Redefining vitamin D insufficiency

Vitamin D and bone health: What vitamin D can and cannot do

Historically vitamin D deficiency had devastating consequences for children causing rickets resulting in severe bone deformities often leading to death. The mystery of the cause of rickets finally came to light when it was observed that cod liver oil and sunlight could prevent and cure rickets. The first vitamin D to be discovered was vitamin D2 from ergosterol in ultraviolet irradiated yeast. Vitamin D3 was discovered from UV exposure to the skin. Investigations revealed the two major functions of vitamin D were to increase intestinal calcium and phosphate absorption and mobilize calcium from the skeleton to maintain calcium and phosphorus homeostasis. Later studies demonstrated that vitamin D does not have an active role in bone mineralization. Vitamin D deficiency results in secondary hyperparathyroidism increasing bone resorption. As a result, this decreases bone mineral content and compromises the architectural integrity increasing risk for fracture. Vitamin D deficiency has also been shown to enhance aging of the bone causing cracks and enhancing bone fractures. Vitamin D deficiency also causes osteomalacia. Therefore, vitamin D sufficiency is extremely important to maximize bone health throughout life. It helps to prevent bone loss, but it cannot restore bone loss due to increased bone resorption that can occur under a variety of circumstances including menopause. The Endocrine Society Guidelines recommends for all ages that adequate vitamin D obtained from the sun, foods and supplements is necessary in order to maintain a circulating concentration of 25-hydroxyvitamin D of at least 30 ng/mL for maximum bone health.

Effectiveness of Vitamin D and Alpha-Lipoic Acid in COVID-19 Infection: A Literature Review

Over three years since the World Health Organization (WHO) declared COVID-19 a pandemic, it is still a global burden. Vaccines against COVID-19, caused by SARS-CoV-2, are available and effective for preventing disease. However, their protective effects are not 100%. Currently, the U.S. Food and Drug Administration (FDA) has only approved a limited number of inpatient treatments for COVID-19, such as remdesivir, baricitinib, and tocilizumab. These medications have indications and contraindications applicable to a select patient population. Finding additional effective therapies that are widely available with limited risk could be vital in optimizing treatment strategies for this viral illness. Some vitamins and supplements have been identified as potential options for managing COVID-19. Vitamin D (VD) deficiency has been associated with respiratory tract infections. Moreover, alpha-lipoic acid (ALA) is a powerful antioxidant and helps reduce inflammatory responses in many pathologic conditions. This review aims to analyze the current evidence regarding the effectiveness of VD and alpha-lipoic acid in COVID-19 infection in both outpatient and hospitalized patients. Relevant randomized controlled trials (RCTs) were identified via the PubMed database from January 1, 2021, to December 31, 2023. Inclusion criteria were as follows: the study design was a randomized controlled trial (RCT), the usage of a constant dose during the intervention period without any additional boluses, and a research ethics committee approved it. Exclusion criteria included a lack of an outcome or apparent intervention, additional boluses, or a single-dose regimen in all the interventional groups. There were 11 studies with a total sample size of 35,717 patients that met the criteria for this review. A total of 10 RCTs examined the efficacy of VD, and one RCT that reviewed the efficacy of ALA was identified. All of the articles investigated the use of VD or ALA during the treatment of COVID-19. The endpoints of each study varied, including length of stay in hospital, viral load, SARS-CoV-2 infection rate, mechanical ventilation, inflammatory markers, clinical symptoms, Sequential Organ Failure Assessment (SOFA) score, and mortality. In 8/10 VD supplementation trials, significant differences were identified between the interventional and placebo groups in the aforementioned parameters. In 2/10 VD supplementation trials, no significant differences were identified. The ALA supplementation RCT found no differences between the interventional and placebo groups in the SOFA score and 30-day all-cause mortality rate. The current literature suggests that VD can potentially reduce the SARS-CoV-2 infection rate, oxygen requirements, inflammatory markers, clinical symptoms, and mortality. Regarding ALA, although there was a suggestion of benefit, it was not statistically significant. Common limitations among the different studies included relatively small sample sizes, different geographical patient locations among studies, and differences in dosages. Trials investigating the effects of higher doses of VD supplementation on SARS-CoV-2 infection should be conducted. More research is needed to define best practices and optimal dosing protocols for the use of VD in COVID-19.

Comparative Clinical Effects and Risk Factors Associated With Vitamin D in Foot and Ankle Fracture and Arthrodesis Healing

Vitamin D deficiency in relation to bone metabolism and healing has been controversial and not well studied. However, hypovitaminosis has been widely identified within the orthopedic patient population. The current best evidence suggests a lack of data on this important topic. The ability to assess patients for optimum bone healing and metabolism is still in question due to lack of a suitable reliable biomarker and multiple other unknown variables affecting bone metabolism. To compound this effect, popular dermatological precautions in the last 20 to 30 years of avoiding sunlight also have the effect of further reducing serum vitamin D production in the skin. As a proof of concept, we performed a preliminary comparative observational retrospective review of orthopedic patients undergoing fracture and arthrodesis osseous healing to determine how serum vitamin D levels are associated with bone healing along with their confounding comorbidities. Based on our review, the current accepted vitamin D levels (≥20 ng/mL) are low and insufficient for fractures and for arthrodesis osseous healing due to observed high rates (>35%) of delayed unions, and an increased (>90%) in the number of multiple confounding comorbidities affecting bone healing process that are often not mentioned or captured in this type of study in previous literature. Obesity and diabetes are significant contributory risks factors, and the preliminary findings suggest that the current accepted adequate levels may not be enough for osseous healing. These low vitamin D levels appear to affect bone healing and prolong treatment, with worsening trends with diabetes and obesity comorbidities.

Association of Low Vitamin D and Intact Parathyroid Hormone (iPTH) in Nepalese Population: When Does iPTH Exactly Rise?

Vitamin D deficiency is a global public health concern that provokes bone demineralization and weakening. In response to the decreased vitamin D level, calcium stores wear out. The homeostatic effect of compensatory hyperparathyroidism in vitamin D deficiency incites variable discrepancies in different populations. This study intends to decipher the transition point of PTH in relation to levels of vitamin D in a Nepalese population. A cross-sectional study was carried out at Tribhuvan University Teaching Hospital, Nepal. Serum calcium, phosphorus, intact PTH, and 25-hydroxy vitamin D levels were assayed in an Abbott ARCHITECT Integrated System. A correlation plot of PTH and vitamin D was analyzed in Statistical Package for Social Sciences version 22.0. Using a locally weighted scatter plot smoothing method, the relation between these variables was presented graphically. Among 281 individuals, 30.2% had vitamin D levels below 20 ng/mL. There was an archetypical transition in the PTH levels in concert with the decrease in vitamin D level marked by 2 inflection points (ie, 18.5 and 42.0 ng/mL). Our findings suggest that to augment overall health and avert weakness due to vitamin D deficiency, the levels of vitamin D should be maintained above 42.0 ng/mL in our population.

Vitamin D insufficiency in infants with increased risk of developing type 1 diabetes: a secondary analysis of the POInT Study

BACKGROUND

Vitamin D insufficiency (VDI) may be a factor in the development of type 1 diabetes (T1D). The aim of this study is to investigate the presence and persistence of VDI in a large cohort of infants with increased risk of developing T1D, in light of the differences in local supplementation guidelines.

METHODS

In the POInT Study, a multicentre primary prevention study between February 2018 and March 2021 in Germany, Poland, Belgium, England and Sweden, including infants aged 4-7 months at high genetic risk of developing β-cell autoantibodies, vitamin D levels were analysed at each study visit from inclusion (4-7 months) until 3 years, with an interval of 2 months (first three visits) or 4-6 months (visits 4-8). The protocol actively promotes vitamin D sufficiency to optimise immune tolerance. VDI was defined as a concentration below 30 ng/mL and was treated according to local guidelines of participating centres. Recovery from VDI was defined as a concentration above or equal to 30 ng/mL on the subsequent visit after VDI.

RESULTS

1050 infants were included, of which 5937 vitamin D levels were available for analyses. VDI was observed in 1464 (24.7%) visits and 507 (46.1%) of these were not resolved at the next visit. The risk of having VDI was independently associated with season (higher in winter), weight (higher with increased weight), age (higher with increased age) and country (higher in England). The risk of not recovering from VDI was independently associated with the season of the previously determined VDI, which was higher if VDI was identified in winter.

CONCLUSIONS

VDI is frequent in infants with increased risk of developing T1D. Treatment guidelines for VDI do not seem effective. Increasing supplementation dosages in this patient population seems warranted, especially during winter, and increasing dosages more aggressively after VDI should be considered.

Maternal Iron and Vitamin D Status during the Second Trimester Is Associated with Third Trimester Depression Symptoms among Pregnant Participants in the APrON Cohort

BACKGROUND

The maternal status of multiple micronutrients during pregnancy and postpartum and their potential associations with maternal health outcomes are largely undescribed.

OBJECTIVES

This study aimed to examine associations between maternal iron and vitamin D status, individually and in combination, on depression symptoms in pregnant individuals.

METHODS

The Alberta Pregnancy Outcomes and Nutrition cohort study included pregnant participants and their children from Calgary and Edmonton, Canada. Iron biomarkers (serum ferritin [SF], soluble transferrin receptor, and hepcidin) were measured via immunoassays and vitamin D [25-hydroxyvitamin D3 (25(OH)D3) and 3-epi-25-hydoxyvitamin D3 (3-epi-25(OH)D3)] metabolites were quantifed using liquid chromatography with tandem mass spectroscopy. Four categories of maternal iron and vitamin D status during the second trimester were conceptualized using concentrations of SF and total 25-hydoxyvitamin D [25(OH)D], respectively. Maternal Edinburgh Postnatal Depression Scale (EPDS) scores during the third trimester (n = 1920) and 3 mo postpartum (n = 1822) were obtained.

RESULTS

Concentrations of maternal 25(OH)D3, 3-epi-25(OH)D3, and the ratio of both metabolites were significantly higher during the second trimester compared with their status at 3 mo postpartum. Higher second trimester maternal concentrations of SF (β: -0.8; 95% confidence interval [CI]: -1.5, -0.01), hepcidin (β: -0.5; 95% CI: -0.9, -0.2), and 25(OH)D3 (β: -0.01; 95% CI: -0.02, -0.004) predicted lower maternal EPDS scores during the third trimester. Pregnant individuals with a low iron (SF <15 μg/L) and replete vitamin D (25(OH)D ≥75 nmol/L) (β: 1.1; 95% CI: 0.03, 2.1) or low iron (SF <15 μg/L) and vitamin D (25(OH)D <75 nmol/L) (β: 2.2; 95% CI: 0.3, 4.2) status during midpregnancy had higher third trimester EPDS scores compared with those that were replete in both micronutrients.

CONCLUSIONS

A higher midpregnancy maternal iron and vitamin D status, independently or in combination, predicted fewer maternal depression symptoms in the third trimester. Concentrations of maternal 25(OH)D3 and 3-epi-25(OH)D3 may be lower in the postpartum period compared with midpregnancy.

Predicting comorbidities of pregnancy: A comparison between total and free 25(OH)D and their associations with parathyroid hormone

Pregnancy is a unique time when amplified sex steroid concentrations promote an escalation in vitamin D binding protein (DBP) synthesis, associated with increased total vitamin D and metabolites, including 25-hydroxyvitamin D (25(OH)D). Free 25(OH)D concentration increases disproportionately to total 25(OH)D during pregnancy, likely an adaptation to supply the woman and fetus with readily available 25(OH)D. Highlighting the importance of the calcium metabolic stress during pregnancy, the interactional relationship between serum 25(OH)D and PTH has been evaluated. Maternal total 25(OH)D and total 25(OH)D/iPTH are measures of vitamin D status and biomarkers for potential pregnancy complications. It has been proposed that free 25(OH)D and free 25(OH)D/iPTH could be better indicators of vitamin D status and predictors of pregnancy complications such as gestational diabetes (GDM), hypertensive disorders of pregnancy, and preterm delivery. This study aims to determine if free 25(OH)D and its association with PTH are more accurate predictors of comorbidities of pregnancy than total 25(OH)D and its association with PTH. In this post hoc analysis of the Kellogg Pregnancy Study, a double-blind randomized placebo-controlled trial, participants included 297 women with singleton pregnancies: 191 participants were randomized into a group receiving a daily prenatal (400 IU vitamin D3) while 196 received a prenatal plus extra supplementation (4400 IU vitamin D3). Blood and urine samples were collected monthly. 297 participants' serum total 25(OH)D concentrations were measured using radioimmunoassay at baseline (visit 1) and 5-7 months' gestation (visit 6-7). 93 participants' serum free 25(OH)D and PTH concentrations were measured using ELISA and immunoradiometric assay, respectively, at visit 1 and 6-7; 66 participants had paired samples and were included in this analysis. Data were analyzed using SAS 9.4, Cary, N.C. or SPSS v28, IBM Corporation, Armonk, N.Y. Results were considered significant with a p < 0.05. A significant relationship exists between the ratio of total 25(OH)D/iPTH and free 25(OH)D/iPTH grouped by total 25(OH)D ≥ 30 ng/mL and < 30 ng/mL as an indicator of maternal vitamin D status. There was a statistically significant relationship between lower mean free 25(OH)D/iPTH and the development of GDM at visit 1 (p = 0.0003) and at visit 6-7 (p = 0.001) while total 25(OH)D/iPTH and GDM were significantly related only at visit 1 (p = 0.029). In this exploratory cohort, neither free 25(OH)D/iPTH nor total 25(OH)D/iPTH were significantly associated with increased incidence of preterm delivery, hypertensive disorders, or combined comorbidities of pregnancy. An univariate logistic regression evaluating the outcome of gestational diabetes while independently controlling for independent factors showed the ratio of free 25(OH)D/iPTH was more closely associated with gestational diabetes than the ratio of total 25(OH)D/iPTH, although neither were significant. This proof-of-concept analysis suggests that the ratio of free 25(OH)D/iPTH is associated with the development of gestational diabetes throughout pregnancy while total 25(OH)D/iPTH is only associated with the outcome early in pregnancy. Further investigation is warranted to explore this relationship between calcium metabolic stress during pregnancy with a larger cohort to improve validity,reproducibility, and relevance to other pregnancy comorbidities.

A randomized controlled trial of Vitamin D supplementation in Iranian patients with schizophrenia: Effects on serum levels of glycogen synthase kinase-3β and symptom severity

BACKGROUND

Growing evidence has shown that hypovitaminosis D is a risk factor for developing schizophrenia and comorbid conditions. Therefore, this study aimed to examine the effect of vitamin D supplementation on serum levels of vitamin D, metabolic factors related to insulin resistance (IR) and the severity of the disorder in patients with schizophrenia.

METHODS

Forty-eight chronic male patients with schizophrenia with vitamin D deficiency (≤20 ng/mL= (≤50 nmol/l) were selected and randomly assigned to vitamin D treatment and placebo groups. Subjects were supplemented for 8 weeks with vitamin D (2000 IU/day) or placebo.

RESULTS

Within-group comparison revealed that the vitamin D group had a significant reduction in waist circumference, Positive and Negative Syndrome Scale - total score (PANSS-TS), and glycogen synthase kinase 3 beta (GSK-3β) levels (P = .022, P = <.001 and P = .013, respectively). On the other hand, the placebo group showed a significant increase in the level of fasting serum insulin and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) (P = .003 and P = .003). The between-group comparison showed a significant difference in terms of PANSS-TS, GSK-3β, fasting serum insulin (FSI), and HOMA-IR (P = .022, P = .048, P = .013 and P = .014 respectively).

CONCLUSIONS

Among vitamin D deficient patients with schizophrenia, vitamin D supplementation may affect GSK-3 β, an important biomarker in schizophrenia and insulin resistance. In addition, vitamin D supplementation in such patients may reduce the disorder's symptom severity.

Loading dose vitamin D3 improves vitamin D insufficiency in adults undergoing hematopoietic stem cell transplantation: A randomized controlled trial

Allogeneic hematopoietic stem cell transplant (aHSCT) patients are well known to be at high risk of vitamin D (vit D) deficiency. This study assessed whether a loading dose (100,000 IU) of vitamin D3 pre-aHSCT could effectively achieve and maintain sufficient post-transplant vit D levels (serum total 25 hydroxy vitamin D (25(OH)D) ≥ 75nmol/L). Dual-energy X-ray absorptiometry (DXA) was also conducted for bone health evaluation. 74 patients were enrolled and randomly assigned, in a 1:1 ratio, either to the high vit D group (single loading dose (100,000 IU) plus 2,000 IU vit D3 daily) or the control group (2,000 IU vit D3 daily). Vit D levels were measured at three time points (baseline, day 30 and day 100 post-aHSCT). At baseline, fewer than 50% patients had a sufficient 25(OH)D (control: 42.9%; high vit D: 43.6%). The proportion of patients with sufficient 25(OH)D (nmol/L) was increased at day 30 and day 100, with a trend of higher proportion in the high vit D group at day 30 (high vit D vs. control: 89.7% vs. 74.3%, p = 0.08). The increased 25(OH)D was significantly higher in the high vit D group at day 30 (high vit D vs. control: 29±25.2 vs. 14 ±21.9, p = 0.01). Insufficient vit D level before transplant (baseline) was an independent risk factor for vit D insufficiency (serum 25(OH)D < 75nmol/L) post-aHSCT (OR = 4.16, p = 0.03). DXA suggested significant bone loss for total hip in both groups, and in the femoral neck for the control group only. In conclusion, single loading dose vitamin D3 significantly increased total 25(OH)D levels at day 30 post-transplant, and the intervention was especially beneficial for patients with baseline vit D insufficiency. We acknowledge that the primary outcome at day 100 post-aHSCT indicating superiority of loading dose versus daily dose supplementation was not met.

Health Effects of Vitamin D Supplementation: Lessons Learned From Randomized Controlled Trials and Mendelian Randomization Studies

Vitamin D plays an important role in calcium homeostasis and many cellular processes. Although vitamin D supplements are widely recommended for community-dwelling adults, definitive data on whether these supplements benefit clinically important skeletal and extraskeletal outcomes have been conflicting. Although observational studies on effects of vitamin D on musculoskeletal and extraskeletal outcomes may be confounded by reverse causation, randomized controlled studies (RCTs) and Mendelian randomization (MR) studies can help to elucidate causation. In this review, we summarize the recent findings from large RCTs and/or MR studies of vitamin D on bone health and risk of fractures, falls, cancer, and cardiovascular disease, disorders of the immune system, multiple sclerosis, and mortality in community-dwelling adults. The primary analyses indicate that vitamin D supplementation does not decrease bone loss, fractures, falls, cancer incidence, hypertension, or cardiovascular risk in generally healthy populations. Large RCTs and meta-analyses suggest an effect of supplemental vitamin D on cancer mortality. The existence of extraskeletal benefits of vitamin D supplementations are best documented for the immune system especially in people with poor vitamin D status, autoimmune diseases, and multiple sclerosis. Accumulating evidence indicates that vitamin D may reduce all-cause mortality. These findings, in mostly vitamin D-replete populations, do not apply to older adults in residential communities or adults with vitamin D deficiency or osteoporosis. The focus of vitamin D supplementation should shift from widespread use in generally healthy populations to targeted vitamin D supplementation in select individuals, good nutritional approaches, and elimination of vitamin D deficiency globally. © 2023 American Society for Bone and Mineral Research (ASBMR).

Effect of vitamin D supplementation on hormones and menstrual cycle regularization in polycystic ovary syndrome women: A systemic review and meta-analysis

AIM

Polycystic ovary syndrome (PCOS) is a prevalent endocrine disease among women of childbearing age. Women with PCOS frequently experience reproductive complications, which are closely associated with the concentration of vitamin D. This systemic review and meta-analysis were conducted to elucidate the possible effect of vitamin D supplementation in PCOS women on hormones, including Luteinizing hormone (LH), follicle-stimulating hormone (FSH), the ratio of LH and FSH (LH/FSH), and the menstrual cycle regularization.

METHODS

We searched PubMed, Web of Science, Ovid MEDLINE, Cochrane Library, and EMBASE for the relevant articles published up to January 2022. The pooled estimates were calculated using RevMan 5.4 software.

RESULTS

Twelve studies involving 849 PCOS patients were included. Our study indicated that vitamin D supplementation could reduce serum LH (standard mean difference [SMD]: -0.41; 95% confidence interval [CI]: -0.54, -0.28; p < 0.01). Subgroup analysis identified that the supplementation of vitamin D ≤4000 IU/day (SMD: -0.69; 95% CI: -1.15, -0.23; p < 0.01), treatment time ≤8 weeks (SMD: -0.61; 95% CI: -0.95, -0.26; p < 0.01), and vitamin D co-supplementation (SMD: -0.37; 95% CI: -0.65, -0.10; p < 0.01) were related to reduce serum LH level. In addition, vitamin D supplementation improved the regularity of menstrual cycle significantly (risk ratio [RR]: 1.35; 95% CI: 1.18, 1.54; p < 0.01). In stratified analysis, the significant effects only existed in dosage of vitamin D >4000 IU (RR: 1.62; 95% CI: 1.02, 2.57; p < 0.01), treatment time >8 weeks (RR: 1.41; 95% CI: 1.06, 1.87; p = 0.02) and vitamin D co-supplementation (RR: 1.18; 95% CI: 1.03, 1.35; p = 0.02). However, vitamin D might have no effects on serum FSH (SMD: -0.05; 95% CI: -0.42, 0.32; p = 0.79) and LH/FSH (SMD: -0.24; 95% CI: -0.55, 0.08; p = 0.14) in PCOS patients.

CONCLUSIONS

Evidence from the existing randomized controlled trials indicated that vitamin D supplementation might improve the LH level and the menstrual cycle regularization but did not have any effect on FSH and LH/FSH levels in PCOS patients.

Biochemical spectrum of parathyroid hormone disorders in patients attending Tribhuvan University Teaching Hospital, Kathmandu, Nepal

Objectives

This study intends to determine the association of parathormone with vitamin D and other biochemical parameters (calcium and phosphate) and evaluate the relationship between low vitamin D and parathormone levels.

Methods

A hospital-based cross-sectional study was conducted among 310 study participants over the period of 1 year. Patients who underwent laboratory investigations for vitamin D, parathormone, calcium, and phosphate in the Clinical Biochemistry Laboratory at the Institute of Medicine, Tribhuvan University Teaching Hospital were included. Serum intact parathyroid hormone, vitamin D, calcium, and phosphate were measured in Abbott Architect (ci4100) integrated system autoanalyzer.

Results

Among the 310 study participants, 177 (57%) were males and 43% were females. The mean age of the patient was 47.09 ± 19.01 years. High intact parathyroid hormone (>68 pg/ml) was observed in 73% of the patients. Low vitamin D (<20 ng/ml) was present in 30.2% of the patients. The findings from our study depict that there is a negative significant correlation between intact parathyroid hormone levels, vitamin D, and calcium levels and a positive correlation between intact parathyroid hormone and phosphate levels (p < 0.001).

Conclusions

The findings from our study illustrate that there is a swapping drift in the profile of hyperparathyroidism in the Nepalese population. We report the presence of hyperparathyroidism in the middle age group than in the older age group contradictory to that reported in the literature.

Inverse correlation of intact PTH, oxidized PTH as well as non-oxidized PTH with 25-hydroxyvitamin D3 in kidney transplant recipients

Background

25-hydroxyvitamin D (25(OH)D) and potentially also 1,25-dihydroxyvitamin D (1,25(OH)2D) inhibits the synthesis of parathyroid hormone (PTH) in the chief cells of the parathyroid gland. Clinical studies showing a negative correlation between (25(OH)D and PTH are in good agreement with these findings in basic science studies. However, PTH was measured in these studies with the currently clinically used 2nd or 3rd generation intact PTH (iPTH) assay systems. iPTH assays cannot distinguish between oxidized forms of PTH and non-oxidized PTH. Oxidized forms of PTH are the by far most abundant form of PTH in the circulation of patients with impaired kidney function. Oxidation of PTH causes a loss of function of PTH. Given that the clinical studies done so far were performed with an PTH assay systems that mainly detect oxidized forms of PTH, the real relationship between bioactive non-oxidized PTH and 25(OH)D as well as 1,25(OH)2D is still unknown.

Methods

To address this topic, we compared for the first time the relationship between 25(OH)D as well as 1,25(OH)2D and iPTH, oxPTH as well as fully bioactive n-oxPTH in 531 stable kidney transplant recipients in the central clinical laboratories of the Charité. Samples were assessed either directly (iPTH) or after oxPTH (n-oxPTH) was removed using a column that used anti-human oxPTH monoclonal antibodies, a monoclonal rat/mouse parathyroid hormone antibody (MAB) was immobilized onto a column with 500 liters of plasma samples. Spearman correlation analysis and Multivariate linear regression were used to evaluate the correlations between the variables.

Results

There was an inverse correlation between 25(OH)D and all forms of PTH, including oxPTH (iPTH: r=-0.197, p<0.0001; oxPTH: r=-0.203, p<0.0001; n-oxPTH: r=-0.146, p=0.001). No significant correlation was observed between 1,25(OH)2D and all forms of PTH. Multiple linear regression analysis considering age, PTH (iPTH, oxPTH and n-oxPTH), serum calcium, serum phosphor, serum creatinine, fibroblast growth factor 23 (FGF23), osteoprotegerin (OPG), albumin, and sclerostin as confounding factors confirmed these findings. Subgroup analysis showed that our results are not affected by sex and age.

Conclusion

In our study, all forms of PTH are inversely correlated with 25-hydroxyvitamin D (25(OH)D). This finding would be in line with an inhibition of the synthesis of all forms of PTH (bioactive n-oxPTH and oxidized forms of PTH with minor or no bioactivity) in the chief cells of the parathyroid glad.

Relationship between Vitamin D and Immunity in Older People with COVID-19

Vitamin D is a group of lipophilic hormones with pleiotropic actions. It has been traditionally related to bone metabolism, although several studies in the last decade have suggested its role in sarcopenia, cardiovascular and neurological diseases, insulin-resistance and diabetes, malignancies, and autoimmune diseases and infections. In the pandemic era, by considering the response of the different branches of the immune system to SARS-CoV-2 infection, our aims are both to analyse, among the pleiotropic effects of vitamin D, how its strong multimodal modulatory effect on the immune system is able to affect the pathophysiology of COVID-19 disease and to emphasise a possible relationship between the well-known circannual fluctuations in blood levels of this hormone and the epidemiological trend of this infection, particularly in the elderly population. The biologically active form of vitamin D, or calcitriol, can influence both the innate and the adaptive arm of the immune response. Calcifediol levels have been found to be inversely correlated with upper respiratory tract infections in several studies, and this activity seems to be related to its role in the innate immunity. Cathelicidin is one of the main underlying mechanisms since this peptide increases the phagocytic and germicidal activity acting as chemoattractant for neutrophils and monocytes, and representing the first barrier in the respiratory epithelium to pathogenic invasion. Furthermore, vitamin D exerts a predominantly inhibitory action on the adaptive immune response, and it influences either cell-mediated or humoral immunity through suppression of B cells proliferation, immunoglobulins production or plasma cells differentiation. This role is played by promoting the shift from a type 1 to a type 2 immune response. In particular, the suppression of Th1 response is due to the inhibition of T cells proliferation, pro-inflammatory cytokines production (e.g., INF-γ, TNF-α, IL-2, IL-17) and macrophage activation. Finally, T cells also play a fundamental role in viral infectious diseases. CD4 T cells provide support to B cells antibodies production and coordinate the activity of the other immunological cells; moreover, CD8 T lymphocytes remove infected cells and reduce viral load. For all these reasons, calcifediol could have a protective role in the lung damage produced by COVID-19 by both modulating the sensitivity of tissue to angiotensin II and promoting overexpression of ACE-2. Promising results for the potential effectiveness of vitamin D supplementation in reducing the severity of COVID-19 disease was demonstrated in a pilot clinical trial of 76 hospitalised patients with SARS-CoV-2 infection where oral calcifediol administration reduced the need for ICU treatment. These interesting results need to be confirmed in larger studies with available information on vitamin D serum levels.

Is the vitamin D status of patients with COVID-19 associated with reduced mortality? A systematic review and meta-analysis

To conduct a systematic review and meta-analysis of studies assessing the association between serum vitamin D status and mortality in patients with COVID- 19. We searched PubMed and Embase for studies addressing the association of serum vitamin D levels and COVID-19 mortality published until April 24, 2022. Risk ratios (RRs) and 95% confidence interval (CIs) were pooled using fixed or random effects models. The risk of bias was assessed using the Newcastle-Ottawa Scale. The meta-analysis included 21 studies that measured serum vitamin D levels close to the date of admission, of which 2 were case-control and 19 were cohort studies. Vitamin D deficiency was associated with COVID-19 mortality in the overall analysis but not when the analysis was adjusted to vitamin D cutoff levels < 10 or < 12 ng/mL (RR 1.60, 95% CI 0.93-2.27, I2 60.2%). Similarly, analyses including only studies that adjusted measures of effect for confounders showed no association between vitamin D status and death. However, when the analysis included studies without adjustments for confounding factors, the RR was 1.51 (95% CI 1.28-1.74, I2 0.0%), suggesting that confounders may have led to many observational studies incorrectly estimating the association between vitamin D status and mortality in patients with COVID-19. Deficient vitamin D levels were not associated with increased mortality rate in patients with COVID-19 when the analysis included studies with adjustments for confounders. Randomized clinical trials are needed to assess this association.

Association between the Triglyceride-Glucose Index and Vitamin D Status in Type 2 Diabetes Mellitus

BACKGROUND

Vitamin D deficiency (VDD) increases the risk for type 2 diabetes mellitus (T2DM), which might be related to insulin resistance (IR). We aimed to explore the association between the triglyceride-glucose (TyG) index, a reliable indicator of IR, and VDD in patients with T2DM.

METHODS

There were 1034 participants with T2DM enrolled in the Second Xiangya Hospital of Central South University. The TyG index was calculated as ln (fasting triglyceride (TG, mg/dL) × fasting blood glucose (mg/dL)/2). VDD was defined as 25-hydroxyvitamin D [25(OH)D] level <50 nmol/L.

RESULTS

Correlation analysis showed a negative association between the TyG index and 25(OH)D level. After adjustments for clinical and laboratory parameters, it was revealed that when taking the Q1 quartile of TyG index as a reference, an increasing trend of VDD prevalence was presented in the other three groups divided by TyG index quartiles, where the OR (95% CI) was 1.708 (1.132-2.576) for Q2, 2.041 (1.315-3.169) for Q3, and 2.543 (1.520-4.253) for Q4 (all p < 0.05).

CONCLUSIONS

Patients with higher TyG index were more likely to have an increased risk of VDD in T2DM population, which may be related to IR.

Osteomalacia

Osteomalacia with characteristic histomorphometric, radiographic, laboratory and clinical features is a prominent syndrome of disturbed bone mineralisation in adulthood. From an etiological point of view, osteomalacia is usually caused by substrate (calcium, phosphate) deficiency, presence of excess mineralization inhibitors or deficiency or ineffectivness of mineralization facilitator (vitamin D). In proportion to the high number of congenital and acquired causes of osteomalacia, its clinical and laboratory picture is heterogeneous and rarely fully expressed. The treatment of a particular case is determined by the cause of osteomalacia and may (but does not necessarily) include correction of the underlying disease, administration of calcium and various forms of vitamin D, as well as orthopaedic interventions. For some of the hereditary forms, biological or replacement therapy is prospectively available. The article attempts to cover the whole range of osteomalacia variants, mentioning a fact discussed only in recent years - the occurrence of oligosymptomatic, incompletely expressed forms.

The Effect of Vitamin D Level on Parathyroid Hormone and Alkaline Phosphatase

Over the years, we have noticed in our clinical practice that patients with 25-hydroxyvitamin D (25OHD) levels below 15 ng/mL are more symptomatic than those with higher levels. The aim of this research is to investigate changes in both parathyroid hormone (PTH) and alkaline phosphatase (ALP) at different vitamin D levels to determine if lower vitamin D levels are associated with more severe changes in PTH and ALP, which may explain the presence and severity of symptoms at those lower 25OHD levels. We looked for correlations between 25OHD level, PTH, and ALP in 1311 samples between 2015 and 2019 at our endocrine clinic to determine if vitamin D level correlates with changes in PTH and ALP. We further categorized vitamin D deficiency levels into three categories based on the severity of the reported symptoms. As expected, there were inverse but significant correlations between 25OHD, PTH, and ALP. The lower the 25OHD, the higher the PTH and ALP levels. When 25OHD was below 10 ng/mL, PTH was increased in 65% of the samples and ALP was elevated in 21% of the samples; however, PTH and ALP were normal in 70% and 87%, respectively, of patients with 25OHD levels between 15 < 20 ng/mL. The results support our clinical observations since most of the patients with 25OHD greater than 15 ng/mL had normal PTH and ALP, which may explain the lack of symptoms in these patients.

Vitamin D deficiency in dengue fever patients' coinfected with H. pylori in Pakistan. A case-control study

Introduction

Dengue fever is a vector-borne disease with an estimate of 390 million persons getting the infection each year with a significant public health impact. It has been reported DENV patients with vitamin D deficiency led to severe form of dengue infection; while H. pylori coinfection alters vitamin D receptors leading to vitamin D deficiency. We hypothesize that DENV patient's having low vitamin D along with H. pylori coinfection could have worsen dengue severity as well as vitamin D deficiency. In this case-control study, we compared (I) the vitamin D deficiency in dengue fever cases with or without H. pylori coinfection, and (II) negative dengue fever as a control with or without H. pylori coinfection. We have also assessed the correlation between vitamin D levels and its effect on warning signs of the dengue fever. Further, we have investigated whether coinfection with H. pylori has any effect on warning signs in the dengue fever patients and the vitamin D deficiency in all serotypes of the dengue virus infected patients.

Methods

In this case control study the association of the vitamin D levels with age, gender and H. pylori coinfection in dengue fever hospitalized patients was assessed using chi-square and multivariate logistic regression analysis.

Results

Four hundred dengue fever patients with H. pylori coinfection were compared with 400 dengue negative controls with H. pylori coinfection. The mean age was 29.96 ± 10.5 and 29.88 ± 10.7 years among cases and controls, respectively. Most dengue fever patients with H. pylori coinfection were deficient in vitamin D compared with negative dengue controls with H. pylori coinfection. In multivariate logistic regression, the dengue cases with H. pylori coinfection were.056 times (95% CI: 0.024, 0.128, P = 0.000) more likely to have vitamin D "deficiency', while compared with the cases who did not have H. pylori coinfection.

Conclusion

The present study proposes that vitamin D deficiency in dengue fever patients coinfected with H. pylori is much higher than the dengue fever negative controls coinfected with H. pylori. As hypothesized the DENV patient with H. pylori coinfection has vitamin D deficiency as well as increased dengue severity.

Reconsidering vitamin D optimal values based on parathyroid hormone levels in a North Algerian cohort: stratification by gender and season

"Health-based threshold value" is used to define the optimal cutoff of vitamin D. This approach is based on the hypothesis of a secondary hyperparathyroidism associated with hypovitaminosis D. We define the optimal values in a North Algerian population. The optimal value is 25.0 ng/ml in men and 30.0 ng/ml in women.

PURPOSE/INTRODUCTION

There is no consensus defining the vitamin D optimal values. The aim of this study is to establish vitamin D optimal values in the Northern Algerian population, based on its skeletal effects as represented by the inverse relationship between 25-hydroxy vitamin D (25(OH) D) and parathyroid hormone (PTH).

METHODS

451 healthy volunteers of both genders, aged 19 to 79 years, were enrolled in a cross-sectional study conducted at the medical analysis laboratory of the University Hospital of Blida, Algeria. 25(OH) D was assessed by a sequential competitive immuno-fluoroassay technique. Determination of vitamin D optimal values was performed based on the kinetic relationship between 25(OH) D and PTH, as explored by inverse nonlinear regression on a spline plots curve. The optimal value represents the 25(OH) D level at which PTH ceases to increase and reaches a virtual plateau.

RESULTS

In men and women, respectively, the 25 (OH) D thresholds are estimated at 25.0 ng/ml and 30 ng/ml, above this value, PTH stabilizes in a virtual plateau, estimated at 22.3 pg/ml and 26.8 pg/ml. In warm and cold seasons, respectively, the 25 (OH) D cut-offs are estimated at 30.0 ng/ml and 25.0 ng/ml, from these values, the PTH stabilizes in a virtual plateau, estimated at 21.5 pg/ml and 27.7 pg/ml.

CONCLUSION

In this study, the optimal values of 25(OH) D were defined for the first time in a North Algerian adult population. The optimal value is 25.0 ng/ml in men and 30.0 ng/ml in women.

Association of serum 25-hydroxyvitamin D (25(OH)D) levels with the gut microbiota and metabolites in postmenopausal women in China

Background

Vitamin D insufficiency or deficiency is associated with an altered microbiota in older men. However, the relationship between the gut microbiota and 25-hydroxyvitamin D (25(OH)D) levels remains unknown in postmenopausal women. In this study, fecal microbiota profiles for 88 postmenopausal women in the high 25(OH)D (HVD) group (n = 44) and the low 25(OH)D (LVD) group (n = 44) were determined. An integrated 16S rRNA gene sequencing and liquid chromatography–mass spectrometry (LC–MS)-based metabolomics approach was applied to explore the association of serum 25(OH)D levels with the gut microbiota and fecal metabolic phenotype. Adjustments were made using several statistical models for potential confounding variables identified from the literature.

Results

The results demonstrated that the community diversity estimated by the Observe, Chao1 and ACE indexes was significantly lower in the LVD group than in the HVD group. Additionally, two kinds of characteristic differences in the microflora were analyzed in the HVD group, and ten kinds of characteristic differences in the microflora were analyzed in the LVD group. We observed that some bacteria belonging to the genera Bifidobacterium, Bacillus, F0332 and Gemella, were enriched in the LVD group, as were other genera, including Lachnoclostridium, UC5_1_2E3, Ruminococcus_gnavus_group and un_f_Lachnospiraceae. Christensenellaceae, Eggerthellaceae and Cloacibacillus were enriched in the HVD group. The L-pyroglutamic acid, inosine, and L-homocysteic acid levels were higher in the HVD group and were negatively correlated with the 1,2-benzenedicarboxylic acid and cholic acid metabolic levels.

Conclusions

These observations provide a better understanding of the relationships between serum 25(OH)D levels and the fecal microbiota and metabolites in postmenopausal women.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-022-01858-6.

Vitamin D status and its association with parathyroid hormone in 23,134 outpatients

In vitro studies indicate that 25-hydroxyvitamin D3 (25(OH)D3) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) inhibits the synthesis of parathyroid hormone (PTH). The degree of PTH inhibition in humans by circulating 25(OH)D and 1,25(OH)2D may be different. Moreover, age and sex as well as confounding factors like calcium and phosphate may likewise affect the relationship between vitamin D and PTH in humans. However, this was not done so far in adequately powered studies. We investigated the relationship between 25(OH)D as well as 1,25(OH)2D and intact parathyroid hormone (iPTH) in 23,134 outpatients (age mean: 59.81 years) from the Berlin-Brandenburg area of Germany with normal serum creatinine considering confounding factors like age, sex, calcium and phosphate. 25(OH)D and iPTH were inversely correlated (r = -0.17, p < 0.0001). The inverse linear correlation was observed over the entire spectrum of 25(OH)D concentrations - from low 25(OH)D concentrations to very high 25(OH)D concentrations. Multiple linear regression analysis revealed that this correlation was independent of age, sex, creatinine, calcium and phosphate (unstandardized coefficients B: -0.16, p < 0.0001). However, 1,25(OH)2D was only positively associated with iPTH in women (r = 0.05, p = 0.033) and in the subgroup of patients with lower 25(OH)D (25(OH)D< 40 ng/ml) (r = 0.09, p < 0.0001), which was also presented in multiple linear regression analysis (unstandardized coefficients B: 0.20, p = 0.001). Circulating 1,25(OH)2D does not contribute substantially to the regulation of PTH in middle aged and vitamin D sufficient outpatients from the Berlin-Brandenburg area of Germany with normal kidney function. Presumably, serum 25(OH)D that is converted to 1,25(OH)2D after uptake in the parathyroid chief cells plays the critical role.

Applying Machine Learning to Determine 25(OH)D Threshold Levels Using Data from the AMATERASU Vitamin D Supplementation Trial in Patients with Digestive Tract Cancer

Some controversy remains on thresholds for deficiency or sufficiency of serum 25-hydroxyvitamin D (25(OH)D) levels. Moreover, 25(OH)D levels sufficient for bone health might differ from those required for cancer survival. This study aimed to explore these 25(OH)D threshold levels by applying the machine learning method of multivariable adaptive regression splines (MARS) in post hoc analyses using data from the AMATERASU trial, which randomly assigned Japanese patients with digestive tract cancer to receive vitamin D or placebo supplementation. Using MARS, threshold 25(OH)D levels were estimated as 17 ng/mL for calcium and 29 ng/mL for parathyroid hormone (PTH). Vitamin D supplementation increased calcium levels in patients with baseline 25(OH)D levels ≤17 ng/mL, suggesting deficiency for bone health, but not in those >17 ng/mL. Vitamin D supplementation improved 5-year relapse-free survival (RFS) compared with placebo in patients with intermediate 25(OH)D levels (18−28 ng/mL): vitamin D, 84% vs. placebo, 71%; hazard ratio, 0.49; 95% confidence interval, 0.25−0.96; p = 0.04. In contrast, vitamin D supplementation did not improve 5-year RFS among patients with low (≤17 ng/mL) or with high (≥29 ng/mL) 25(OH)D levels. MARS might be a reliable method with the potential to eliminate guesswork in the estimation of threshold values of biomarkers.

Vitamin D and Ocular Diseases: A Systematic Review

The contributory roles of vitamin D in ocular and visual health have long been discussed, with numerous studies pointing to the adverse effects of vitamin D deficiency. In this paper, we provide a systematic review of recent findings on the association between vitamin D and different ocular diseases, including myopia, age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), dry eye syndrome (DES), thyroid eye disease (TED), uveitis, retinoblastoma (RB), cataract, and others, from epidemiological, clinical and basic studies, and briefly discuss vitamin D metabolism in the eye. We searched two research databases for articles examining the association between vitamin D deficiency and different ocular diseases. One hundred and sixty-two studies were found. There is evidence on the association between vitamin D and myopia, AMD, DR, and DES. Overall, 17 out of 27 studies reported an association between vitamin D and AMD, while 48 out of 54 studies reported that vitamin D was associated with DR, and 25 out of 27 studies reported an association between vitamin D and DES. However, the available evidence for the association with other ocular diseases, such as glaucoma, TED, and RB, remains limited.

Characterization of Vitamin D Status in Older Persons with Cognitive Impairment

Vitamin D exerts a role in the maintenance of cognitive abilities and in frailty. Although several studies evaluated the interactions between vitamin D and cognitive impairment, results were conflicting. In a cohort of community-dwelling older persons, we described the association between vitamin D levels and cognitive decline and all-cause dementia evaluating frailty’s contribution. Our cohort included 509 adults, aged 64–92 years: 176 patients with mild cognitive impairment (MCI), 59 with Alzheimer’s Disease (AD), 26 with idiopathic Normal Pressure Hydrocephalus (iNPH), 133 with mixed dementia (MD) and 115 without cognitive decline. Frailty was measured by frailty index, and serum 25-hydroxyvitamin D concentrations through electrochemiluminescence immunoassays. We found a significant association between vitamin D levels and Mini Mental State Examination independently of cognitive impairment, age, sex and frailty. The patients with dementia (AD and MD) showed the lowest vitamin D levels, while MCI patients showed higher levels than the other groups. The most severe deficiency was observed in MD patients, the most aged as well as cognitively and functionally impaired. In conclusion, in our community-dwelling older persons investigated for a suspected cognitive impairment, we observed an association between vitamin D levels and cognitive decline, regardless of the frailty status.

Leukocyte telomere length as a compensatory mechanism in vitamin D metabolism

Vitamin D deficiency is common among postmenopausal women. Telomere length can be a potential protective mechanism for age-related diseases. The objective of our study is to examine the association of vitamin D supplementation on leukocyte telomere length (LTL) in healthy postmenopausal women with vitamin D deficiency. The study was designed as a placebo-controlled study to investigate the short-term effects of vitamin D supplementation and seasonal changes on vitamin D related parameters, including 25(OH)D, 1,25(OH)2D parathormone (PTH), Vitamin D binding protein (VDBP), vitamin D receptor (VDR), and telomere length in a cohort of postmenopausal women (n = 102). The group was divided as supplementation (n = 52) and placebo groups (n = 50). All parameters were measured before and after treatment. Serum VDBP levels were measured by ELISA method and VDR, GC (VDBP) gene expressions and relative telomere lengths were measured in peripheral blood mononuclear cells (PBMC) using a quantitative real-time PCR method. The results demonstrate that baseline levels were similar between the groups. After vitamin D supplementation 25(OH)D, 1,25(OH)2D, PTH and VDBP levels were changed significantly compared to the placebo group. At the end of the study period, LTL levels were significantly increased in both groups and this change was more prominent in placebo group. The change in GC expression was significant between treatment and placebo groups but VDR expression remained unchanged. Even though the study was designed to solely assess the effects of vitamin D supplementation, LTL was significantly increased in the whole study group in summer months suggesting that LTL levels are affected by sun exposure and seasonal changes rather than supplementation. The study displayed the short-term effect of Vitamin D supplementation on vitamin D, PTH levels, LTL and vitamin D associated gene expressions. The relation between Vitamin D and LTL is not linear and could be confounded by several factors such as the population differences, regional and seasonal changes in sun exposure.

Single bout of exercise triggers the increase of vitamin D blood concentration in adolescent trained boys: a pilot study

Vitamin D is necessary for musculoskeletal health, however, the supplementation of vitamin D above the sufficiency level does not bring additional bone mass density (BMD), unlike physical exercise which enhances the bone formatting process. Regular physical activity has been shown to upregulate VDR expression in muscles and to increase circulating vitamin D. Here we investigate whether a single bout of exercise might change 25(OH)D₃ blood concentration and how it affects metabolic response to exercise. Twenty-six boys, 13.8 years old (SD ± 0.7) soccer players, participated in the study. The participants performed one of two types of exercise: the first group performed the VO₂max test until exhaustion, and the second performed three times the repeated 30 s Wingate Anaerobic Test (WAnT). Blood was collected before, 15 min and one hour after the exercise. The concentration of 25(OH)D₃, parathyroid hormone (PTH), interleukin-6 (IL-6), lactate, non-esterified fatty acids (NEFA) and glycerol were determined. 25(OH)D₃ concentration significantly increased after the exercise in all boys. The most prominent changes in 25(OH)D₃, observed after WAnT, were associated with the rise of PTH. The dimensions of response to the exercises observed through the changes in the concentration of 25(OH)D₃, PTH, NEFA and glycerol were associated with the significant increases of IL-6 level. A single bout of exercise may increase the serum’s 25(OH)D₃ concentration in young trained boys. The intensive interval exercise brings a more potent stimulus to vitamin D fluctuations in young organisms. Our results support the hypothesis that muscles may both store and release 25(OH)D₃.

The effects of season (spring versus autumn) on diagnosis of normocalcemic primary hyperparathyroidism

BACKGROUND

Raised parathormone (PTH) and normal calcium concentrations can be observed both in normocalcemic primary hyperparathyroidism (nPHPT) and in secondary hyperparathyroidism, e.g. due to vitamin D deficiency. We assessed the impact of season on the validity of diagnosis of nPHPT in terms of screening investigations to be performed in the primary care settings.

MATERIAL AND METHODS

On two occasions (March/April & September/October) we measured vitamin D (25OHD), PTH and total calcium in 125 healthy subjects, age range 6-50, not taking any vitamin D supplements.

RESULTS

In autumn there was an increase in 25OHD concentrations (from 18.1 ± 7.37ng/ml to 24.58 ± 7.72ng/ml, p<0.0001), a decline in PTH from 44.40 ± 17.76pg/ml to 36.63 ± 14.84pg/ml, p<0.001), without change in calcium levels. Only 45 subjects (36%) were vitamin D sufficient (25OHD>20/ml) in spring versus 83 (66.4%) in autumn, p<0.001. Elevated PTH concentrations were noted in 10 subjects in spring (8%) and in six subjects (4.8%) (p<0.05) in autumn. In spring, however, eight out of ten of these subjects (80%) had 25OHD<20 ng/ml, versus one in six (16.7%) in autumn (p<0.01). Normalization of PTH was observed in seven out ten subjects (70%), and all of them had 25-OHD<20 ng/ml in spring.

CONCLUSIONS

In spring elevated PTH concentrations in the setting of normocalcemia are more likely to be caused by 25OHD deficiency rather by nPHPT. In contrast, in autumn, increased PTH concentrations are more likely to reflect nPHPT. We postulate that screening for nPHPT should be done in 25OHD replete subjects, i.e. in autumn rather than in spring.

Vitamin D deficiency and associated factors in south Korean childbearing women: a cross-sectional study

Background

Adequate levels of vitamin D are important for women of childbearing age as vitamin D helps maintain the pregnancy and ensures proper maternal and fetal bone metabolism and fetal skeletal development. However, vitamin D deficiency is a health problem prevalent in women of all ages, worldwide. This study aimed to determine the current status of serum vitamin D levels and the risk factors for vitamin D deficiency among South Korean nurses of childbearing age.

Methods

Serum levels of 25-hydroxyvitamin D (25[OH]D) were measured in 1594 registered nurses aged 20 to 45 years who are participants in an ongoing prospective cohort study of the Korean Nurses’ Health Study initiated in 2013. The participants completed surveys about demographic and occupational characteristics and physical and psychological health. We examined associations with vitamin D deficiency through multivariable logistic regression analysis.

Results

The average blood 25(OH) D concentration of the participants was 12.92 ng/mL (4.0–63.4 ng/mL), while the prevalence of vitamin D deficiency (< 20 ng/mL) was 89% (1419/1594). Multivariable logistic regression showed that significant risk factors for vitamin D deficiency included month of sampling (there was a lower level of vitamin D deficiency in winter than in spring, summer, or fall), age (women in their 20s had a lower vitamin D level than those in their 30s and 40s), and stress symptoms. Vitamin D levels were not associated with body mass index, physical activity, and depressive symptoms.

Conclusions

This study showed a high prevalence of vitamin D deficiency in Korean female nurses. Serum levels of vitamin D were associated with age and season. Vitamin D deficiency should be recognized as one of the primary health concerns among young women. More proactive actions, such as vitamin D supplements and food fortification, are needed to improve vitamin D deficiency in high-risk groups.

Vitamin D insufficiency in COVID-19 and influenza A, and critical illness survivors: a cross-sectional study

OBJECTIVES

The steroid hormone vitamin D has roles in immunomodulation and bone health. Insufficiency is associated with susceptibility to respiratory infections. We report 25-hydroxy vitamin D (25(OH)D) measurements in hospitalised people with COVID-19 and influenza A and in survivors of critical illness to test the hypotheses that vitamin D insufficiency scales with illness severity and persists in survivors.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

Plasma was obtained from 295 hospitalised people with COVID-19 (International Severe Acute Respiratory and emerging Infections Consortium (ISARIC)/WHO Clinical Characterization Protocol for Severe Emerging Infections UK study), 93 with influenza A (Mechanisms of Severe Acute Influenza Consortium (MOSAIC) study, during the 2009-2010 H1N1 pandemic) and 139 survivors of non-selected critical illness (prior to the COVID-19 pandemic). Total 25(OH)D was measured by liquid chromatography-tandem mass spectrometry. Free 25(OH)D was measured by ELISA in COVID-19 samples.

OUTCOME MEASURES

Receipt of invasive mechanical ventilation (IMV) and in-hospital mortality.

RESULTS

Vitamin D insufficiency (total 25(OH)D 25-50 nmol/L) and deficiency (<25 nmol/L) were prevalent in COVID-19 (29.3% and 44.4%, respectively), influenza A (47.3% and 37.6%) and critical illness survivors (30.2% and 56.8%). In COVID-19 and influenza A, total 25(OH)D measured early in illness was lower in patients who received IMV (19.6 vs 31.9 nmol/L (p<0.0001) and 22.9 vs 31.1 nmol/L (p=0.0009), respectively). In COVID-19, biologically active free 25(OH)D correlated with total 25(OH)D and was lower in patients who received IMV, but was not associated with selected circulating inflammatory mediators.

CONCLUSIONS

Vitamin D deficiency/insufficiency was present in majority of hospitalised patients with COVID-19 or influenza A and correlated with severity and persisted in critical illness survivors at concentrations expected to disrupt bone metabolism. These findings support early supplementation trials to determine if insufficiency is causal in progression to severe disease, and investigation of longer-term bone health outcomes.

Association between circulating 25-hydroxyvitamin D concentrations and hip replacement for osteoarthritis: a prospective cohort study

BACKGROUND

To examine the association between circulating 25(OH)D concentrations and incidence of total hip replacement for osteoarthritis in a prospective cohort study.

METHODS

This study examined a random sample of 2651 participants in the Melbourne Collaborative Cohort Study who had 25(OH)D concentrations measured from dried blood spots collected in 1990-1994. Participants who underwent total hip replacement for osteoarthritis between January 2001 and December 2018 were identified by linking the cohort records to the Australian Orthopaedic Association National Joint Replacement Registry. Cox proportional hazard regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) of total hip replacement for osteoarthritis in relation to 25(OH)D concentrations, adjusted for confounders.

RESULTS

Eighty-six men and eighty-seven women had a total hip replacement for osteoarthritis. Compared with men in the lowest (1st) quartile of 25(OH)D concentration, the HR for total hip replacement was 2.32 (95% CI 1.05, 5.13) for those in the 2nd quartile, 2.77 (95% CI 1.28, 6.00) for those in the 3rd quartile, and 1.73 (95% CI 0.75, 4.02) for those in the highest quartile of 25(OH)D concentrations (p for trend 0.02). There was little evidence of an association in women.

CONCLUSIONS

Higher circulating 25(OH)D concentrations were associated with an increased risk of total hip replacement for osteoarthritis in men but not in women. Although the underlying mechanism warrants further investigation, our findings highlight the need to determine the optimal levels of circulating 25(OH)D to reduce the risk of hip osteoarthritis.

Conundrum of vitamin D on glucose and fuel homeostasis

As an endocrine hormone, vitamin D plays an important role in bone health and calcium homeostasis. Over the past two decades, the non-calcemic effects of vitamin D were extensively examined. Although the effect of vitamin D on beta cell function were known for some time, the effect of vitamin D on glucose and fuel homeostasis has attracted new interest among researchers. Yet, to date, studies remain inconclusive and controversial, in part, due to a lack of understanding of the threshold effects of vitamin D. In this review, a critical examination of interventional trials of vitamin D in prevention of diabetes is provided. Like use of vitamin D for bone loss, the benefits of vitamin D supplementation in diabetes prevention were observed in vitamin D-deficient subjects with serum 25-hydroxyvitamin D < 50 nmol/L (20 ng/mL). The beneficial effect from vitamin D supplementation was not apparent in subjects with serum 25-hydroxyvitamin D > 75 nmol/L (30 ng/mL). Furthermore, no benefit was noted in subjects that achieved serum 25-hydroxyvitamin D > 100 nmol/L (40 ng/mL). Further studies are required to confirm these observations.

Vitamin D Trajectory after Total Knee Arthroplasty: A Method for Quick Correction in Deficient Patients

Backgroud

It has been widely reported that vitamin D (vit D) affects preoperative, postoperative, and long-term outcomes after total knee arthroplasty (TKA). Our aim was to study vit D trajectory after TKA and compare effects of oral versus intramuscular (IM) supplementation in insufficient patients and assess its effects on immediate functional recovery in the first 2 weeks after TKA.

Methods

Vit D levels < 30 ng/mL are considered insufficient. We prospectively enrolled 60 patients (20 per group): group I, vit D sufficient patients; group II, vit D insufficient patients given IM supplementation (cholecalciferol 6,00,000 IU); and group III, vit D insufficient patients given oral supplementation (cholecalciferol 600,000 IU). Vit D levels, knee flexion, Timed Up and Go (TUG) test results, and visual analog scale (VAS) score were recorded preoperatively and postoperatively on day 3 and 14.

Results

In group I, mean preoperative vit D significantly dropped at postoperative day (POD) 3 and POD 14 (p = 0.001). In group II, mean preoperative vit D rose at POD 3 and rose significantly at POD 14 (p = 0.001). In group III, mean preoperative vit D increased significantly at both POD 3 and POD 14 (p < 0.001). Also, in group III, the rise in vit D was significantly higher than that in group II both at POD 3 and POD 14 (p < 0.05). In group III, 19 of 20 insufficient patients became sufficient on POD 3 and all 20 by POD 14. In group II, even by POD 14, only 11 of 20 insufficient patients became sufficient. Functional parameters (flexion, change in flexion, TUG test results, and VAS score) were comparable (p > 0.05) in all groups. Changes in TUG test showed a significant increase in group II (48.5 seconds) when compared to group I (35.5 seconds) at POD 3 (p < 0.05), suggesting a slower recovery. It remained comparable (p > 0.05) between group III and group I.

Conclusions

We found that vit D insufficient patients can be rapidly supplemented on the morning of surgery with a large dose of oral cholecalciferol 600,000 IU, and the effect was consistent over 2 weeks after surgery. Orally supplemented vit D insufficient patients also showed functional recovery comparable to vit D sufficient patients. IM supplementation increased vit D levels only at 2 weeks and the rise was significantly lower than oral supplementation. Interestingly, approximately 25% of vit D sufficient patients who were not supplemented after TKA became insufficient in the first 2 weeks postoperatively.

Correlational analysis of bone health status and vitamin D-related biomarkers in women working in agriculture

The purpose of this study was to investigate the status of bone health in women working in agriculture and analyze the associations between bone health and various vitamin D-related biomarkers.This observational study enrolled women working in agriculture (n = 210) and control occupations (n = 180). The concentration of serum total 25-hydroxy vitamin D [25(OH)D] was measured using the Elecsys Vitamin D Total Kit, and serum vitamin D-binding protein (VDBP) was measured by enzyme-linked immunosorbent assay. Along with albumin, 25(OH)D and VDBP were used to calculate the concentrations of bioavailable and free 25(OH)D. Bone mineral density (BMD) and T-score were measured at lumbar 1 to 4 and the femur neck using dual-energy X-ray absorptiometry. To identify factors affecting BMD, log-linear model and linear regression analysis were performed for statistical analysis.Agricultural women workers showed higher serum concentrations of bioavailable 25(OH)D (12.8 ± 3.7 vs 8.7 ± 5.1 ng/mL) and lower VDBP concentrations (201.8 ± 45.0 vs 216.0 ± 68.2 μg/mL) than control women. The association between these 2 vitamin D related-biomarkers and femur neck BMD were confirmed through univariable and multivariable linear model analysis. Although lumbar BMD did not differ between groups, the agricultural group displayed a lower femur BMD and a 4.3-fold increase in the risk of osteoporosis compared with the control group.Women working in agriculture showed lower femur BMD than the control group. Of the vitamin D-related biomarkers tested, bioavailable 25(OH)D and VDBP were associated with BMD. As bioavailable 25(OH)D levels are affected mainly by VDBP levels, VDBP may play a role in the lower femur neck BMD values observed in the agricultural group. Thus, the measurement of VDBP concentration might be considered a simple and non-invasive method for measuring bone health status.

Association between vitamin D and glycaemic parameters in a multi-ethnic cohort of postmenopausal women with type 2 diabetes in Saudi Arabia

BACKGROUND

The relationship between vitamin D (VitD) and insulin sensitivity and secretion in type 2 diabetes mellitus (T2D) has been shown to be different amongst different ethnic populations. In Saudi Arabia, where both T2D and VitD deficiency are highly prevalent health concerns, little is known about the relationship between VitD, insulin sensitivity, resistance and the relative importance of ethnicity. Our primary aim in this study was to investigate influence of ethnicity on VitD association with glycaemic profile and to measures of obesity as a secondary outcome, among multiethnic postmenopausal women with T2D in Saudi Arabia.

METHODS

A cross-sectional study was conducted at King Fahad Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia. Postmenopausal females (n = 173, age ≥ 50 years) with T2D were randomly selected in this study. Anthropometric measures and fasting blood samples were obtained for all study participants. Several biochemical parameters were measured including 25-hydroxyvitamin D (25(OH)D), glycosylated hemoglobin (HbA1c), insulin, glucose and c-peptide. Surrogate markers for insulin resistance were calculated using Homeostasis Model Assessment 2 for insulin resistance and beta cell activity (HOMA2-IR, HOMA2-β).

RESULTS

Overall, 25(OH)D was inversely associated with fasting glucose (r=-0.165, P = 0.037), insulin (r=-0.184, P = 0.02), C-peptide (r=-0.19, P = 0.015) and HOMA2- IR C-peptide (r=-0.23, P = 0.004). Additionally, serum 25 (OH)D showed a negative correlation with body weight (r=-0.173 P = 0.028), waist and hip circumferences (r=-0.167, P = 0.033; r=-0.22, P = 0.004 respectively) but not with body mass index (BMI) or waist hip ratio (WHR). In the white ethnic group but not in black or Asian population groups, 25(OH)D level was also associated with only serum fasting C-peptide and HOMA2-IR C-peptide and BMI (P < 0.05).

CONCLUSIONS

Insulin resistance and obesity were associated with VitD status in T2D in this cohort. Our findings also suggest that these VitD associations in women from white ethnic background are different than in those from black/Asian ethnic backgrounds. Whether VitD supplements are able to improve either obesity and/or insulin sensitivity should be further investigated in different ethnic population groups.

Comparative analysis of the association between various serum vitamin D biomarkers and sarcopenia

Background

Vitamin D status is associated with muscle strength and maintenance of muscle fibers. However, which serum vitamin D biomarker better reflects sarcopenia remains unclear. The aim of this study was to investigate associations between various serum vitamin D biomarkers (total 25‐hydroxy vitamin D [25(OH)D], bioavailable 25(OH)D, 24,25‐dihydroxyvitamin D [24,25(OH)₂D], and vitamin D metabolite ratio [VMR]) and sarcopenia.

Methods

The data for 83 hip fracture patients were finally included in the analysis. Sarcopenia was defined according to the Asia Working Group for Sarcopenia (AWGS) criteria. Measurements of 24,25(OH)₂D and 25(OH)D were made using solid‐phase extraction (SPE) and subsequent liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). Vitamin D binding protein (VDBP) concentration was measured using an enzyme‐linked immunosorbent assay. The VMR was calculated by dividing serum 24,25(OH)₂D by serum 25(OH)D and then multiplying by 100. Based on total 25(OH)D, VDBP, and albumin concentrations, bioavailable 25(OH)D concentrations were calculated using the equations from the other previous studies.

Results

Bioavailable 25(OH)D levels were significantly (p = 0.030) decreased in the sarcopenia group compared with the non‐sarcopenia group. Results of ROC analysis for the diagnosis of sarcopenia using serum level of bioavailable of 25(OH)D revealed that the cutoff point for bioavailable 25(OH)D was 1.70 ng/ml (AUC = 0.649, p < 0.001). In the group with a bioavailable 25(OH)D less than 1.70 ng/ml, the incidence of sarcopenia increased by 3.3 times (odds ratio: 3.33, p = 0.013).

Conclusion

We demonstrated that bioavailable 25(OH)D was associated with sarcopenia among the various serum vitamin D biomarkers. Bioavailable vitamin D might be helpful for assessing the risk of sarcopenia.

Safety and efficacy of common vitamin D supplementation in primary hyperparathyroidism and coexistent vitamin D deficiency and insufficiency: a systematic review and meta-analysis

PURPOSE

Primary hyperparathyroidism (PHPT) is characterized by excessive secretion of parathyroid hormone (PTH). Vitamin D deficiency can stimulate parathyroid secretion. However, whether to correct vitamin D deficiency in patients with PHPT is controversial. We aimed to evaluate the safety and efficacy of vitamin D replacement in patients with PHPT.

METHODS

We searched PubMed, Cochrane Library, and Embase. The relevant data were extracted from the included documents. The methodological items for non-randomized studies score entries were used for evaluation of quality. Review Manager 5.3 and Stata 12.0 were used for statistical analysis.

RESULTS

A total of 11 articles were included with a total of 388 patients. The serum calcium mean difference (MD) was - 0.06 mg/dL [95% confidence interval (95% CI) - 0.16, 0.04]. Subgroup analysis showed that serum calcium levels did not change if the intervention time exceeded 1 month. The 24-h urinary calcium MD was 36.78 mg/day (95% CI - 37.15, 110.71), which indicated that there was no significant effect of vitamin D supplementation on 24-h urinary calcium levels. The MD of PTH was - 16.01 pg/mL (95% CI - 28.79, - 3.24). Subgroup analysis according to the intervention time showed that vitamin D intervention for more than 1 month significantly reduced PTH levels. The ALP MD was - 10.81 U/L (95% CI - 13.98, - 7.63), which indicated Vitamin D supplementation reduced its level. The MD of 25-hydroxyvitamin D was 22.09 μg/L (95% CI 15.01, 29.17), and no source of heterogeneity was found.

CONCLUSION

Vitamin D supplementation in patients with PHPT and vitamin D deficiency significantly reduces PTH and ALP levels without causing hypercalcemia and hypercalciuria.

Effect of Summer Sunshine Exposure on Vitamin D Status in Young and Middle Age Poles: Is 30 ng/mL Vitamin D Cut-Off Really Suitable for the Polish Population?

Background: There is no consensus regarding vitamin sufficiency status with either 20 ng/mL or 30 ng/mL sufficiency cut-off. We assessed the effects of summer sunshine exposure on vitamin D status. Participants: We measured vitamin D concentrations, PTH, creatinine, and total calcium in 132 healthy subjects, age 29.36 ± 13.57 years, in spring and autumn. Results: There was an overall increase in vitamin D concentrations from spring to autumn from 18.1 ± 7.39 ng/mL to 24.58 ± 7.72 ng/mL, (p < 0.001), accompanied by a decrease in PTH from 44.4 ± 17.76 pg/mL to 36.6 ± 14.84 pg/mL, (p < 0.001). In spring, only 5.3% of individuals were vitamin D sufficient for a 30 ng/mL cut-off, increasing to 23.2% in autumn (p < 0.001). In contrast, when a 20 ng/mL cut-off was employed, vitamin D sufficiency was found in 34.1% in spring and 66.4% individuals in autumn, respectively, (p < 0.001). In multiple regression analysis, holiday leave was the only significant determinant of vitamin D increase (p < 0.001). Conclusions: Holiday leave is the strongest determinant of an increase in vitamin D. The majority of healthy individuals fail to reach a 30 ng/mL vitamin D cut-off after summer sunshine exposure. This raises the question, whether such a cut-off is indeed suitable for the Polish population.

Development and Validation of a Predictive Model of Hypovitaminosis D in General Adult Population: SCOPYD Study

The worldwide global increase in serum 25-hydroxyvitamin D (25(OH)D) measurements has led some countries to restrict reimbursement for certain clinical situations only. Another approach could consist in providing physicians with screening tools in order to better target blood test prescription. The objective of the SCOPYD study was to identify the best combination of predictors of serum VitD concentration among adults aged 18–70 years. Potential risk factors for VitD deficiency were collected using a comprehensive self-administered questionnaire. A multivariable linear regression was used to build a predictive model of serum 25(OH)D concentration. Among 2488 participants, 1080 (43.4%) had VitD deficiency (<50 nmol/L) and 195 (7.8%) had severe deficiency (<25 nmol/L). The final model included sunlight exposure in the preceding week and during the last holidays, month of blood sampling, age, sex, body mass index, skin phototype, employment, smoking, sport practice, latitude, and VitD supplementation in preceding year. The area under the curve was 0.82 (95% CI (0.78; 0.85)) for severe deficiency. The model predicted severe deficiency with a sensitivity of 77.9% (95% CI (69.1; 85.7)) and a specificity of 68.3% (95% CI (64.8; 71.9)). We identified a set of predictors of severe VitD deficiency that are easy to collect in routine that may help to better target patients for serum 25(OH)D concentration determination.

High-dose vitamin D3 supplementation ameliorates renal fibrosis by vitamin D receptor activation and inhibiting TGF-β1/Smad3 signaling pathway in 5/6 nephrectomized rats

Renal fibrosis is the pathological consequence of progressive chronic kidney disease. Although it has been reported that vitamin D3 exerts antifibrotic effects, the underlying mechanisms remain unclear. This study is aimed at investigating the effects and molecular mechanisms in high-dose vitamin D3 treatment on renal fibrosis. A model of chronic kidney disease was established by 5/6 nephrectomy in rats characterised by high levels of serum creatine, urea nitrogen, and urinary protein. Serum 25-dihydroxyvitamin D3, calcium and parathormone levels were measured to evaluate vitamin D levels. Hematoxylin and eosin, periodic acid Schiff and Mallory's Trichrome staining were used to evaluate histopathological changes in rats. Moreover, the expression of vimentin, collagen I, α-smooth muscle actin and E-cadherin were analyzed at molecular and histopathological levels. Our results showed that exposure to vitamin D3 decreased the levels of serum creatine, urea nitrogen and urine protein and restored the homeostasis of calcium and parathormone. Vitamin D3 also downregulated the expression of vimentin, collagen I and α-smooth muscle actin and attenuated renal fibrosis and epithelial to mesenchymal transition in the kidney. Importantly, vitamin D3 treatment increased the expression of the vitamin D receptor and inhibited Transforming growth factor-β1 (TGF-β1)/Smad3 signaling pathway in rats kidneys with chronic kidney disease. Mechanistically, the upregulation of TGF-β1 and phosphorylation of Smad3 induced by vitamin D3 was reversed by activation of the vitamin D receptor. Our findings indicated that vitamin D3 is a potential antifibrotic drug in chronic kidney disease via the vitmin D receptor and inhibiting TGF-β1/Smad3 signaling pathway.

A rare case of low voltage electrical injury leading to bilateral femur fractures and vertebral body fractures: A case report and review of the literature

Introduction and importance

Low voltage electrical injuries (less than 1000 V) can produce enough tetany to cause fractures, usually of the upper extremities. Simultaneous bilateral fractures of the femoral neck are an extremely rare occurrence. It is even more uncommon for a young healthy male to suffer significant fractures from a low voltage injury.

Case presentation

A 25-year-old male attempted suicide by filling a bathtub with water and getting into it prior to dropping a blender into the water. He experienced full body convulsions but remained awake throughout the entire event. In the trauma bay his primary complaints were bilateral hip pain and back pain, without neurologic deficit. Radiological studies confirmed bilateral sub-capital femur fractures and thoracic vertebral fractures (compression fractures of T3, T4, T5, T6, T7, T9, and T11). The patient underwent bilateral open reduction and internal fixation (ORIF) of the femurs, while the spine fractures were treated with a thoracic-lumbar-sacral orthosis TLSO brace.

Clinical discussion

Low voltage electrical injury is more likely to lead to fractures in patients with chronic renal failure and metabolic conditions such as hypocalcemia, osetomalacia, and osteoporosis. Fractures after low voltage electrical injury are extremely uncommon and a high suspicion for these injuries should be maintained because if missed there is a high risk of morbidity and mortality.

Conclusion

We present a rare case of low voltage electrical injury by 120 V from a domestic US power supply, amplified by water conduction resulting in bilateral femoral neck fractures and vertebral body fractures.

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Fractures resulting from low voltage electrical injury are usually related to chronic renal failure, and metabolic conditions such as hypocalcemia, osetomalacia, and osteoporosis.

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Electrical injuries require a thorough assessment including voltage, duration of injury, environment (wet skin or humid environment), and any existing comorbidities.

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Bilateral femure and vertebral fractures are rare injuries following low-voltage electrical injury.

Nutritional rickets & osteomalacia: A practical approach to management

Defective mineralization of the growth plate and preformed osteoid result in rickets and osteomalacia, respectively. The leading cause of rickets worldwide is solar vitamin D deficiency and/or dietary calcium deficiency collectively termed as nutritional rickets. Vitamin D deficiency predominates in high-latitude countries in at-risk groups (dark skin, reduced sun exposure, infants and pregnant and lactating women) but is emerging in some tropical countries due to sun avoidance behaviour. Calcium deficiency predominates in tropical countries, especially in the malnourished population. Nutritional rickets can have devastating health consequences beyond bony deformities (swollen wrist and ankle joints, rachitic rosary, soft skull, stunting and bowing) and include life-threatening hypocalcaemic complications of seizures and, in infancy, heart failure due to dilated cardiomyopathy. In children, diagnosis of rickets (always associated with osteomalacia) is confirmed on radiographs (cupping and flaring of metaphyses) and should be suspected in high risk individuals with the above clinical manifestations in the presence of abnormal blood biochemistry (high alkaline phosphatase and parathyroid hormone, low 25-hydroxyvitamin D and calcium and/or low phosphate). In adults or adolescents with closed growth plates, osteomalacia presents with non-specific symptoms (fatigue, malaise and muscle weakness) and abnormal blood biochemistry, but only in extreme cases, it is associated with radiographic findings of Looser's zone fractures. Bone biopsies could confirm osteomalacia at earlier disease stages, for definitive diagnosis. Treatment includes high-dose cholecalciferol or ergocalciferol daily for a minimum of 12 wk or stoss therapy in exceptional circumstances, each followed by lifelong maintenance supplementation. In addition, adequate calcium intake through diet or supplementation should be ensured. Preventative approaches should be tailored to the population needs and incorporate multiple strategies including targeted vitamin D supplementation of at-risk groups and food fortification with vitamin D and/or calcium. Economically, food fortification is certainly the most cost-effective way forward.

Comparison of vitamin D levels between patients with pterygium and healthy subjects

PURPOSE

The purpose of this study was to compare vitamin D (VD) deficiency frequency among patients with pterygium to that of healthy subjects and to investigate the VD deficiency among patients with pterygium.

METHODS

One-hundred eight pterygium patients and 94 healthy subjects were included in the study. Blood samples were collected from groups during the same time interval and the samples were saved. Serum 25-hydroxyvitamin D (25(OH)D) and parathormone (PTH) levels were measured and analyzed.

RESULTS

The pterygium group consisted of 57 female and 51 male patients, while the control group consisted of 47 female and 47 male patients. The mean age, sex and mean BMI were similar in the two groups (p > 0.05). The percentage of time that individuals spent outdoors was higher in the pterygium group (p = 0.02). The percentage of VD deficiency was 83.3% in the pterygium group and 61.7% in the control group (p = 0.001). There was a positive correlation between VD and time spent outdoors (p < 0.05).

CONCLUSIONS

VD deficiency can play a role in pterygium etiopathogenesis. Wide population-based studies in different regions are needed to evaluate this result.

Vitamin D Status in Spanish Elite Team Sport Players

Low vitamin D is usual; however, data are limited for elite team players. The aim was to investigate the vitamin D levels in Football Club Barcelona (FCB) first division players of six sport modalities. Ninety-five elite male players (27.3 ± 4.6 y) belonging to FCB provided data for vitamin D throughout a season. In this study, 25(OH)D was measured in serum by chemiluminescent immunoassay. Outdoor/indoor training and supplementation were also considered. Total mean 25(OH)D concentrations were 91.9 ± 23.1 nmol/L in all players, with higher mean levels among supplemented players (94.7 ± 24.3 nmol/L). Around 25% of the team players were below optimal levels (<75 nmol/L), but none were below 50 nmol/L. Caucasian, supplemented football and handball players had the highest mean vitamin D concentrations over the whole year, whereas basketball players (indoor training) had the lowest ones. The highest rate of vitamin D insufficiency was found in spring (40%). A positive significant effect was observed for the interaction between indoor/outdoor training and supplementation with 25(OH)D concentrations (p < 0.05). Those team players training outdoors with supplementation had higher total vitamin D concentrations than those with indoors training and/or supplementation. A positive interaction of outdoor training with supplementation exists to determine 25(OH)D concentrations in team players.

Efficacy of Weekly Split versus Single Doses of Ergocalciferol on Serum 25-Hydroxyvitamin D among Patients on Continuous Ambulatory Peritoneal Dialysis: A Randomized Controlled Trial

Background

Vitamin D deficiency is a common problem among patients on continuous ambulatory peritoneal dialysis (CAPD). Vitamin D supplementation leads to reduced serum parathyroid hormone levels and improved cardiovascular markers. Different doses and time intervals of oral vitamin D supplementation may differ in each patient on dialysis. The study aimed to evaluate the efficacy of weekly split and single dose of ergocalciferol at 60,000 IU on serum 25-hydroxyvitamin D (25(OH)D) among patients on CAPD.

Methods

A randomized study was conducted among patients on CAPD with vitamin D deficiency or insufficiency (25(OH)D < 30 ng/mL). Patients were randomly assigned to two groups: the split dose group was given ergocalciferol 20,000 IU three times weekly and the single dose group was given ergocalciferol 60,000 IU once weekly for 8 weeks. Main outcomes measured serum 25(OH)D concentrations, serum calcium, serum phosphate, and intact parathyroid levels at 8 weeks after being enrolled.

Results

Of 128 screened patients, 50 met the criteria for eligibility and were randomized. At 8 weeks after treatment, mean serum 25(OH)D concentrations significantly increased from baseline 22.7 ± 5.9 to 29.5 ± 9.5 ng/mL (P=0.004) in the split dose group and 22.9 ± 5.3 to 31.2 ± 12.3 ng/mL (P=0.003) in the single dose group. No significant change was found in increase of serum 25(OH)D between the two groups (P=0.561). At the end of study, a similar proportion of patients in both groups reached the desirable serum concentration of 25(OH)D ≥ 30 ng/mL (60% in the single group vs. 40% in the split group, P=0.258). No significant cases of hypercalcemia, hyperphosphatemia, or serious adverse events occurred during the study.

Conclusion

Weekly single and split doses of ergocalciferol 60,000 IU achieved similar effects on serum 25(OH)D levels among patients on CAPD with vitamin D insufficiency or deficiency, suggesting that weekly single dose would be prescribed for adequate vitamin D repletion. This trial is registered with TCTR20200821005.

Vitamin D and Its Potential Benefit for the COVID-19 Pandemic

Vitamin D is known not only for its importance for bone health but also for its biologic activities on many other organ systems. This is due to the presence of the vitamin D receptor in various types of cells and tissues, including the skin, skeletal muscle, adipose tissue, endocrine pancreas, immune cells, and blood vessels. Experimental studies have shown that vitamin D exerts several actions that are thought to be protective against coronavirus disease (COVID-19) infectivity and severity. These include the immunomodulatory effects on the innate and adaptive immune systems, the regulatory effects on the renin-angiotensin-aldosterone-system in the kidneys and the lungs, and the protective effects against endothelial dysfunction and thrombosis. Prior to the COVID-19 pandemic, studies have shown that vitamin D supplementation is beneficial in protecting against risk of acquiring acute respiratory viral infection and may improve outcomes in sepsis and critically ill patients. There are a growing number of data connecting COVID-19 infectivity and severity with vitamin D status, suggesting a potential benefit of vitamin D supplementation for primary prevention or as an adjunctive treatment of COVID-19. Although the results from most ongoing randomized clinical trials aiming to prove the benefit of vitamin D supplementation for these purposes are still pending, there is no downside to increasing vitamin D intake and having sensible sunlight exposure to maintain serum 25-hydroxyvitamin D at a level of least 30 ng/mL (75 nmol/L) and preferably 40 to 60 ng/mL (100-150 nmol/L) to minimize the risk of COVID-19 infection and its severity.

Seasonal Changes in Vitamin D Levels of Healthy Children in Mid-Latitude, Asian Urban Area

PURPOSE

This study aimed to investigate the seasonal changes in vitamin D levels in a healthy pediatric population living in mid-latitude East Asian urban areas.

METHODS

A pediatric population was selected from single secondary hospital visitors. Clinical data and serum vitamin D levels were collected retrospectively. Statistical analyses were performed based on the month of the blood sampling date, subject age, and vitamin D supplementation history. The data were categorized into three subgroups based on serum vitamin D levels-adequate (≥30 ng/mL), insufficient (20-29 ng/mL), and deficient (<20 ng/mL).

RESULTS

Of the 481 patients, 172 had vitamin D supplementation history. More than 70% of the total study population had inadequate vitamin D levels (<30 ng/mL). The non-supplemented group and the supplemented group showed significantly uneven monthly distribution of the adequate, insufficient, and deficient subgroups. Only the non-supplemented group showed significantly different average vitamin D levels in the summer months compared to the winter months. In the non-supplemented group, vitamin D levels were the lowest in March, the highest in August and September. Significant relevance was noted between vitamin D supplementation status and vitamin D serum level in February and March. There was no significant difference between different age groups in terms of the distribution of vitamin D levels.

CONCLUSION

Currently-widespread vitamin D replacement methods seem to have some effect on increasing the overall serum vitamin D levels, specifically during late winter when natural serum vitamin D levels plunge. However, they are unable to fully compensate the seasonal fluctuation.

Non-Musculoskeletal Benefits of Vitamin D beyond the Musculoskeletal System

Vitamin D, a fat-soluble prohormone, is endogenously synthesized in response to sunlight or taken from dietary supplements. Since vitamin D receptors are present in most tissues and cells in the body, the mounting understanding of the role of vitamin D in humans indicates that it does not only play an important role in the musculoskeletal system, but has beneficial effects elsewhere as well. This review summarizes the metabolism of vitamin D, the research regarding the possible risk factors leading to vitamin D deficiency, and the relationships between vitamin D deficiency and numerous illnesses, including rickets, osteoporosis and osteomalacia, muscle weakness and falls, autoimmune disorders, infectious diseases, cardiovascular diseases (CVDs), cancers, and neurological disorders. The system-wide effects of vitamin D and the mechanisms of the diseases are also discussed. Although accumulating evidence supports associations of vitamin D deficiency with physical and mental disorders and beneficial effects of vitamin D with health maintenance and disease prevention, there continue to be controversies over the beneficial effects of vitamin D. Thus, more well-designed and statistically powered trials are required to enable the assessment of vitamin D’s role in optimizing health and preventing disease.

Serum 24,25-dihydroxyvitamin D level in general Korean population and its relationship with other vitamin D biomarkers

Background

Vitamin D status is presently assessed by measuring total serum concentration of 25-hydroxyvitamin D [25(OH)D]. However, 25(OH)D concentration alone might not accurately reflect vitamin D status owing to its weak relationship with various clinical indices and inconsistency across races. Recently, 24,25-dihydroxyvitamin D [24,25(OH)₂D] and vitamin D metabolite ratio [VMR; ratio of 24,25(OH)₂D to 25(OH)D] have emerged as vitamin D biomarkers. The present study aimed to determine the values of 24,25(OH)₂D and VMR in healthy Koreans and compare them with other vitamin D biomarkers, including 25(OH)D and bioavailable 25(OH)D.

Methods

Serum samples and medical information were collected from 200 individuals (100 females and 100 males) who underwent general health checks without self-reported symptoms. We measured 24,25(OH)₂D concentration using liquid chromatography–tandem mass spectrometry, and concentrations of 25(OH)D and vitamin D binding protein using immunoassays. VMR and bioavailable 25(OH)D concentration were calculated using the above data. Serum parathyroid hormone level, and bone mineral density (BMD) data were collected as clinical outcomes, and the effects of the vitamin D markers on them were tested using multiple linear regression models.

Results

The mean values of 25(OH)D, 24,25(OH)₂D, VMR, and bioavailable 25(OH)D were 24.3 ± 8.5 ng/mL, 1.9 ± 1.1 ng/mL, 7.6 ± 2.5, and 3.2 ± 1.2 ng/mL, respectively. The concentration of 25(OH)D closely correlated with 24,25(OH)₂D (R = 0.868, P < 0.001) and bioavailable 25(OH)D (R = 0.862, P < 0.001). No significant effects of 24,25(OH)₂D, VMR, and bioavailable 25(OH)D were observed on the prediction of PTH and BMD in the multiple linear regression models.

Conclusion

Our study presents the distribution of 24,25(OH)₂D concentration and VMR in Korean population for the first time. Overall, our data reaffirm that 25(OH)D is the primary marker for determining vitamin D status in the general population.