PTH), were measured daily over 3 days after hospital admission. At baseline, 1,25(OH)₂D was significantly different between survivors vs. non-survivors. But there was no significant difference in 25(OH)D, 24,25(OH)₂D, and PTH. In a multivariable binomial logistic regression model, age, total calcium and 1,25(OH)₂D were significant predictors of 30-day mortality. Kaplan Meier analysis showed that patients with mean 1,25(OH)₂D measured over 3 days of < = 13.6 pg/mL had 57.1% 30-day survival compared to 91.7% in patients with 1,25 (OH)₂D level >13.6 pg/mL (p<0.01). From repeated measures regression analysis, there was significant increase in 1,25(OH)₂D for increases in 25(OH)D in both survivors and non-survivors. However, compared to survivors, the low 25(OH)D in non-survivors was insufficient to account for the larger decrease in 1,25(OH)₂D, indicating a dysfunctional 1α-hydroxylase. Additionally, there was a significant negative correlation between PTH and 1,25(OH)₂D in both survivors and non-survivors, suggesting a severe impairment in the effect of PTH to increase renal 1α-hydroxylase activity. In conclusion, low 1,25(OH)₂D levels are associated with increased 30-day mortality in sepsis patients, likely due to impaired 25(OH)D hydroxylation and PTH insensitivity. Our data also suggest that the active metabolite 1,25(OH)₂D may be an important therapeutic target in the design of sepsis clinical trials.

Strong associations of 25-hydroxyvitamin D concentrations with all-cause, cardiovascular, cancer, and respiratory disease mortality in a large cohort study

BACKGROUND

Serum 25-hydroxyvitamin D [25(OH)D] concentration has been linked to mortality in several studies, but appropriate cutoffs to define risk categories are under debate.

OBJECTIVE

We aimed to conduct a repeated-measurements analysis on the association of serum 25(OH)D concentrations with all-cause and cause-specific mortality, with particular attention given to the shape of dose-response relations.

DESIGN

Concentrations of 25(OH)D were measured in n = 9578 baseline and n = 5469 5-y follow-up participants of the ESTHER study, which is a German population-based cohort aged 50-74 y at baseline. Deaths were recorded during 9.5 y of follow-up (median). Restricted cubic splines were used to assess dose-response relations, and Cox regression with time-dependent variables was used to estimate hazard ratios.

RESULTS

During follow-up, 1083 study participants died; of those, 350 individuals died of cardiovascular diseases, 433 individuals died of cancer, and 55 individuals died of respiratory diseases. The overall mortality [HR (95% CI)] of subjects with vitamin D deficiency [25(OH)D concentrations <30 nmol/L] or vitamin D insufficiency [25(OH)D concentrations from 30 to 50 nmol/L) was significantly increased [1.71 (1.43, 2.03) and 1.17 (1.02, 1.35), respectively] compared with that of subjects with sufficient 25(OH)D concentrations (>50 nmol/L)]. Vitamin D deficiency was also associated with increased cardiovascular mortality [1.39 (95% CI: 1.02, 1.89)], cancer mortality [1.42 (95% CI: 1.08, 1.88)] and respiratory disease mortality [2.50 (95% CI: 1.12, 5.56)]. The association of 25(OH)D concentrations with all-cause mortality proved to be a nonlinear inverse association with risk that started to increase at 25(OH)D concentrations <75 nmol/L.

CONCLUSIONS

In this large cohort study, serum 25(OH)D concentrations were inversely associated with all-cause and cause-specific mortality. In particular, vitamin D deficiency [25(OH)D concentration <30 nmol/L] was strongly associated with mortality from all causes, cardiovascular diseases, cancer, and respiratory diseases.

Variability and reproducibility of circulating vitamin D in a nationwide U.S. population

CONTEXT

Most studies examining associations between circulating vitamin D and disease are based on a single measure of vitamin D, which may not reflect levels over time, particularly because vitamin D concentrations vary by season. Few studies evaluated how well multiple 25-hydroxyvitamin D [25(OH)D] measures track within the same individual over time.

OBJECTIVE

This study examined variability and reproducibility of vitamin D by evaluating repeat measurements of plasma 25(OH)D concentrations while accounting for determinants of circulating concentrations including dietary supplement use and latitude of residence from a population of U.S. radiologic technologists.

DESIGN AND PARTICIPANTS

We analyzed circulating 25(OH)D in blood samples taken from 538 men and women from a prospective, nationwide study at two time points within a 1-yr period, most measured in different seasons. Inter- and intra-individual variability, reliability coefficients, and measurement error were examined.

RESULTS

The spearman rank correlation between two measurements of 25(OH)D concentrations was moderate (r = 0.75, P < 0.001) and did not vary significantly by participant characteristics including age, race, or latitude. The intraclass correlation coefficient was 0.72 (95% confidence interval = 0.68-0.76). The deattenuation factor of plasma 25(OH)D levels was 1.39, suggesting that a single measure of vitamin D on a continuous scale in regression analyses may result in attenuated relationships of about 40%.

CONCLUSION

Our results suggest that a single blood sample obtained in spring or fall provides a reasonable average for 25(OH)D over a 1-yr period, but additional studies are needed to estimate variability and agreement in plasma 25(OH)D measurements over longer intervals and younger populations.

Circulating vitamin D metabolites and kidney disease in type 1 diabetes

CONTEXT

Impaired vitamin D metabolism may contribute to the development and progression of diabetic kidney disease.

OBJECTIVE

The aim of the study was to test associations of circulating vitamin D metabolites with risks of incident microalbuminuria, impaired glomerular filtration rate (GFR), and hypertension in type 1 diabetes.

DESIGN

We performed a cohort study of 1193 participants in the Diabetes Control and Complications Trial (DCCT), a randomized clinical trial of intensive diabetes therapy, and its observational follow-up, the Epidemiology of Diabetes Interventions and Complications (EDIC) Study. We measured plasma concentrations of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D, and 24,25-dihydroxyvitamin D by mass spectrometry at the end of the DCCT and tested associations with incident microalbuminuria, impaired GFR, and hypertension over up to 16 yr of EDIC follow-up.

RESULTS

At the time metabolites were measured, mean age was 32.4 yr; mean duration of diabetes, 7.5 yr; mean iothalamate GFR, 132.9 ml/min/1.73 m(2); and geometric mean albumin excretion rate, 11.8 mg/24 h. Over follow-up, 166 cases of microalbuminuria, 54 cases of impaired GFR, and 541 cases of hypertension were observed. Compared with 25(OH)D of at least 30 ng/ml, 25(OH)D below 20 ng/ml was associated with a 65% higher risk of microalbuminuria (95% confidence interval, 7 to 154%) in adjusted analyses. Low concentrations of 24,25-dihydroxyvitamin D, but not 1,25-dihydroxyvitamin D, were also associated with increased risk of microalbuminuria. No circulating vitamin D metabolite was associated with risk of impaired GFR or hypertension.

CONCLUSIONS

Low plasma concentrations of 25(OH)D and 24,25-dihydroxyvitamin D are associated with increased risk of microalbuminuria in type 1 diabetes. In contrast, we did not find evidence linking impaired vitamin D metabolism to early GFR loss or the development of hypertension.

Public health implications of standardized 25-hydroxyvitamin D levels: a decrease in the prevalence of vitamin D deficiency among older women in Germany

OBJECTIVE

To compare the public health implications of using unstandardized immunoassay measurements of serum 25-hydroxyvitamin D [25(OH)D] concentrations versus using measurements standardized by liquid chromatography tandem-mass spectrometry (LC-MS/MS) when assessing the prevalence of 25(OH)D insufficiency and deficiency in various subgroups of individuals.

METHOD

We standardized immunoassay-based measurements of 25(OH)D with LC-MS/MS in a population-based sample of 5386 women aged 50-74 recruited in 2000-2002 in Germany. We used multivariate regression to assess 25(OH)D determinants and the association of vitamin D deficiency with health status.

RESULTS

Prevalences of 25(OH)D levels <50 nmol/L (insufficiency) and <30 nmol/L (deficiency) decreased considerably by standardization. The decrease in vitamin D deficiency (from 64.4% to 17.9%) was particularly strong in March-May among women aged ≥ 65. Independent of season of blood draw and standardization, women ≥ 70 years, obese, or currently smoking had an increased risk of having 25(OH)D levels <30 nmol/L.

CONCLUSION

The proportion of older women with vitamin D deficiency in Germany is much lower than previously reported, but prevalence of vitamin D insufficiency is high. Standardization of 25(OH)D values by immunoassay methods to LC-MS/MS equivalent values or direct measurement by LC-MS/MS is indispensable in drawing valid conclusions about the health implications of vitamin D deficiency or insufficiency.

Genome-wide association analysis of circulating vitamin D levels in children with asthma

Vitamin D deficiency is becoming more apparent in many populations. Genetic factors may play a role in the maintenance of vitamin D levels. The objective of this study was to perform a genome-wide analysis (GWAS) of vitamin D levels, including replication of prior GWAS results. We measured 25-hydroxyvitamin D (25(OH)D) levels in serum collected at the time of enrollment and at year 4 in 572 Caucasian children with asthma, who were part of a multi-center clinical trial, the Childhood Asthma Management Program. Replication was performed in a second cohort of 592 asthmatics from Costa Rica and a third cohort of 516 Puerto Rican asthmatics. In addition, we attempted replication of three SNPs that were previously identified in a large GWAS of Caucasian individuals. The setting included data from a clinical trial of childhood asthmatics and two cohorts of asthmatics recruited for genetic studies of asthma. The main outcome measure was circulating 25(OH)D levels. The 25(OH)D levels at the two time-points were only modestly correlated with each other (intraclass correlation coefficient = 0.33) in the CAMP population. We identified SNPs that were nominally associated with 25(OH)D levels at two time-points in CAMP, and replicated four SNPs in the Costa Rican cohort: rs11002969, rs163221, rs1678849, and rs4864976. However, these SNPs were not significantly associated with 25(OH)D levels in a third population of Puerto Rican asthmatics. We were able to replicate the SNP with the strongest effect, previously reported in a large GWAS: rs2282679 (GC), and we were able to replicate another SNP, rs10741657 (CYP2R1), to a lesser degree. We were able to replicate two of three prior significant findings in a GWAS of 25(OH)D levels. Other SNPs may be additionally associated with 25(OH)D levels in certain populations.

Serum 25-hydroxyvitamin D concentration and risk for major clinical disease events in a community-based population of older adults: a cohort study

BACKGROUND

Circulating concentrations of 25-hydroxyvitamin D [25-(OH)D] are used to define vitamin D deficiency. Current clinical 25-(OH)D targets based on associations with intermediate markers of bone metabolism may not reflect optimal levels for other chronic diseases and do not account for known seasonal variation in 25-(OH)D concentration.

OBJECTIVE

To evaluate the relationship of 25-(OH)D concentration with the incidence of major clinical disease events that are pathophysiologically relevant to vitamin D.

DESIGN

Cohort study.

SETTING

The Cardiovascular Health Study conducted in 4 U.S. communities. Data from 1992 to 2006 were included in this analysis.

PARTICIPANTS

1621 white older adults.

MEASUREMENTS

Serum 25-(OH)D concentration (using a high-performance liquid chromatography-tandem mass spectrometry assay that conforms to National Institute of Standards and Technology reference standards) and associations with time to a composite outcome of incident hip fracture, myocardial infarction, cancer, or death.

RESULTS

Over a median 11-year follow-up, the composite outcome occurred in 1018 participants (63%). Defining events included 137 hip fractures, 186 myocardial infarctions, 335 incidences of cancer, and 360 deaths. The association of low 25-(OH)D concentration with risk for the composite outcome varied by season (P = 0.057). A concentration lower than a season-specific Z score of -0.54 best discriminated risk for the composite outcome and was associated with a 24% higher risk in adjusted analyses (95% CI, 9% to 42%). Corresponding season-specific 25-(OH)D concentrations were 43, 50, 61, and 55 nmol/L (17, 20, 24, and 22 ng/mL) in winter, spring, summer, and autumn, respectively.

LIMITATION

The observational study was restricted to white participants.

CONCLUSION

Threshold concentrations of 25-(OH)D associated with increased risk for relevant clinical disease events center near 50 nmol/L (20 ng/mL). Season-specific targets for 25-(OH)D concentration may be more appropriate than static targets when evaluating health risk.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Serum vitamin D levels are not predictive of the progression of chronic liver disease in hepatitis C patients with advanced fibrosis

In animal models and human cross-sectional studies, vitamin D deficiency has been associated with liver disease progression. Vitamin D supplementation has been suggested as a treatment to prevent disease progression. We sought to evaluate the role of vitamin D levels in predicting chronic liver disease development. We conducted a nested case-control study of vitamin D levels in subjects with (cases) and without (controls) liver histologic progression or clinical decompensation over the course of the HALT-C Trial. Vitamin D levels were measured at 4 points over 45 months. 129 cases and 129 aged-matched controls were included. No difference in baseline vitamin D levels were found between cases and controls. (44.8 ng/mL vs. 44.0 ng/mL, P = 0.74). Vitamin D levels declined in cases and controls over time (P = 0.0005), however, there was no difference in the level of decline (P = 0.37). Among study subjects with diabetes mellitius, baseline vitamin D levels were higher in cases, 49.9 ng/mL, than controls, 36.3 ng/mL. (P = 0.03) In addition, baseline vitamin D levels were higher in black case subjects, 32.7 ng/mL, than in black control subjects, 25.2 ng/mL (P = 0.08) No difference in vitamin D levels was found between patients with and without progression of hepatitis C-associated liver disease over 4 years. Our data do not suggest any role for vitamin D supplementation in patients with advanced chronic hepatitis C and raise the possibility that higher vitamin D levels may be associated with disease progression.

Serum vitamin D levels are not predictive of the progression of chronic liver disease in hepatitis C patients with advanced fibrosis

In animal models and human cross-sectional studies, vitamin D deficiency has been associated with liver disease progression. Vitamin D supplementation has been suggested as a treatment to prevent disease progression. We sought to evaluate the role of vitamin D levels in predicting chronic liver disease development. We conducted a nested case-control study of vitamin D levels in subjects with (cases) and without (controls) liver histologic progression or clinical decompensation over the course of the HALT-C Trial. Vitamin D levels were measured at 4 points over 45 months. 129 cases and 129 aged-matched controls were included. No difference in baseline vitamin D levels were found between cases and controls. (44.8 ng/mL vs. 44.0 ng/mL, P = 0.74). Vitamin D levels declined in cases and controls over time (P = 0.0005), however, there was no difference in the level of decline (P = 0.37). Among study subjects with diabetes mellitius, baseline vitamin D levels were higher in cases, 49.9 ng/mL, than controls, 36.3 ng/mL. (P = 0.03) In addition, baseline vitamin D levels were higher in black case subjects, 32.7 ng/mL, than in black control subjects, 25.2 ng/mL (P = 0.08) No difference in vitamin D levels was found between patients with and without progression of hepatitis C-associated liver disease over 4 years. Our data do not suggest any role for vitamin D supplementation in patients with advanced chronic hepatitis C and raise the possibility that higher vitamin D levels may be associated with disease progression.

Maternal serum levels of 25-hydroxy-vitamin D during pregnancy and risk of type 1 diabetes in the offspring

Previous studies indicate reduced risk of type 1 diabetes after intake of vitamin D supplements during pregnancy or early childhood. We aimed to test whether lower maternal serum concentrations of 25-hydroxy-vitamin D (25-OH D) during pregnancy were associated with an increased risk of childhood-onset type 1 diabetes. In this case-control study nested within a cohort of 29,072 women in Norway, 25-OH D levels were measured using a radioimmunoassay on samples from late pregnancy in 109 women delivering a child who developed type 1 diabetes before 15 years of age (case subjects) and from 219 control women. Dividing the levels of maternal 25-OH D into quartiles, there was a trend toward a higher risk of type 1 diabetes with lower levels of vitamin D during pregnancy. The odds of type 1 diabetes was more than twofold higher for the offspring of women with the lowest levels of 25-OH D compared with the offspring of those with levels above the upper quartile. Given future replication in independent cohorts, our findings provide support for the initiation of a randomized intervention trial to prevent type 1 diabetes in children by enhancing maternal 25-OH D status during pregnancy.

Seasonal variation in 25-hydroxyvitamin D concentrations in the cardiovascular health study

Low circulating concentrations of 25-hydroxyvitamin D (25(OH)D) are associated with adverse health outcomes in diverse populations. However, 25(OH)D concentrations vary seasonally with varying exposure to sunlight, so single measurements may poorly reflect long-term 25(OH)D exposure. The authors investigated cyclical trends in average serum 25(OH)D concentrations among 2,298 individuals enrolled in the Cardiovascular Health Study of community-based older adults (1992-1993). A sinusoidal model closely approximated observed 25(OH)D concentrations and fit the data significantly better than did a mean model (P < 0.0001). The mean annual 25(OH)D concentration was 25.1 ng/mL (95% confidence interval: 24.7, 25.5), and the mean peak-trough difference was 9.6 ng/mL (95% confidence interval: 8.5, 10.7). Male sex, higher latitude of study site, and greater physical activity levels were associated with larger peak-trough difference in 25(OH)D concentration (each P < 0.05). Serum concentrations of intact parathyroid hormone and bone-specific alkaline phosphatase also varied in a sinusoidal fashion (P < 0.0001), inversely to 25(OH)D. In conclusion, serum 25(OH)D varies in a sinusoidal manner, with large seasonal differences relative to mean concentration and laboratory evidence of biologic sequelae. Single 25(OH)D measurements might not capture overall vitamin D status, and the extent of misclassification could vary by demographic and behavioral factors. Accounting for collection time may reduce bias in research studies and improve decision-making in clinical care.

Vitamin D levels and risk of acute exacerbations of chronic obstructive pulmonary disease: a prospective cohort study

RATIONALE

Low blood levels of 25-hydroxyvitamin D (25[OH]D) have been associated with a higher risk of respiratory infections in general populations and higher risk of exacerbations of lung disease in people with asthma. We hypothesized that low blood levels of 25(OH)D in patients with chronic obstructive pulmonary disease (COPD) would be associated with an increased risk of acute exacerbations of COPD (AECOPD).

OBJECTIVES

To determine if baseline 25(OH)D levels relate to subsequent AECOPD in a cohort of patients at high risk for AECOPD.

METHODS

Plasma 25(OH)D was measured at baseline in 973 participants on entry to a 1-year study designed to determine if daily azithromycin decreased the incidence of AECOPD. Relationships between baseline 25(OH)D and AECOPD over 1 year were analyzed with time to first AECOPD as the primary outcome and exacerbation rate as the secondary outcome.

MEASUREMENTS AND MAIN RESULTS

In this largely white (85%) sample of North American patients with severe COPD (mean FEV(1) 1.12L; 40% of predicted), mean 25(OH)D was 25.7 ± 12.8 ng/ml. A total of 33.1% of participants were vitamin D insufficient (≥20 ng/ml but <30 ng/ml); 32% were vitamin D deficient (<20 ng/ml); and 8.4% had severe vitamin D deficiency (<10 ng/ml). Baseline 25(OH)D levels had no relationship to time to first AECOPD or AECOPD rates.

CONCLUSIONS

In patients with severe COPD, baseline 25(OH)D levels are not predictive of subsequent AECOPD. Clinical trial registered with www.clinicaltrials.gov (NCT00119860).

Midgestation maternal serum 25-hydroxyvitamin D level and soluble fms-like tyrosine kinase 1/placental growth factor ratio as predictors of severe preeclampsia

Recent studies have shown that low serum 25-hydroxyvitamin D (25[OH]D) level is a risk factor for preeclampsia. The clinical significance of in vitro findings that vitamin D regulates vascular endothelial growth factor production is unclear. We sought to determine whether there is an association between midgestation serum 25(OH)D levels and angiogenic factor activity and to compare their predictive value for the development of severe preeclampsia. We conducted a nested case-control study of women with severe preeclampsia (n=41) versus women with uncomplicated term birth (n=123) who had second trimester genetic screening (15-20 weeks). Using banked frozen serum, we measured levels of 25(OH)D, vascular endothelial growth factor, soluble fms-like tyrosine kinase 1, and placental growth factor and compared their correlations and predictive values. We found no correlation between serum 25(OH)D and angiogenic factors levels. 25(OH)D alone was comparable to vascular endothelial growth factor and soluble fms-like tyrosine kinase 1/placental growth factor ratio as a predictive marker for severe preeclampsia. A composite of both 25(OH)D level and soluble fms-like tyrosine kinase 1/placental growth factor ratio was more predictive than either alone (area under curve: 0.83 versus 0.74 and 0.67, respectively). In conclusion, combining midpregnancy 25(OH)D level with soluble fms-like tyrosine kinase 1/placental growth factor ratio provides a better prediction for the development of severe preeclampsia.

Serum 25-hydroxyvitamin D and change in estimated glomerular filtration rate

BACKGROUND AND OBJECTIVES

Mounting evidence suggests that 1,25-dihydroxyvitamin D prevents the progression of chronic kidney disease (CKD). It is not clear whether "nutritional" forms of vitamin D affect GFR.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We tested whether serum 25-hydroxyvitamin D concentration (25(OH)D), a measure of total vitamin D intake from cutaneous synthesis and dietary consumption, is associated with loss of estimated GFR among 1705 older adults with predominantly normal baseline kidney function participating in the Cardiovascular Health Study. Baseline 25(OH)D was measured by HPLC-tandem mass spectrometry. GFR was estimated at baseline and 4 years later using the CKD-EPI formula, with rapid GFR loss defined as 12 ml/min per 1.73 m(2) or more over 4 years.

RESULTS

Rapid GFR loss was observed for 207 participants (12%). Each 10 ng/ml lower 25(OH)D was associated with a 25% greater risk of rapid GFR loss (95% confidence interval [CI] 5%, 49%, P = 0.01), adjusting for potential confounding characteristics. Compared with 25(OH)D ≥30 ng/ml, 25(OH)D concentrations 15 to 29 ng/ml and <15 ng/ml were associated with 29% (95% CI -13%, 91%) and 68% (95% CI 1%, 177%) greater adjusted risks of rapid GFR loss, respectively. Magnitudes of association were largest among participants with diabetes.

RESULTS

were similar evaluating a composite outcome of rapid GFR loss, end stage renal disease, and death. Conclusions Insufficient 25(OH)D may be a modifiable risk factor for early GFR loss. We recommend clinical trials to determine whether vitamin D supplementation prevents the development and progression of CKD.

Vitamin D status and early age-related macular degeneration in postmenopausal women

OBJECTIVE

The relationship between serum 25-hydroxyvitamin D (25[OH]D) concentrations (nmol/L) and the prevalence of early age-related macular degeneration (AMD) was investigated in participants of the Carotenoids in Age-Related Eye Disease Study.

METHODS

Stereoscopic fundus photographs, taken from 2001 to 2004, assessed AMD status. Baseline (1994-1998) serum samples were available for 25(OH)D assays in 1313 women with complete ocular and risk factor data. Odds ratios (ORs) and 95% confidence intervals (CIs) for early AMD (n = 241) of 1287 without advanced disease were estimated with logistic regression and adjusted for age, smoking, iris pigmentation, family history of AMD, cardiovascular disease, diabetes, and hormone therapy use.

RESULTS

In multivariate models, no significant relationship was observed between early AMD and 25(OH)D (OR for quintile 5 vs 1, 0.79; 95% CI, 0.50-1.24; P for trend = .47). A significant age interaction (P = .002) suggested selective mortality bias in women aged 75 years and older: serum 25(OH)D was associated with decreased odds of early AMD in women younger than 75 years (n = 968) and increased odds in women aged 75 years or older (n = 319) (OR for quintile 5 vs 1, 0.52; 95% CI, 0.29-0.91; P for trend = .02 and OR, 1.76; 95% CI, 0.77-4.13; P for trend = .05, respectively). Further adjustment for body mass index and recreational physical activity, predictors of 25(OH)D, attenuated the observed association in women younger than 75 years. Additionally, among women younger than 75 years, intake of vitamin D from foods and supplements was related to decreased odds of early AMD in multivariate models; no relationship was observed with self-reported time spent in direct sunlight.

CONCLUSIONS

High serum 25(OH)D concentrations may protect against early AMD in women younger than 75 years.

Association of serum 25-hydroxyvitamin D (25-OHD) concentrations with maternal sex steroids and IGF-1 hormones during pregnancy

BACKGROUND

Vitamin D may influence circulating levels of sex steroid hormones in women during reproductive life, but associations in pregnant women have not been explored.

METHODS

Correlation and linear regression models were used to assess the association between sex steroids, (estradiol, progesterone, 17-hydroxyprogesterone, testosterone, and androstenedione), IGF-1, and serum 25-hydroxyvitamin D (25-OHD) concentrations during the first trimester of pregnancy in 106 cancer-free women from the Finnish Maternity Cohort.

RESULTS

There was no significant association of serum 25-OHD with any of the hormones measured. One-unit increase in serum 25-OHD concentration was associated with a non-significant 6% increase in estradiol concentrations. Multiparous women had higher levels of vitamin D (40.4 vs. 32.9 nmol/L, p-value = 0.01) than primiparous women.

CONCLUSION

Our study does not support an association between maternal serum 25-OHD levels and sex steroids or IGF-I concentrations during the first trimester of pregnancy.

Serum vitamin D levels and severe asthma exacerbations in the Childhood Asthma Management Program study

BACKGROUND

Asthma exacerbations, most often caused by respiratory tract infections, are the leading causes of asthma morbidity and comprise a significant proportion of asthma-related costs. Vitamin D status might play a role in preventing asthma exacerbations.

OBJECTIVES

We sought to assess the relationship between serum vitamin D levels and subsequent severe asthma exacerbations.

METHODS

We measured 25-hydroxyvitamin D levels in sera collected from 1024 children with mild-to-moderate persistent asthma at the time of enrollment in a multicenter clinical trial of children randomized to receive budesonide, nedocromil, or placebo (as-needed beta-agonists): the Childhood Asthma Management Program. Using multivariable modeling, we examined the relationship between baseline vitamin D levels and the odds of any hospitalization or emergency department visit over the 4 years of the trial.

RESULTS

Thirty-five percent of all subjects were vitamin D insufficient, as defined by a level of 30 ng/mL or less 25-hydroxyvitamin D. Mean vitamin D levels were lowest in African American subjects and highest in white subjects. After adjusting for age, sex, body mass index, income, and treatment group, insufficient vitamin D status was associated with a higher odds of any hospitalization or emergency department visit (odds ratio, 1.5; 95% CI, 1.1-1.9; P = .01).

CONCLUSION

Vitamin D insufficiency is common in this population of North American children with mild-to-moderate persistent asthma and is associated with higher odds of severe exacerbation over a 4-year period.