25-hydroxyvitamin D measurement, 2009: a review for clinicians

Vitamin D: A Bridge between Kidney and Heart

Chronic kidney disease (CKD) and cardiovascular disease (CVD) are highly prevalent conditions, each significantly contributing to the global burden of morbidity and mortality. CVD and CKD share a great number of common risk factors, such as hypertension, diabetes, obesity, and smoking, among others. Their relationship extends beyond these factors, encompassing intricate interplay between the two systems. Within this complex network of pathophysiological processes, vitamin D has emerged as a potential linchpin, exerting influence over diverse physiological pathways implicated in both CKD and CVD. In recent years, scientific exploration has unveiled a close connection between these two prevalent conditions and vitamin D, a crucial hormone traditionally recognized for its role in bone health. This article aims to provide an extensive review of vitamin D's multifaceted and expanding actions concerning its involvement in CKD and CVD.

Association between Vitamin D Levels and Nonalcoholic Fatty Liver Disease: Potential Confounding Variables

Nonalcoholic fatty liver disease (NAFLD), historically considered to be the hepatic component of the metabolic syndrome, is a spectrum of fat-associated liver conditions, in the absence of secondary causes, that may progress to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Disease progression is closely associated with body weight or fatness, dyslipidemia, insulin resistance, oxidative stress, and inflammation. Recently, vitamin D deficiency has been linked to the pathogenesis and severity of NAFLD because of vitamin D "pleiotropic" functions, with roles in immune modulation, cell differentiation and proliferation, and regulation of inflammation. Indeed, several studies have reported an association between vitamin D and NAFLD/NASH. However, other studies have failed to find an association. Therefore, we sought to critically review the current evidence on the association between vitamin D deficiency and NAFLD/NASH, and to analyze and discuss some key variables that may interfere with this evaluation, such as host-, environment-, and heritability-related factors regulating vitamin D synthesis and metabolism; definitions of deficient or optimal vitamin D status with respect to skeletal and nonskeletal outcomes including NAFLD/NASH; methods of measuring 25(OH)D; and methods of diagnosing NAFLD as well as quantifying adiposity, the cardinal link between vitamin D deficiency and NAFLD.

Side-Effects of Convulsive Seizures and Anti-Seizure Therapy on Bone in a Rat Model of Epilepsy

The severe sole effects of seizures on the cortical part of bone were reported in our previous study. However, the side effects of anti-epileptic drug therapy on bones has not been differentiated from the effects of the convulsive seizures, yet. This study provides the first report on differentiation of the effects of seizures and carbamazepine (a widely used antiepileptic drug) therapy on bones; 50 mg/kg/day drug was given to genetically induced absence epileptic rats for five weeks. Distinct bone regions including cortical, trabecular, and growth plate in each of tibia, femur, and spine tissues were studied using Fourier transform infrared (FT-IR) imaging and Vickers microhardness test. Blood levels of vitamin D and bone turnover biomarkers were also measured. According to the FT-IR imaging results, both seizure and carbamazepine-treated groups, more dominantly the drug-treated group, had lower mineral content with altered collagen crosslinks and higher crystallinity, implying reduced bone strength. Lower microhardness values also supported lower mechanical strength in bones. The most affected bone tissue and region from seizures and treatment was found as the spine and cortical, respectively. While there was a reduction in vitamin D and calcium levels in both seizure and carbamazepin-treated groups, significantly elevated PTH and bone turnover biomarkers were only seen in the drug-treated group.

Women with recurrent spontaneous abortion have decreased 25(OH) vitamin D and VDR at the fetal-maternal interface

Immunological mechanisms have been proposed to underlie the pathogenesis of recurrent spontaneous abortion (RSA). Vitamin D has a potent immunomodulatory effect, which may affect pregnancy outcome. The objective of this study was to investigate 25-hydroxyvitamin D [25(OH) D] concentration and vitamin D receptor (VDR) expression in the decidual tissues of RSA patients. Thirty women with RSA (RSA group) and thirty women undergoing elective abortion (control group) were recruited during 2016 from gynecology outpatient clinics. We measured 25(OH) D, interleukin (IL)-17, IL-23, transforming growth factor β (TGF-β), VDR and 1-α-hydroxylase (CYP27B1) in decidual tissues collected during the abortion procedure. In the RSA group, 25(OH) D and TGF-β were significantly decreased while IL-17 and IL-23 were significantly increased compared with the control group. VDR expression was significantly decreased in the RSA group compared with the control group. Logistic regression analysis showed a significant negative correlation between 25(OH) D in decidual tissues and RSA. These results indicated that vitamin D concentrations in the decidua are associated with inflammatory cytokine production, suggesting that vitamin D and VDR may play a role in the etiology of RSA.

Nutritional Vitamin D in Renal Transplant Patients: Speculations and Reality

Reduced levels of nutritional vitamin D are commonly observed in most chronic kidney disease (CKD) patients and particularly in patients who have received a kidney transplant (KTx). In the complex clinical scenario characterizing the recipients of a renal graft, nutritional vitamin D deficiency has been put in relation not only to the changes of mineral and bone metabolism (MBM) after KTx, but also to most of the medical complications which burden KTx patients. In fact, referring to its alleged pleiotropic (non-MBM related) activities, vitamin D has been claimed to play some role in the occurrence of cardiovascular, metabolic, immunologic, neoplastic and infectious complications commonly observed in KTx recipients. Furthermore, low nutritional vitamin D levels have also been connected with graft dysfunction occurrence and progression. In this review, we will discuss the purported and the demonstrated effects of native vitamin D deficiency/insufficiency in most of the above mentioned fields, dealing separately with the MBM-related and the pleiotropic effects.

Vitamin D Deficiency Among Professional Basketball Players

Background:

Vitamin D plays an important role in several systems of the human body. Various studies have linked vitamin D deficiency to stress and insufficiency fractures, muscle recovery and function, and athletic performance. The prevalence of vitamin D deficiency in the elite athletic population has not been extensively studied, and very few reports exist among professional athletes.

Hypothesis:

There is a high prevalence of vitamin D deficiency or insufficiency among players attending the National Basketball Association (NBA) Combine.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

This is a retrospective review of data previously collected as part of the routine medical evaluation of players in the NBA Combines from 2009 through 2013. Player parameters evaluated were height, weight, body mass index (BMI), and vitamin D level. Statistical analysis using t tests and analysis of variance was used to detect any correlation between the player parameters and vitamin D level. Vitamin D levels were categorized as deficient (<20 ng/mL), insufficient (20-32 ng/mL), and sufficient (>32 ng/mL).

Results:

After institutional review board approval was submitted to the NBA, the NBA released deidentified data on 279 players who participated in the combines from 2009 through 2013. There were 90 players (32.3%) who were deficient, 131 players (47.0%) who were insufficient, and 58 players (20.8%) who were sufficient. A total of 221 players (79.3%) were either vitamin D deficient or insufficient. Among all players included, the average vitamin D level was 25.6 ± 10.2 ng/mL. Among the players who were deficient, insufficient, and sufficient, the average vitamin D levels were 16.1 ± 2.1 ng/mL, 25.0 ± 3.4 ng/mL, and 41.6 ± 8.6 ng/mL, respectively. Player height and weight were significantly increased in vitamin D–sufficient players compared with players who were not sufficient (P = .0008 and .009, respectively). Player age and BMI did not significantly differ depending on vitamin D status (P = .15 and .77, respectively).

Conclusion:

There is a high prevalence of vitamin D deficiency or insufficiency among participants in the NBA Combines. As a result, there should be a high suspicion for this metabolic abnormality among elite basketball players.

Clinical Relevance:

Vitamin D level has been linked to bone health, muscle recovery and function, and athletic performance. Because of the high prevalence of vitamin D deficiency in the NBA Combines, clinicians should maintain a high suspicion for vitamin D abnormalities among elite basketball players.

Maternal-Cord Blood Vitamin D Correlations Vary by Maternal Levels

Vitamin D levels of pregnant women and their neonates tend to be related; however, it is unknown whether there are any subgroups in which they are not related. 25-Hydroxyvitamin D [25(OH)D] was measured in prenatal maternal and child cord blood samples of participants (n = 241 pairs) in a birth cohort. Spearman correlations were examined within subgroups defined by prenatal and delivery factors. Cord blood as a percentage of prenatal 25(OH)D level was calculated and characteristics compared between those who did and did not have ≥25% and ≥50% of the maternal level and those who did and did not have a detectable 25(OH)D level. The correlation among Black children was lower than in White children. When the maternal 25(OH)D level was <15 ng/mL, the overall correlation was r = 0.16. Most children had a 25(OH)D cord blood level less than half of their mother's; 15.4% had a level that was <25% of their mother's. Winter birth and maternal level were associated with the level being less than 25%. Children with undetectable levels were more likely to be Black and less likely to be firstborn. These data suggest mothers may reduce their contribution to the fetus's 25(OH)D supply once their own level becomes low.

Vitamin D status of psychiatric inpatients at a community teaching hospital in the Midwest

BACKGROUND

Vitamin D deficiency is a re-emerging epidemic in North America. It is increasingly linked to the pathology of cognition and mental illness and is also common in psychiatric patients.

AIMS

This study was designed to determine the prevalence of vitamin D deficiency among psychiatric inpatients in Kansas City, to explore the association between vitamin D status and clinical characteristics, and to identify the association of medical problems related to vitamin D deficiency in mental illness.

METHODS

In this descriptive study we recruited 52 psychiatric inpatients at a community teaching hospital in Kansas City between August and November 2013. A vitamin D-deficient state was defined as serum 25-hydroxyvitamin D (25-(OH) D) level ≤ 20 ng/mL. In addition to descriptive statistics, the Student t-test and Pearson test were used in the study.

RESULTS

A total of 15 patients (28.8%) were classified as deficient, 20 patients (38.5%) had an insufficiency, 17 patients (32.7%) were categorized as sufficient. Interestingly, there was a statistically significant difference in 25-(OH) D levels between African Americans and Caucasians (t = -2.216, p = 0.03) but no significant relationship between 25-(OH) D level and gender, major psychiatric diagnoses, type 2 diabetes mellitus or obesity. There was also no correlation between 25-(OH) D level and age, body mass index or haemoglobin A1C.

CONCLUSIONS

Low 25-(OH) D level was found in a high percentage of psychiatric inpatients in Kansas City. Screening for vitamin D deficiency could be a routine work-up for psychiatric inpatients. Vitamin D supplement for African American inpatients with low vitamin D levels could be considered.

Clinical implications of the HPV-16 infection & 7 beneficial effects of optimal dose of Vitamin D3 in safe, effective cancer treatment: Non-invasive rapid cancer screening using "Mouth, Hand & Foot Writing Form" of 40 participants during 150- minute workshop on the Bi-Digital 0-ring Test, in the 1st day of European Congress for Integrative Medicine, September 9-11, 2016 in Budapest

During the 1st day of European Congress for Integrative Medicine held September 9-11, 2016, almost the entire 1st day was scheduled for the Bi-Digital O-Ring Test, which was originally developed by this author, & consists of 2 main parts for which a U.S. patent was issued in 1993. One is a non-invasive, detection of various molecules using very strong Electromagnetic Field (EMF) Resonance Phenomenon between 2 identical molecules with identical weight. Using this strong EMF Resonance Phenomenon, most molecules & microorganisms can be detected rapidly and non-invasively without directly contacting patients. We measured the HPV-16 infection of 70 participants non-invasively in the first 30 minutes, then screened cancers for 40 volunteers who completed one page "Mouth, Hand & Foot Writing Form," which took an average of 5∼10 minutes for each person to complete. Screening of 75 common cancers was made in 2-5 minutes for each patient. Analysis of 40 volunteers revealed 32 persons had some malignancies including 5 Anaplastic Astrocytomas of the L-brain, 3 Multiple Myelomas, 7 Hodgkin's Lymphomas, 8 Non-Hodgkin's Lymphomas, 2 rectum cancers (with chief complaints of worsening Irritable Bowel Syndrome). Although everyone had HPV-16 infections between about 6,000ng & 250ng, malignancy could not be found among those who had less than 1,200ng. Our individualized safe, effective and economical treatment of various cancers consists of optimal doses of Vitamin D3 with or without Taurine and/or PQQ depending on the positive synergetic compatibility among these 3 substances as normal parts of human tissue. The most serious 2 cases of rectum cancer with multiple metastasis, we confirmed very significant anti-cancer effects of their optimal doses of vitamin D3, which is increased to 800~1,000 I.U. (due to advanced cancer with multiple metastasis instead of the usual 400 I.U. for average adults). The unique 7 beneficial effects of optimal dose of Vitamin D3 (also Taurine or PQQ) include: 1) significant Anti-cancer effects without side effects; 2) marked decrease in DNA mutation as decreases in 8-OH-dG; 3) marked urinary excretion of Viruses, Bacteria, Fungi, & Toxic substances, including Asbestos & metals; 4) marked increase in Acetylcholine in the brain & the rest of the body; 5) marked increase in DHEA; 6) marked decrease in β-Amyloid (I-42); 7) marked decrease in Cardiac Troponin I. Optimal dose of Vitamin D3 is clinically most important for cancer, ischemic heart, and memory problems. Optimal dose of Taurine is 150∼175mg and PQQ is 5-7.5mg and should be taken 3-4 times a day, depending on the patient. Medications and supplements including excessive Vitamin C (as well as multivitamins) but also inhibited optimal doses of Vitamin D3, Taurine & PQQ. Often coffee, drinks containing high Vitamin C content (e.g., some green tea & orange juice), & multivitamins as well as pain medicine (e.g., Oxycodone), strong EMF from cellular phones, and strong negative BDORT underwear often completely eliminate the above beneficial effects of Vitamin D3 and promote growth of cancer.

Association between vitamin D levels and allergy-related outcomes vary by race and other factors

BACKGROUND

Allergy-related studies that include biological measurements of vitamin D preceding well-measured outcomes are needed.

OBJECTIVE

We sought to examine the associations between early-life vitamin D levels and the development of allergy-related outcomes in the racially diverse Wayne County Health, Environment, Allergy, and Asthma Longitudinal Study birth cohort.

METHODS

25-Hydroxyvitamin D (25[OH]D) levels were measured in stored blood samples from pregnancy, cord blood, and age 2 years. Logistic regression models were used to calculate odds ratios (ORs) with 95% CIs for a 5 ng/mL increase in 25(OH)D levels for the following outcomes at age 2 years: eczema, skin prick tests (SPTs), increased allergen-specific IgE level (≥ 0.35 IU/mL), and doctor's diagnosis of asthma (3-6 years).

RESULTS

Prenatal 25(OH)D levels were inversely associated with eczema (OR, 0.85; 95% CI, 0.75-0.96). The association was stronger in white children (white children: OR, 0.79; 95% CI, 0.57-1.09; black children: OR, 0.96; 95% CI, 0.82-1.12), although this was not statistically significant. Cord blood 25(OH)D levels were inversely associated with having 1 or more positive SPT responses and aeroallergen sensitization. Both associations were statistically significant in white children (positive SPT response: OR, 0.50; 95% CI, 0.32-0.80; ≥ 1 aeroallergen sensitization: OR, 0.50; 95% CI, 0.28-0.92) in contrast with black children (positive SPT response: OR, 0.88; 95% CI, 0.68-1.14; ≥ 1 aeroallergen sensitization: OR, 0.85; 95% CI, 0.65-1.11). 25(OH)D levels measured concurrently with outcome assessment were inversely associated with aeroallergen sensitization (OR, 0.79; 95% CI, 0.66-0.96) only among black children (white children: OR, 1.21; 95% CI, 0.87-1.69).

CONCLUSIONS

Prenatal and cord blood 25(OH)D levels were associated with some allergy-related outcomes, with a general pattern indicating that children with higher 25(OH)D levels tend to have fewer allergy-related outcomes.

Is Preoperative Vitamin D Deficiency a Risk Factor for Postoperative Symptomatic Hypocalcemia in Thyroid Cancer Patients Undergoing Total Thyroidectomy Plus Central Compartment Neck Dissection?

BACKGROUND

Although some studies have reported that preoperative vitamin D deficiency (VDD) is a risk factor for hypocalcemia after total thyroidectomy (TT) in patients with nontoxic multinodular goiter or Graves' disease, the association between VDD and postoperative hypocalcemia in thyroid cancer patients undergoing TT plus central compartment neck dissection (CCND) remains unclear. This study evaluated whether preoperative VDD was associated with postoperative symptomatic hypocalcemia.

MATERIALS AND METHODS

Data were collected prospectively between September 2012 and May 2013. A total of 267 consecutive thyroid cancer patients who underwent TT with CCND were analyzed. Patients were divided into two groups--VDD or non-VDD--by preoperative vitamin D level of <10 or ≥10 ng/mL. Symptomatic hypocalcemia was defined as serum calcium <8.2 mg/dL and symptoms or signs of hypocalcemia. The rates of postoperative symptomatic hypocalcemia and clinicopathological features were compared between the two patient groups.

RESULTS

The rate of postoperative symptomatic hypocalcemia was higher in the VDD group than in the non-VDD group (43.8% vs. 30.4%, p=0.043). By logistic regression analysis, predictive factors for postoperative symptomatic hypocalcemia included a preoperative vitamin D level of <10 ng/mL (p=0.007; odds ratio=3.00). In patients who had postoperative intact parathyroid hormone (iPTH) levels <15 pg/mL, symptomatic hypocalcemia was more common in the VDD group than in the non-VDD group (77.5% vs. 53.2%, p=0.008). The findings show that a preoperative vitamin D threshold level of >20 ng/mL reduced the risk of symptomatic hypocalcemia by 72% when compared with patients with VDD (p=0.003).

CONCLUSION

VDD is significantly associated with postoperative symptomatic hypocalcemia in thyroid cancer patients undergoing TT plus CCND. VDD was predictive for symptomatic hypocalcemia when patients had postoperative serum iPTH levels <15 pg/mL. Thus, preoperative supplementation with oral vitamin D should be considered to minimize postoperative symptomatic hypocalcemia.

Measurement of 25-hydroxyvitamin D(2&3) and 1,25-dihydroxyvitamin D(2&3) by tandem mass spectrometry: A primate multispecies comparison

Vitamin D metabolites are widely studied for their roles in bone health, immune functions, and other potential physiologic roles in humans. However, the optimal blood levels of vitamin D metabolites are still unclear. Various methods for measuring vitamin D metabolites have been used and recently liquid chromatography tandem mass spectroscopy (LC-MS/MS) has been adopted as the gold standard for vitamin D metabolite measurement. Here, we report the use of LC-MS/MS to measure 25-hydroxyvitamin D (25(OH)D(2&3)), and 1,25-dihydroxyvitamin D (1,25(OH)2D(2&3)), in three laboratory nonhuman primate species: common marmoset (Callithrix jacchus), rhesus macaque (Macaca mulatta), and cynomolgus macaque (Macaca fascicularis), and compare them to humans using the same technique. The nonhuman primates showed blood levels for 25(OH)D3 and 1,25(OH)2D3 significantly higher than human values with marmosets having the highest levels. Marmoset samples showed significantly more variability among individuals than those from macaques for both metabolites, but all three nonhuman primate species exhibited large variation within species for both 25(OH)D(2&3) and 1,25(OH)2D(2&3). Marmoset females had significantly lower values than the males for 25(OH)D3, while rhesus males showed a significant decrease in 25(OH)D3 with age. The most striking finding is the variation within species for vitamin D levels even in laboratory primates that have a controlled diet, UV exposure, and in some cases, genetic constraints. Similar variation in 25(OH)D responses to a fixed dose of oral vitamin D supplementation has been reported in humans. We suggest that these species can provide primate models for examining the factors influencing variation in the levels of vitamin D necessary for human and nonhuman primate health.

Prevalence of 25-hydroxyvitamin D₂ in Western New York: a 3-year study

BACKGROUND

We evaluated the distribution of 25OH-D2 and 25OH-D3 in a general patient population in Western New York to provide insights into how common detectable vitamin D2 is among samples from a general patient population.

METHODS

Serum 25OH-D2 and 25OH-D3 results measured by LC-MS/MS from June 2009 to December 2012 were retrospectively analyzed.

RESULTS

A total of 266,269 serum tests were included for analysis. The percentage of tests with 25OH-D2 levels above the assay limit of quantitation (LoQ) decreased from 32% to 17% over the course of the study period. The percentage of tests with 25OH-D2 levels higher than those of 25OH-D3 decreased from 21% to 12%. Sixty-seven percent of the test results with 25OH-D2 levels above the LoQ had serum concentrations of 25OH-D2 higher than those of 25OH-D3.

CONCLUSION

Prevalence of tests with quantifiable 25OH-D2 decreased over time and yet 17% of them still had detectable levels of 25OH-D2, 67% of which had 25OH-D2 levels higher than 25OH-D3. To achieve accurate 25-hydroxyvitamin D measurement, clinical laboratories should assess the accuracy of their assays, and if necessary, determine the local prevalence of 25OH-D2 to determine if mass spectrometry is the platform of choice to assess vitamin D deficiency.

Skin cancer and vitamin D: an update

Exposure of the skin to solar ultraviolet (UV) radiation has both risks and benefits for human health. Absorption of UV-B radiation by DNA results in mutations that underlie the development of skin cancers, as is apparent from genetic studies showing high occurrence of UV signature mutations within these tumors. UV-B radiation is also absorbed by 7-dehydrocholesterol to initiate vitamin D synthesis. In experimental studies vitamin D metabolites enhance apoptosis of malignant cells, inhibit angiogenesis and proliferation and increase differentiation, potentially reducing skin cancer development and improving prognosis after diagnosis. There are some supporting human data. We review the links between sun exposure, vitamin D and skin cancers.

Building healthy bones throughout life: an evidence-informed strategy to prevent osteoporosis in Australia

Osteoporosis imposes a tremendous burden on Australia: 1.2 million Australians have osteoporosis and 6.3 million have osteopenia. In the 2007–08 financial year, 82 000 Australians suffered fragility fractures, of which > 17 000 were hip fractures. In the 2000–01 financial year, direct costs were estimated at $1.9 billion per year and an additional $5.6 billion on indirect costs. Osteoporosis was designated a National Health Priority Area in 2002; however, implementation of national plans has not yet matched the rhetoric in terms of urgency. Building healthy bones throughout life, the Osteoporosis Australia strategy to prevent osteoporosis throughout the life cycle, presents an evidence-informed set of recommendations for consumers, health care professionals and policymakers. The strategy was adopted by consensus at the Osteoporosis Australia Summit in Sydney, 20 October 2011. Primary objectives throughout the life cycle are: to maximise peak bone mass during childhood and adolescence to prevent premature bone loss and improve or maintain muscle mass, strength and functional capacity in healthy adults to prevent and treat osteoporosis in order to minimise the risk of suffering fragility fractures, and reduce falls risk, in older people. The recommendations focus on three affordable and important interventions — to ensure people have adequate calcium intake, vitamin D levels and appropriate physical activity throughout their lives. Recommendations relevant to all stages of life include: daily dietary calcium intakes should be consistent with Australian and New Zealand guidelines serum levels of vitamin D in the general population should be above 50nmol/L in winter or early spring for optimal bone health regular weight-bearing physical activity, muscle strengthening exercises and challenging balance/mobility activities should be conducted in a safe environment.

Determinants of vitamin D levels in men receiving androgen deprivation therapy for prostate cancer

PURPOSE

Studies found an association between decreased 25-OH vitamin D blood level and prostate cancer progression. Vitamin D supplementation is controversial and dosage recommendations inconsistent. This study identified factors associated with 25-OH vitamin D levels and whether vitamin D supplementation with 800 IU/day raised vitamin D levels in prostate cancer patients receiving androgen deprivation therapy (ADT).

DATA SOURCES

We recruited 108 men treated with ADT for ≥9 months from eight cancer and urology practices. Sections of the NHANES 2005-2006 questionnaire and Canadian Fitness Survey were completed identifying age, ethnicity, length of ADT use, calcium supplementation ≥1000 IU mg/day, body mass index, exercise, alcohol and tobacco use, and vitamin D supplementation ≥800 IU/daily. Blood was collected for 25-OH vitamin D analysis.

CONCLUSIONS

The majority of men (66%) had blood levels of 25-OH vitamin D <32 ng/mL. Regression analysis showed vitamin D supplementation (β = 6.556, CI 1.463, 11.650; p = .012) and African American ethnicity (β = -7.816, CI -12.996, -2.635; p = .003) is associated with 25-OH vitamin D level after controlling age and tobacco use.

PRACTICE IMPLICATIONS

Findings support current recommendations for supplementation with ≥800 IU vitamin D/day for men receiving ADT. Nurse practitioners caring for prostate cancer patients receiving ADT should include vitamin D monitoring and supplementation.

Methodological issues in assessing plasma 25-hydroxyvitamin D concentration in newborn infants

BACKGROUND

Although no gold standard exists, liquid chromatography tandem mass spectrometry (LC-MS/MS) is a precise and accurate method for the analysis of plasma 25-hydroxyvitamin D (25(OH)D). Immunoassays are more readily available and require small volume sampling, ideal for infant testing. The objective was to compare two commercially available immunoassays for measuring circulating 25(OH)D concentration in infant plasma against LC-MS/MS.

METHODS

Capillary blood samples from 103 infants were analyzed for plasma 25(OH)D using an enzyme immunoassay (EIA, Octeia, IDS Ltd.) and radioimmunoassay (RIA, DiaSorin). Plasma 25(OH)D(3), C-3 epimer of 25(OH)D(3) (3-epi-25(OH)D(3)) and 24,25-dihydroxyvitamin D (24,25(OH)(2)D(3)) were measured on the same samples using LC-MS/MS. To establish whether plasma 24,25(OH)(2)D(3) or 3-epi-25(OH)D(3) interferes with these immunoassay results, the zero 25(OH)D calibrator from each assay kit was spiked with increasing amounts of 24,25(OH)(2)D(3) or 3-epi-25(OH)D(3).

RESULTS

Classifying infants below the common vitamin D status targets of 50 nmol/L and 75 nmol/L respectively, 58% and 99% fell below using the RIA, 19% and 56% with the EIA and 31% and 76% with LC-MS/MS. Compared to LC-MS/MS, both immunoassays showed poor Bland-Altman limits of agreement for 25(OH)D concentrations (RIA: limits of agreement -27 to +13%; EIA: -12 to +41%), and mountain plots (folded cumulative distribution) depicted significant skew and bias. Spiked 24,25(OH)2D3 concentrations, but not 3-epi-25(OH)D3, appeared as >100% of known values on the EIA but not on the RIA thus, suggesting that the EIA may cross-react with 24,25(OH)(2)D(3) to a greater extent than 3-epi-25(OH)D(3).

CONCLUSION

Two common immunoassays resulted in very different classifications of vitamin D status possibly related to the interference of other vitamin D metabolites. Based on these data, LC-MS/MS assessment of vitamin D status is recommended in young infants (4-6 weeks of age).

Low 25-hydroxyvitamin D levels in people with a solid tumor cancer diagnosis: the tip of the iceberg?

PURPOSE

Low serum 25-hydroxyvitamin D [25(OH)D] levels have been linked to both cancer incidence and poor prognosis. The frequency of 25(OH)D tests and clinical factors associated with low levels in cancer patients are unknown.

PATIENTS AND METHODS

Electronic medical records from 2006 to 2007 of 39,252 adult solid tumor patients were reviewed. Data included demographics, cancer sites (primary and metastatic), and first serum 25(OH)D level during the study period. Laboratory data, comorbidities, selected medications, and anticancer treatment within the prior 2 months were recorded. Data were compared between (1) those tested and not tested and (2) 25(OH)D levels≤10 ng/ml (deficient), 11-30 ng/ml (insufficient), and ≥31 ng/ml (sufficient). Stepwise logistic regression identified independent predictors of low serum 25(OH)D levels.

RESULTS

The cohort was 86% Caucasian and 48% female with a mean age of 63±14 years (mean±SD). The most prevalent cancer was breast (19%). In total, 2,098 (5%) had a 25(OH)D test. Of those tested, 133 (6%) had levels≤10 ng/ml and 1,311 (62%) 11-30 ng/ml. Tests were more frequent in females and in those with breast, skin, and thyroid cancers (P<0.001). Low 25(OH)D levels were associated (in univariable analyses) with male gender, non-Caucasian race, gastrointestinal tumor primary sites, metastatic disease, benign liver disease, low serum albumin, and elevated liver enzymes. Significant factors in multivariable models for 25(OH)D levels≤10 and ≤30 ng/ml included non-Caucasian race, primary cancer site, and test calendar month. Vitamin D supplements and recent antineoplastic medication were associated with sufficient levels.

CONCLUSIONS

Low (deficient or insufficient) 25(OH)D serum levels were highly prevalent in people with solid tumors. Vitamin D tests were infrequent and paradoxically less often done in high-risk groups. Tests were more frequent in females and in those with breast, skin, and thyroid cancers. Further research should examine role of routine 25(OH)D tests, the clinical consequences of low levels, and therapeutic supplementation in people with cancer.

Vitamin D supplementation for prevention of mortality in adults

BACKGROUND

Available evidence on the effects of vitamin D on mortality has been inconclusive. In a recent systematic review, we found evidence that vitamin D3 may decrease mortality in mostly elderly women. The present systematic review updates and reassesses the benefits and harms of vitamin D supplementation used in primary and secondary prophylaxis of mortality.

OBJECTIVES

To assess the beneficial and harmful effects of vitamin D supplementation for prevention of mortality in healthy adults and adults in a stable phase of disease.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index-Expanded and Conference Proceedings Citation Index-Science (all up to February 2012). We checked references of included trials and pharmaceutical companies for unidentified relevant trials.

SELECTION CRITERIA

Randomised trials that compared any type of vitamin D in any dose with any duration and route of administration versus placebo or no intervention in adult participants. Participants could have been recruited from the general population or from patients diagnosed with a disease in a stable phase. Vitamin D could have been administered as supplemental vitamin D (vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol)) or as an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol) or 1,25-dihydroxyvitamin D (calcitriol)).

DATA COLLECTION AND ANALYSIS

Six review authors extracted data independently. Random-effects and fixed-effect meta-analyses were conducted. For dichotomous outcomes, we calculated the risk ratios (RRs). To account for trials with zero events, we performed meta-analyses of dichotomous data using risk differences (RDs) and empirical continuity corrections. We used published data and data obtained by contacting trial authors.To minimise the risk of systematic error, we assessed the risk of bias of the included trials. Trial sequential analyses controlled the risk of random errors possibly caused by cumulative meta-analyses.

MAIN RESULTS

We identified 159 randomised clinical trials. Ninety-four trials reported no mortality, and nine trials reported mortality but did not report in which intervention group the mortality occurred. Accordingly, 56 randomised trials with 95,286 participants provided usable data on mortality. The age of participants ranged from 18 to 107 years. Most trials included women older than 70 years. The mean proportion of women was 77%. Forty-eight of the trials randomly assigned 94,491 healthy participants. Of these, four trials included healthy volunteers, nine trials included postmenopausal women and 35 trials included older people living on their own or in institutional care. The remaining eight trials randomly assigned 795 participants with neurological, cardiovascular, respiratory or rheumatoid diseases. Vitamin D was administered for a weighted mean of 4.4 years. More than half of the trials had a low risk of bias. All trials were conducted in high-income countries. Forty-five trials (80%) reported the baseline vitamin D status of participants based on serum 25-hydroxyvitamin D levels. Participants in 19 trials had vitamin D adequacy (at or above 20 ng/mL). Participants in the remaining 26 trials had vitamin D insufficiency (less than 20 ng/mL).Vitamin D decreased mortality in all 56 trials analysed together (5,920/47,472 (12.5%) vs 6,077/47,814 (12.7%); RR 0.97 (95% confidence interval (CI) 0.94 to 0.99); P = 0.02; I(2) = 0%). More than 8% of participants dropped out. 'Worst-best case' and 'best-worst case' scenario analyses demonstrated that vitamin D could be associated with a dramatic increase or decrease in mortality. When different forms of vitamin D were assessed in separate analyses, only vitamin D3 decreased mortality (4,153/37,817 (11.0%) vs 4,340/38,110 (11.4%); RR 0.94 (95% CI 0.91 to 0.98); P = 0.002; I(2) = 0%; 75,927 participants; 38 trials). Vitamin D2, alfacalcidol and calcitriol did not significantly affect mortality. A subgroup analysis of trials at high risk of bias suggested that vitamin D2 may even increase mortality, but this finding could be due to random errors. Trial sequential analysis supported our finding regarding vitamin D3, with the cumulative Z-score breaking the trial sequential monitoring boundary for benefit, corresponding to 150 people treated over five years to prevent one additional death. We did not observe any statistically significant differences in the effect of vitamin D on mortality in subgroup analyses of trials at low risk of bias compared with trials at high risk of bias; of trials using placebo compared with trials using no intervention in the control group; of trials with no risk of industry bias compared with trials with risk of industry bias; of trials assessing primary prevention compared with trials assessing secondary prevention; of trials including participants with vitamin D level below 20 ng/mL at entry compared with trials including participants with vitamin D levels equal to or greater than 20 ng/mL at entry; of trials including ambulatory participants compared with trials including institutionalised participants; of trials using concomitant calcium supplementation compared with trials without calcium; of trials using a dose below 800 IU per day compared with trials using doses above 800 IU per day; and of trials including only women compared with trials including both sexes or only men. Vitamin D3 statistically significantly decreased cancer mortality (RR 0.88 (95% CI 0.78 to 0.98); P = 0.02; I(2) = 0%; 44,492 participants; 4 trials). Vitamin D3 combined with calcium increased the risk of nephrolithiasis (RR 1.17 (95% CI 1.02 to 1.34); P = 0.02; I(2) = 0%; 42,876 participants; 4 trials). Alfacalcidol and calcitriol increased the risk of hypercalcaemia (RR 3.18 (95% CI 1.17 to 8.68); P = 0.02; I(2) = 17%; 710 participants; 3 trials).

AUTHORS' CONCLUSIONS

Vitamin D3 seemed to decrease mortality in elderly people living independently or in institutional care. Vitamin D2, alfacalcidol and calcitriol had no statistically significant beneficial effects on mortality. Vitamin D3 combined with calcium increased nephrolithiasis. Both alfacalcidol and calcitriol increased hypercalcaemia. Because of risks of attrition bias originating from substantial dropout of participants and of outcome reporting bias due to a number of trials not reporting on mortality, as well as a number of other weaknesses in our evidence, further placebo-controlled randomised trials seem warranted.

Vitamin d status in central europe

Little published information is available regarding epidemiological data on vitamin D status in the large geographical region of Central Europe (CE). We searched the journal literature with regard to 25(OH)D concentrations among community-dwelling or healthy people living in CE. 25(OH)D concentrations varied by age, season, study sample size, and methodological approach [i.e., 25(OH)D assay used]. Concentrations of 25(OH)D in CE appeared lower than 30 ng/mL, and the magnitude of hypovitaminosis D was similar to that reported in Western Europe. While most of the studies reviewed were cross-sectional studies, a longitudinal study was also included to obtain information on seasonal variability. The longitudinal study reported wintertime 25(OH)D values close to 21-23 ng/mL for all studied age groups, with a significant increase of 25(OH)D in August reaching 42 ng/mL for those aged 0-9 years, but only 21 ng/mL for the elderly aged 80-89 years. The decrease in 25(OH)D with respect to age was attributed to decreased time spent in the sun and decreased vitamin D production efficiency. Based on the literature review on vitamin D status in the CE populations, it can be concluded that 25(OH)vitamin D levels are on average below the 30 ng/mL level.

Long-term bioavailability after a single oral or intramuscular administration of 600,000 IU of ergocalciferol or cholecalciferol: implications for treatment and prophylaxis

CONTEXT

We previously showed that a single high dose of oral (po) cholecalciferol (D₃) sharply increases serum 25-hydroxyvitamin D [25(OH)D].

OBJECTIVE

We evaluated the long-term bioavailability and metabolism of a single po or intramuscular (im) high dose of ergocalciferol (D₂) or D₃.

DESIGN

This was a prospective intervention study.

SETTING

The study was conducted in an ambulatory care setting.

PATIENTS

Participants were 24 subjects with hypovitaminosis D.

INTERVENTIONS

A single dose of 600,000 IU of po or im D₂ or D₃ was administered.

MAIN OUTCOME MEASURES

Serum 25(OH)D and 1,25-dihydroxyvitamin D [1,25(OH)₂D] were measured at baseline and at days 30, 60, 90, and 120 by RIA. Serum 1,25(OH)₂D₂, 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃], 24,25-hydroxyvitamin D₂ [24,25(OH)D₂], and 24,25-hydroxyvitamin D₃ [24,25(OH)D₃] were measured by liquid chromatography-tandem mass spectrometry in a subgroup of patients receiving the po formulations.

RESULTS

The areas under the curve of 25(OH)D after D₃ were significantly higher than those after D₂ (P < .0001). Serum 25(OH)D basal difference significantly increased at day 30 with po D₂ and D₃ (P < .01 and P < .0001) and up to day 90 with po D₃ (P < .01). The im formulations produced a slow increased, and values peaked at day 120 relative to the other time points (P < .0001). We found a decrease in 1,25(OH)₂D at day 30 (P < .05) and up to day 120 (P < .001) and an increase in 1,25(OH)₂D₂ at day 30 (P < .01) and up to day 120 (P < .01) after po D₂. Oral D₂ and D₃ produced increases in 24,25(OH)D₂ and 24,25(OH)D₃, respectively, at day 30 (P < .001).

CONCLUSIONS

A po dose of 600,000 IU of D₂ or D₃ is initially more effective in increasing serum 25(OH)D than the equivalent im dose and is rapidly metabolized. Our RIA assay for 1,25(OH)₂D may not recognize 1,25(OH)₂D₂.

Determinants of vitamin D status in fair-skinned women of childbearing age at northern latitudes

BACKGROUND AND OBJECTIVE

Poor vitamin D status during pregnancy has been associated with unfavorable outcomes for mother and child. Thus, adequate vitamin D status in women of childbearing age may be important. The aim of this study is to investigate the determinants of 25-hydroxyvitamin D (25(OH)D) serum concentrations in women of childbearing age living in Sweden, at latitude 57-58° north.

METHOD

Eighty four non-pregnant, non-lactating, healthy, fair-skinned women aged between 25-40 years were included. All subjects provided blood samples, four day food records and answered questionnaires about sun exposure and lifestyle. Total serum 25(OH)D was analyzed using Roche Cobas® electrochemoluminiescent immunoassay.

RESULTS

Mean 25(OH)D was 65.8±19.9 nmol/l and 23% of the subjects had concentrations <50 nmol/l. Only 1% had concentrations <25 nmol/l. Determinants of 25(OH)D concentrations were recent sunbed use, recent travel to southern latitude, season, estrogen contraceptive use and use of supplementary vitamin D (R(2) = 0.27).

CONCLUSION

Every fifth woman had 25(OH)D concentrations <50 nmol/l. About 30% of the variation in vitamin D status was explained by sun exposure, use of vitamin D supplements and use of estrogen contraceptives. Cutaneous vitamin D synthesis seems to be a major contributor to vitamin D status, even at northern latitudes. Thus, recommendations on safe UV-B exposure could be beneficial for vitamin D status.

Vitamin D assays: past and present debates, difficulties, and developments

Clinical interest in Vitamin D and its purported roles not only in calcium and bone metabolism but in several other medical conditions (diabetes, cardiovascular disease, multiple sclerosis, cancer, psychiatric disorders, neuro-muscular disease) has led to a surge in laboratory requests for 25 hydroxy vitamin D and 1,25 dihydroxy vitamin D measurement. Circulating 25 hydroxy vitamin D concentration is routinely used as the best indicator of vitamin D status, but measurement of other metabolites, especially the physiologically active 1,25 dihyroxy vitamin D, are of clinical value. Over the last 40 years the development of assays for vitamin D and its metabolites from early competitive binding assays through to immunoassay and liquid chromatography aligned to mass spectrometry have demonstrated various analytical challenges, the advantages and disadvantages of each method are constantly changing with new technological developments. Immunoassay remains the predominant mode of measurement for 25-hydroxy vitamin D although problems with equimolar recovery of the D2 and D3 metabolites remain an issue. Standardisation of all assays has been improved but not resolved with the currently available reference materials as evidenced by the international vitamin D external quality assurance scheme, DEQAS. The choice of method for each laboratory remains a balance mainly between turn around time, convenience, cost and the specificity and accuracy of the information obtained. With increasing discussion and clinical interest surrounding other vitamin D metabolites the vitamin D assay debate is set to continue.

Vitamin D, metabolic dyslipidemia, and metabolic syndrome in rheumatoid arthritis

PURPOSE

Vitamin D deficiency is a potential risk factor for cardiometabolic disease. We investigated the associations between vitamin D and dyslipidemia and the metabolic syndrome in patients with rheumatoid arthritis, a group at high risk for cardiovascular disease.

METHODS

Serum 25(OH)vitamin D and lipoprotein levels were measured at baseline in a random sample of 499 participants, ages 18-85 years, enrolled in a randomized trial of golimumab (GOlimumab Before Employing methotrexate as the First-line Option in the treatment of Rheumatoid arthritis of Early onset or GO-BEFORE Trial). Participants had rheumatoid arthritis with active disease, and were naïve to methotrexate and biologic therapies. Multivariable linear regression was performed to assess associations between vitamin D levels and lipoprotein fractions. Multivariable logistic regression was performed to determine the odds of hyperlipidemia and the metabolic syndrome in participants with vitamin D deficiency (<20 ng/mL).

RESULTS

In multivariable linear regression, vitamin D levels (per 10 ng/mL) were associated inversely with low-density lipoprotein (β: -0.029 [-0.049, -0.0091], P=.004) and triglyceride (β: -0.094 [-0.15, -0.039] P=.001) levels, adjusted for demographic, cardiovascular, and disease-specific variables. Vitamin D and high-density lipoprotein levels were not associated in univariate or multivariate analyses. Vitamin D deficiency was associated independently with an increased odds of hyperlipidemia (odds ratio 1.72; 95% confidence interval, 1.10-2.45; P=.014) and metabolic syndrome (odds ratio 3.45; 95% confidence interval, 1.75-6.80; P <.001) in adjusted models.

CONCLUSIONS

In conclusion, vitamin D deficiency was associated with the metabolic syndrome and dyslipidemia in rheumatoid arthritis, suggesting a potential role in cardiovascular disease risk. Large-scale, prospective studies are needed to determine if vitamin D supplementation improves lipoprotein levels and reduces cardiovascular risk in rheumatoid arthritis.

Osteoporosis in men: insights for the clinician

Osteoporosis has finally been recognized as an important disorder in men. Men have osteoporotic fractures about 10 years later in life than women. Owing to increasing life expectancy, more fractures are predicted. Important risk factors for men include advancing age, smoking or chronic obstructive pulmonary disease, glucocorticoid therapy, and androgen deprivation therapy for prostate cancer. Other groups at risk for osteoporosis include those with alcohol abuse, men on enzyme-inducing antiseizure drugs, and those with malabsorption or history of surgery for peptic ulcer disease. History and physical examination will likely reveal secondary causes of osteoporosis. Some, but not all organizations, recommend screening for osteoporosis in men older than age 70. In the USA, The Department of Veterans Affairs recommends case finding rather than screening. Evaluation starts with bone mineral density testing by dual energy X-ray absorptiometry of the spine, hip, and in some cases forearm. A few laboratory tests can be helpful, including measurement of 25-hydroxyvitamin D. Most studies of osteoporosis therapy in men are small; but alendronate, risedronate, zoledronic acid, and teriparatide are FDA-approved to increase bone density in men with osteoporosis. A new potent antiresorptive agent, denosumab, increased bone density dramatically in men on androgen deprivation therapy and is approved for this indication in Europe. Recognition, diagnosis, and treatment of osteoporosis in men should lead to fewer fractures and probably fewer deaths.

Vitamin D, calcium, and cardiovascular mortality: a perspective from a plenary lecture given at the annual meeting of the American Association of Clinical Endocrinologists

OBJECTIVE

To examine data showing associations between serum 25-hydroxyvitamin D levels and calcium intake and cardiovascular mortality.

METHODS

The articles reviewed include those published from 1992-2011 derived from search engines (PubMed, Scopus, Medscape) using the following search terms: vitamin D, calcium, cardiovascular events, cardiovascular mortality, all-cause mortality, vascular calcification, chronic kidney disease, renal stones, and hypercalciuria. Because these articles were not weighted (graded) on the level of evidence, this review reflects my own perspective on the data and how they should be applied to clinical management.

RESULTS

For skeletal health, vitamin D and calcium are both needed to ensure proper skeletal growth (modeling) and repair (remodeling). Nutritional deficiencies of either vitamin D or calcium may lead to a spectrum of metabolic bone disorders. Excessive consumption of either nutrient has been linked to a variety of medical disorders, such as hypercalcemia or renal stones. There have also been associations between vitamin D or calcium intake and cardiovascular disease. However, neither of these associations have established evidence nor known causality for increasing cardiovascular risk or all-cause mortality in patients with creatinine clearances greater than 60 mL/min. In patients with more severe chronic kidney disease, stronger data link excess calcium (or phosphorus) intake and increase in vascular calcification, but not mortality. The safe upper limit for vitamin D intake is at least 4000 IU daily and probably 10 000 IU daily; for calcium, the safe upper limit is between 2000 and 3000 mg daily.

CONCLUSIONS

While no solid scientific evidence validates that serum vitamin D levels between 15 and 70 ng/mL are associated with increased cardiovascular disease risk, stronger but inconsistent evidence shows an association between calcium supplementation greater than 500 mg daily and an increase in cardiovascular disease risk. Most professional societies suggest that replacement levels of these nutrients be personalized with the goal of reaching a 25-hydroxyvitamin D concentration between 30 and 50 ng/mL and a calcium intake of 1200 mg daily.

Vitamin d status and cardiometabolic risk factors in long-term psychiatric inpatients

OBJECTIVE

Low vitamin D levels are common in psychiatric patients, but a need for vitamin D supplementation in these individuals remains controversial. Low vitamin D levels are reportedly associated with high prevalence of cardiometabolic risk factors, and both are common in psychiatric patients, but the relationship between diagnosis and severity of illness and cardiometabolic risk status and the effect of vitamin D treatment on them is not known. We studied these relationships and effect of vitamin D(3) treatment on them in 290 long-term psychiatric inpatients.

METHOD

All patients admitted to the hospital during April 2009-March 2010 who agreed to 25-hydroxyvitamin-D testing were included. Serum 25-hydroxyvitamin D level, Brief Psychiatric Rating Scale (BPRS) score, body mass index, blood pressure, and fasting levels of blood glucose, triglycerides, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) were measured at baseline, and changes after vitamin D(3) treatment for up to 12 months were observed. For the purposes of this study, 25-hydroxyvitamin-D levels < 32 ng/mL were considered as "low"; < 20 ng/mL, as "insufficient"; and < 12 ng/mL, as "deficient."

RESULTS

A serum 25-hydroxyvitamin-D level < 32 ng/mL was found in 90.0% of patients, and a level <20 ng/mL was found in 48.6% of patients. A BPRS score > 36 was present in 56.0% of patients; obesity, in 75.7%; hypertension, in 44.8%; low HDL-C, in 43.6%; high triglycerides, in 31.2%; high LDL-C, in 17.8%; and increased glucose, in 14.6%. Serum 25-hydroxyvitamin-D levels correlated poorly with BPRS score and the other variables listed above (R, -0.02 to -0.22). After vitamin D(3) treatment, 25-hydroxyvitamin-D level increased to ≥ 20 ng/mL in all patients and ≥ 32 ng/mL in 85% of patients, but despite > 124% increase in mean 25-hydroxyvitamin-D level, mean improvement in other variables was < 12%.

CONCLUSIONS

Nearly half of our patients had vitamin D levels < 20 ng/mL, putting them at risk for poor bone health and requiring vitamin D supplementation. Cardiometabolic risk factors were also highly prevalent, but correlated poorly with vitamin D levels in their severity. Increasing vitamin D levels to ≥ 32 ng/mL was not associated with improvement in BPRS score or any cardiometabolic risk factor, emphasizing that intensification of therapeutic measures other than vitamin D supplementation is required.

Vitamin D and respiratory infection in adults

Vitamin D insufficiency is a global issue that has significant implications for health. The classical role of vitamin D in bone mineralisation is well known; vitamin D deficiency leads to rickets, osteomalacia or osteoporosis. The role of vitamin D in an immune system is less known. Vitamin D is not an actual vitamin but a secosteroid hormone produced in the skin from 7-dehydrocholesterol after exposure to sunlight UVB radiation. Nutrition and supplements are main sources of vitamin D in wintertime in northern countries as sunlight exposure is inadequate for the production. For activation vitamin D needs to be hydroxylated in liver to form 25-hydroxyvitamin D and in kidney to 1,25-dihydroxyvitamin D, the most active hormone in Ca absorption in the gut. For determination of vitamin D status serum 25-hydroxyvitamin D level, the major circulating form of the hormone is to be measured. Vitamin D regulates gene expression through binding with vitamin D receptors, which dimerises with retinoid X receptor. This complex binds to vitamin D-responsive elements inside the promoter regions of vitamin D-responsive genes. Vitamin D has a key role in innate immunity activation; the production of antimicrobial peptides (cathelicidin and defensins) following Toll-like receptor stimulation by pathogen lipopeptides is dependent on sufficient level of 25-hydroxyvitamin D. Clinically, there is evidence of the association of vitamin D insufficiency and respiratory tract infections. There is also some evidence of the prevention of infections by vitamin D supplementation. Randomised controlled trials are warranted to explore this preventive effect.

Overview of extraction methods for analysis of vitamin D and its metabolites in biological samples

In the last decade the scientific and medical community was confronted with a renewed interest in vitamin D and its metabolites, interest prompted by new discoveries regarding the association between members of the vitamin D family and a great number of physiological functions and pathological states. An impressive number of research projects have helped clear the path towards a better understanding of the functions of vitamin D and have resulted in the development of numerous methods of analysis. This review focuses on the various extraction methods used for analysis of vitamin D in research or clinical settings. Two main extractive methods are usually employed: liquid–liquid extraction and solid-phase extraction. Some methods use no extraction step and direct analysis is performed at the cost of significantly increased matrix interference. On the other hand, other methods use combined extraction techniques, and even additional derivatization steps in order to increase the sensitivity and accuracy of the analysis. The method of choice ultimately depends on the research question and the purpose of the study.

Associations of vitamin d binding protein gene polymorphisms with the development of peripheral arthritis and uveitis in ankylosing spondylitis

OBJECTIVE

Genetic factors account for more than 90% of overall susceptibility to ankylosing spondylitis (AS), and recent studies have focused on non-major histocompatibility complex genes. Vitamin D binding protein (DBP) is a highly polymorphic protein that transports vitamin D and its metabolites. In addition to its sterol binding capacity, DBP has many other roles in the inflammatory and immune systems, and has been reported to be associated with autoimmune diseases. We investigated the association between DBP polymorphisms and susceptibility to AS.

METHODS

This case-control study was conducted in 223 patients with AS and 239 ethnically matched controls who were genotyped for 8 single-nucleotide polymorphisms (SNP) in the DBP and its promoter. Genomic DNA was isolated from peripheral blood leukocytes using the standard phenolchloroform method, and the GoldenGate assay was used for genotyping.

RESULTS

No significant association was found between the susceptibility to AS and DBP polymorphisms. In a subgroup analysis of patients with AS, G alleles at rs222016 and rs222020 (OR 0.63, 95% CI 0.42-0.95, p = 0.03; OR 0.63, 95% CI 0.42-0.95, p = 0.03, respectively) and A allele at rs3733359 (OR 0.59, 95% CI 0.39-0.90, p = 0.01) showed the decreased risk of peripheral arthritis. G allele at rs4752 showed increased risk of uveitis (OR 2.04, 95% CI 1.12-3.72, p = 0.02). On the haplotype analyses, haplotype 2 (AGGA) protected against the development of peripheral arthritis (p = 0.01) and haplotype 3 (GAAG) was associated with an increased likelihood of uveitis (p = 0.02).

CONCLUSION

DBP gene polymorphisms are associated with the development of peripheral arthritis and uveitis in Korean patients with AS. Given the influence of different DBP variants on the immune system, larger-scale studies are warranted to elucidate the role of DBP in the pathogenesis of AS.

Association between night-shift work and serum 25-hydroxyvitamin D levels in Japanese male indoor workers: a cross-sectional study

Although low vitamin D status resulting from night work is a suspected cause of various health disorders, few studies have investigated the association between night-shift work and vitamin D status. Here, we examined serum 25-hydroxyvitamin D (25OHD) levels in 19 Japanese indoor workers, including night-shift workers, in blood samples collected at the annual medical checkup (late July) in a metal tool factory. Analyses were finally restricted to 14 male workers (33-59 yr) in 3 groups: fixed daytime work (n=6), and rotating shift work with (n=4) and without (n=4) night shifts. No significant differences in serum 25OHD levels were observed among the three groups (p=0.98, Kruskal-Wallis test). One to two participants in each group had 25OHD levels lower than the 20 ng/ml reference value for vitamin D deficiency even in summer. These results clearly indicate the need for large-scale studies to test the hypothesis that night-shift work is associated with lower 25OHD levels.

Maternal vitamin D during pregnancy and its relation to immune-mediated diseases in the offspring

Vitamin D deficiency during pregnancy is fairly common in many parts of the world. However, currently there is no consensus on the optimal vitamin D intake during pregnancy. Vitamin D is known to be of great importance for the homeostatic functions within the immune system. Maternal vitamin D status during pregnancy may therefore affect the developing immune system of the fetus, thus contributing to the later development of immune-mediated diseases. This chapter introduces the basics of vitamin D during pregnancy and discusses the role of maternal vitamin D intake in the development of asthma, allergic diseases, autoimmune diseases, cancer, and infections in the offspring. So far, the strongest observational evidence underlines the potential of maternal vitamin D intake during pregnancy to influence the likelihood of asthma and allergic outcomes in the offspring. Somewhat conflicting findings imply that there might be critical time windows of exposure to adequate vitamin D levels during pregnancy. More research is needed in order to fully understand the contribution of maternal vitamin D status during pregnancy to the progress of immune-mediated diseases.

Vitamin D supplementation for prevention of mortality in adults

BACKGROUND

The available evidence on vitamin D and mortality is inconclusive.

OBJECTIVES

To assess the beneficial and harmful effects of vitamin D for prevention of mortality in adults.

SEARCH STRATEGY

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science (to January 2011). We scanned bibliographies of relevant publications and asked experts and pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included randomised trials that compared vitamin D at any dose, duration, and route of administration versus placebo or no intervention. Vitamin D could have been administered as supplemental vitamin D (vitamin D(3) (cholecalciferol) or vitamin D(2) (ergocalciferol)) or an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol) or 1,25-dihydroxyvitamin D (calcitriol)).

DATA COLLECTION AND ANALYSIS

Six authors extracted data independently. Random-effects and fixed-effect model meta-analyses were conducted. For dichotomous outcomes, we calculated the risk ratios (RR). To account for trials with zero events, meta-analyses of dichotomous data were repeated using risk differences (RD) and empirical continuity corrections. Risk of bias was considered in order to minimise risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors.

MAIN RESULTS

Fifty randomised trials with 94,148 participants provided data for the mortality analyses. Most trials included elderly women (older than 70 years). Vitamin D was administered for a median of two years. More than one half of the trials had a low risk of bias. Overall, vitamin D decreased mortality (RR 0.97, 95% confidence interval (CI) 0.94 to 1.00, I(2) = 0%). When the different forms of vitamin D were assessed separately, only vitamin D(3) decreased mortality significantly (RR 0.94, 95% CI 0.91 to 0.98, I(2) = 0%; 74,789 participants, 32 trials) whereas vitamin D(2), alfacalcidol, or calcitriol did not. Trial sequential analysis supported our finding regarding vitamin D(3), corresponding to 161 individuals treated to prevent one additional death. Vitamin D(3) combined with calcium increased the risk of nephrolithiasis (RR 1.17, 95% CI 1.02 to 1.34, I(2) = 0%). Alfacalcidol and calcitriol increased the risk of hypercalcaemia (RR 3.18, 95% CI 1.17 to 8.68, I(2) = 17%). Data on health-related quality of life and health economics were inconclusive.

AUTHORS' CONCLUSIONS

Vitamin D in the form of vitamin D(3) seems to decrease mortality in predominantly elderly women who are mainly in institutions and dependent care. Vitamin D(2), alfacalcidol, and calcitriol had no statistically significant effect on mortality. Vitamin D(3) combined with calcium significantly increased nephrolithiasis. Both alfacalcidol and calcitriol significantly increased hypercalcaemia.

Vitamin D deficiency and seasonal and inter-day variation in circulating 25-hydroxyvitamin D and parathyroid hormone levels in indoor daytime workers: a longitudinal study

Seasonal variation in circulating 25-hydroxyvitamin D (25OHD) levels related to seasonal and inter-day fluctuation in sunlight ultraviolet irradiation, may lead to misjudgments concerning 25OHD status in individual workers around threshold levels. Here, to examine seasonal and inter-day variations in plasma 25OHD, we conducted a longitudinal study involving indoor daytime workers. Subjects were four male indoor daytime workers aged 32-57 yr working in Kawasaki City, Japan. Blood samples were obtained on six days within two two-week periods in February and October, 2008. Plasma 25OHD, serum intact parathyroid hormone (PTH) and 1α,25-dihydroxyvitamin D [1α,25(OH)(2)D] were measured. Individual monthly mean 25OHD levels were 16-56% higher in October than in February (p=0.03), while individual monthly mean intact PTH levels were 15-41% lower in October (p=0.09). No seasonal change was observed in 1α,25(OH)(2)D (p=0.62). Notably, nearly all measured 25OHD levels in February were lower than the reference value of 20 ng/ml. Our study identified the occurrence of seasonal variation in circulating 25OHD and intact PTH levels, even after accounting for inter-day variability, and hypovitaminosis D in wintertime in indoor daytime male workers in Japan. Due to this variability, single spot measurements of 25OHD may lead to misjudgment of workers' vitamin D status.

The Role of Vitamin D in Human Health: A Paradigm Shift

Vitamin D deficiency is pandemic, spanning many continents and including all ages, genders and racial/ethnic groups. Currently, world-wide attention is focused on the importance of vitamin D in optimizing health and preventing disease. This focus is largely the result of the scientific discovery that vitamin D receptors are present in nearly every tissue and cell in the body and that adequate vitamin D status is essential for optimal functioning of these tissues and cells. An impressive body of research has accumulated over the past two decades providing new information about the role of vitamin D in prevention of a broad range of diseases. The purpose of this paper is to provide a review of this new information.

Assessing vitamin D status: pitfalls for the unwary

The use of vitamin D testing has grown rapidly in the recent times as a result of increased interest in the role of vitamin D in health. Although the generally accepted measure of vitamin D status is circulating 25(OH)D concentration, there is little consensus on which assay method should be used. Commonly used assays include competitive protein-binding assay, RIA, enzyme immunoassay, chemiluminescence immunoassays, HPLC, and LC-MS/MS, each with its own advantages and disadvantages. However, there is significant interassay and interlaboratory variability in measurements. Our simulation of the published data showed that using a deficiency cut-point of 50 nmol/L, 57% of samples assessed using a chemiluminescence immunoassay were classified as deficient compared with 41% of samples assessed using LC-MS/MS; a 20% misclassification rate. Similar rates of misclassification were seen at 75 nmol/L. This has implications for clinical practice and decision limits for vitamin D supplementation, suggesting that cut-points should be assay specific rather than universal and that greater harmonization between laboratories is required. Newer assays using alternative biological samples to determine the circulating 25(OH)D have been proposed and advances in the genetics of vitamin D and the role of vitamin D-binding protein may improve future assay accuracy.

Should vitamin D status be assessed in patients with congestive heart failure?

For decades the vitamin D biological system has been considered almost exclusively as the master integrator of calcium-phosphate homeostasis and bone metabolism. More recently, the discovery that many human tissues and cells, which do not directly participate in mineral ion homeostasis, express the vitamin D receptor (VDR) and are able to convert the circulating pro-hormone 25-hydroxyvitamin D in its active form, 1,25-dihydroxyvitamin D, has provided new insights into the biological function of this peculiar endocrine system. Several reports have highlighted a variety of human diseases possibly related to vitamin D insufficiency or deficiency (respectively defined as 25-hydroxyvitamin D serum levels lower than 30 or lower than 20 ng/ml). In particular, experimental and observational studies, including those published in this journal issue, support the concept that vitamin D deficiency is involved in the pathogenesis of congestive heart failure, a disabling condition affecting over 15 million of patients worldwide. Considering that circulating levels of 25-hydroxyvitamin D represent the accepted clinical indicator of individual vitamin D status, the measurement of this pro-hormone can be regarded as an appropriate and cost-effective screening tool in patients with chronic heart failure.

Effect of a single oral dose of 600,000 IU of cholecalciferol on serum calciotropic hormones in young subjects with vitamin D deficiency: a prospective intervention study

CONTEXT

Effects of vitamin D repletion in young people with low vitamin D status have not been investigated so far.

OBJECTIVE

We evaluated the effect of a single massive dose of cholecalciferol on calcium metabolism at 3, 15, and 30 d, compared to baseline.

DESIGN AND SETTING

We conducted a prospective intervention study in an ambulatory care setting.

PARTICIPANTS

Forty-eight young subjects with vitamin D deficiency participated in the study.

INTERVENTION

A single oral dose of 600,000 IU of cholecalciferol was administered to each subject.

MAIN OUTCOME MEASURES

We evaluated serum changes of 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D, calcium, and PTH induced by a single load of cholecalciferol.

RESULTS

The 25(OH)D level was 15.8 ± 6.5 ng/ml at baseline and became 77.2 ± 30.5 ng/ml at 3 d (P < 0.001) and 62.4 ± 26.1 ng/ml at 30 d (P < 0.001). PTH levels concomitantly decreased from 53.0 ± 20.1 to 38.6 ± 17.2 pg/ml at 3 d and to 43.4 ± 14.0 pg/ml at 30 d (P < 0.001 for both). The trends were maintained in a subgroup followed up to 90 d (P < 0.001). Mean serum Ca and P significantly increased compared to baseline, whereas serum Mg decreased at 3 d. 1,25-Dihydroxyvitamin D significantly increased from 46.8 ± 18.9 to 97.8 ± 38.3 pg/ml at 3 d (P < 0.001) and to 59.5 ± 27.3 pg/ml at 60 d (P < 0.05).

CONCLUSIONS

A single oral dose of 600,000 IU of cholecalciferol rapidly enhances 25(OH)D and reduces PTH in young people with vitamin D deficiency.

Current status of clinical 25-hydroxyvitamin D measurement: an assessment of between-laboratory agreement

BACKGROUND

Historically, methodological differences and lack of standardization led to between-laboratory variability in 25(OH)D results. Recent observations raised concern about persisting variability. This quality assurance exercise investigated 25(OH)D result comparability between laboratories.

METHODS

Serum pools (n=25) were prepared to contain endogenous 25(OH)D(2) and 25(OH)D(3) at 25(OH)D concentrations from ~12 to 150 nmol/l (5-60 ng/ml). Aliquots were sent to 8 laboratories utilizing various 25(OH)D assay methods including high performance liquid chromatography with ultraviolet detection (LC-UV), LC with tandem mass spectroscopy detection (LC-MS/MS) or an automated immunoassay (Diasorin Liaison). The LC-UV results were selected as a referent to which all others were compared using linear regression and Bland-Altman analysis.

RESULTS

Good correlation (R(2)=0.87 to 0.97) was observed for all laboratories. Modest systematic bias was observed for some laboratories ranging from a positive mean bias of 10.5 nmol/l (4.2 ng/ml) to a negative mean bias of 3.5 nmol/l (1.4 ng/ml). For the laboratory with the greatest bias, 22/25 results were numerically higher (mean +15.7%) than LC-UV results. For Liaison, the primary error was likely random, whereas the major LC-MS/MS assay error source was biases likely due to calibration issues.

CONCLUSIONS

Modest inter-laboratory variability persists in serum 25(OH)D measurement. The National Institute of Standards and Technology 25(OH)D Standard Reference and calibration materials will further improve between-laboratory agreement for chromatography-based assays.

Vitamin D and pregnancy: An old problem revisited

Vitamin D has historically been considered to play a role solely in bone and calcium metabolism. Human disease associations and basic physiological studies suggest that vitamin D deficiency is plausibly implicated in adverse health outcomes including mortality, malignancy, cardiovascular disease, immune functioning and glucose metabolism. There is considerable evidence that low maternal levels of 25 hydroxyvitamin D are associated with adverse outcomes for both mother and fetus in pregnancy as well as the neonate and child. Vitamin D deficiency during pregnancy has been linked with a number of maternal problems including infertility, preeclampsia, gestational diabetes and an increased rate of caesarean section. Likewise, for the child, there is an association with small size, impaired growth and skeletal problems in infancy, neonatal hypocalcaemia and seizures, and an increased risk of HIV transmission. Other childhood disease associations include type 1 diabetes and effects on immune tolerance. The optimal concentration of 25 hydroxyvitamin D is unknown and compounded by difficulties in defining the normal range. Whilst there is suggestive physiological evidence to support a causal role for many of the associations, whether vitamin D deficiency is a marker of poor health or the underlying aetiological problem is unclear. Randomised controlled trials of vitamin D supplementation with an appropriate assessment of a variety of health outcomes are required.