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Background: Diabetes mellitus (DM) has affected over 387 million patients globally, expected to reach 592 million by the end of 2035. It is a metabolic disorder characterized by chronic hyperglycemia caused by either insulin deficiency, insulin resistance, or both., Materials and Methods: The present study was designed to estimate the levels of different bone markers; serum Vitamin D, alkaline phosphatase, phosphorus, and calcium in patients with type 2 DM (T2DM). The study was conducted on patients aged 20-50 years diagnosed with T2DM, who were attending the outpatient/inpatient department of internal medicine., Results: The levels of calcium were decreased in the patients with diabetes and also the study proved a negative correlation between calcium and random plasma glucose (RPG). There was a significant negative correlation between RPG and serum 25(OH)D3., Conclusion: We conclude that Vitamin D insufficiency is frequent in Moradabad, Uttar Pradesh. Sunshine exposure daily for 15 min on the face and hands is necessary to elevate the sunlight Vitamin D levels., (Copyright © 2024 Copyright: © 2024 Annals of African Medicine.)

Vitamin D deficiency is a global health burden, which has been subject to debate in recent years. Although its consequences on patients' general health are debatable, the association between severe vitamin D deficiency and osteomalacia are clearly established. Since the 1st of July 2022, blood testing in individuals who do not meet the recognized risk factors for deficiency is no longer reimbursed in Switzerland. Being a migrant (or refugee) does not constitute a risk factor even though it has repeated been shown that this population is at high risk of deficiency, in particular sever deficiency. This article aims to establish new recommendations for vitamin D deficiency diagnosis and substitution for this population. It is sometimes necessary to adapt our national recommendations to take into account our cultural diversity., Competing Interests: Les auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Vitamin D deficiency is so frequent in older patients (aged 65 years and older) that the international consensus does not recommend routine vitamin D measurement. Assessment of overall health status is a cornerstone before considering vitamin D supplementation, as the effect of vitamin D supplementation has only been demonstrated in vulnerable or dependent but not for robust older patients. The effect of the different modalities of oral vitamin D supplementation are equivalent : 800-1'200 IU/day, 10'000 IU/week or 30'000-50'000 IU/month. Monitoring of vitamin D blood level monitoring is not necessary because of a large therapeutic margin. In the presence of osteoporosis, a dietary or supplementation intake of 1'200 mg per day of calcium should be added., Competing Interests: Les auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Vitamin D deficiency affects more than half of the general population. During pregnancy vitamin D insufficiency is associated with a higher risk of complications such as an increased incidence of miscarriages. Preterm delivery, preeclampsia, gestational diabetes, growth retardation and low birth weight as well as postpartum hemorrhage are all pathologies whose incidence seems to be increased with hypovitaminosis D. This could be linked to the pregnancy changes of the immune system, on which vitamin D plays a well-known modulating role. Substitution, even if its benefit is not clearly established, should be considered as there are no side effects. Although lack of evidence regarding the timing of the introduction of treatment, substitution may be proposed before conception., Competing Interests: Les auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Vitamin D deficiencies are common throughout the world. In Switzerland, this deficiency affects every populations, including therefore people at risk of COVID-19 complications. Several studies demonstrate a correlation between vitamin D deficiencies and some chronic extraosseous pathologies. This literature review shows a correlation between the seriousness of symptoms, the deaths related to COVID-19 and a status of vitamin D deficiency. The effectiveness of a supplementation with vitamin D to improve those pathologies and limit complications due to COVID-19 is not yet clear because of the various methodological bias of the studies. However, the epidemiological extent of a vitamin D deficiency in our societies requires the coordinated actions of all health professionals in order to meet this public health challenge., Competing Interests: Les auteures n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Competing Interests: "Tous les auteurs répondent à tous les critères suivants : contribution à la conception ou à l’analyse et à l’interprétation des données ; rédaction de l’article ou révision critique et apport intellectuel important ; approbation de la version finale à publier."

Competing Interests: É. Cavalier déclare avoir des liens durables avec les entreprises IDS, DiaSorin, Fujirebio, Nittobo, BioMérieux, Menarini et Volition.

Introduction: Vitamin D deficiency is widespread throughout the world. Vitamin D has an important role in the regulation of phosphocalcic metabolism as well as in a large number of biological and metabolic processes. According to some studies, there is a correlation between vitamin D and LDL-cholesterol levels. A deficiency of vitamin D and / or a high level of LDL-cholesterol could represent risk factors for bone healing and osteointegration of dental implants. The purpose of our study is to demonstrate the reality of the problem of deficiency or deprivation in vitamin D in a population of patients requiring oral and / or implant surgery., Material and Methods: 46 cases of patients having undergone oral surgery together with preoperative blood test were analyzed. The results of the dosages of 25-hydroxy-vitamin D (25-OH-D), total cholesterol, LDL-cholesterol, HDL-cholesterol were collected and compared with reference values. Statistical tests were performed to determine the possible correlations between the 25-OH-D level and other blood parameters., Results: 38 patients out of 46 (82.6 %) are defective in vitamin D, and 7 patients out of 46 (15.2 %) are deficient. LDL-cholesterol levels were high in 15 patients out of 33 (45.5 %). There was a non-significant correlation between LDLcholesterol and vitamin D levels. Total cholesterol was high in 42 % of patients. We observed a significant correlation between total cholesterol and vitamin D levels., Conclusion: According to our study, it appears that a preoperative assessment including the dosage of vitamin D, total cholesterol and LDLcholesterol may be of interest in patients requiring oral and / or implant surgery by correcting if necessary blood parameters and promoting bone metabolism.

Introduction: Screening and treatment of vitamin D deficiency are the subject of several publications. A lot of recognized risk factors have increased steadily, leading to the recognition of populations at risk. Despite their exposure to the same risk factors as other populations, there are no recommendations concerning healthy adults, a population rarely studied. To determine the prevalence of vitamin D deficiency in healthy adults aged 18-65 years residing in northern France and to search for correlated risk factors at 20ng/mL., Methods: Descriptive, prospective, single-center epidemiology study; 297 subjects studied in January and February, 2015. The prevalence of vitamin D deficiency was determined at three serum levels (10, 20 and 30ng/mL). A self-administered questionnaire was used to identify risk factors correlated with vitamin D deficiency (<20ng/mL)., Results: 25(OH) vitamin D serum level was strictly less than 30ng/mL in 92.3% of participants, strictly less than 20ng/mL in 75.1%, and strictly less than 10ng/mL in 27.9%. Male gender (P=0.0001), age (P=0.012), no vacations in sunny regions (P=0.03) and no intake of prescription vitamin supplements (P=0.002) were independent risk factors of vitamin D deficiency (<20ng/mL)., Conclusion: In our population, vitamin D deficiency is frequent in healthy adults and is often severe. A systematic screening and supplementation strategy would limit the development of many pathological complications and ensure good nutritional balance., (Copyright © 2016 Société Nationale Française de Médecine Interne (SNFMI). Published by Elsevier SAS. All rights reserved.)

Introduction: 25 (OH) vitamin D plays an important role in many places through the body. Its deficien- cy can cause rickets or osteomalacia. This is particularly im- portant in hemodialysis (HD) patients who are at icreased risk due to decreased sunlight exposure and deterioration of their mineral homeostasis., Objectives: To determine the prevalence of 25 (OH) vitamin D deficiency in HD patients at Rafic Hariri University Hospital (RHUH), compared to a sample of the general population matched for gender and age, and to evaluate the effectiveness of 25 (OH) vitamin D supplementation in HD deficient group., Methods: This is a cross sectional study conducted since December 2012, comparing the prevalence of 25 (OH) vitamin D deficiency in HD patients in the dialysis center at RHUH, with patients from the general population who sought medical attention at RHUH for purposes other than HD, matched for age and gender. 25 (OH) vitamin D levels were measured with radio- immunoassay method (LOINC) at CIC European Lab, Bar- celona, Spain. A pilot study was conducted with the 34 HD patients who turned out to be deficient or insufficient in 25 (OH) vitamin D. We supplemented them with cholecalciferol over 6 months. We then assessed their vitamin D levels, and biochemistry parameters., Results: The prevalence of 25 (OH) vitamin D deficiency in the sample of HD patients at baseline was 32% while that of insufficiency was 36%. The prevalence of 25 (OH) vitamin D deficiency in the sample of general population was 67%. No correlation was found be- tween 25 (OH) vitamin D levels and the studied parameters. In the pilot study, after six months of cholecalciferol supple- mentation, there was a significant improvement in 25 (OH) vitamin D levels in the deficient and insufficient groups., Conclusion: The sample studied in the general population showed high prevalence of 25 (OH) vitamin D deficiency (67%). The sample studied in HD patients showed a preva- lence of 25 (OH) vitamin D deficiency of 32% and insuffi- ciency of 36%. The pilot study showed that 25 (OH) vitamin D supplementation in the form of cholecalciferol is beneficial in HD patients.

The 25-hydroxyvitamin D (25OHD) serum concentration is the consensual marker of vitamin D status. In the general population, the Institute of Medicine considers that a 25OHD level >20 ng/mL is sufficient for bone health in most subjects. In osteoporosis patients, in those who have a pathology or who receive drugs that may increase the risk of osteoporosis, as well as in patients with chronic kidney disease, many experts think that an optimal vitamin D status is better defined by a 25OHD concentration >30 ng/mL. In the French general population, 43-50% of subjects have a 25OHD level <20 ng/mL and approximately 80% have a 25OHD <30 ng/mL. In chronic diseased patients, as well as in some categories of the general population such as elderly people, the percentage of subjects with a 25OHD level below 20 ng/mL is frequently well above 50%. Epidemiologic studies allow us to identify risk factors for vitamin D deficiency such as ageing, overweight, dark skin pigmentation, wearing covering clothes, or having a low level of outdoor activity. This will help to target vitamin D supplementation to "at-risk" subjects. However, discussions on means to improve the vitamin D status of the overall population such as allowing higher levels of food fortification, are needed.

Unlabelled: French guidelines do not recommend systematic supplementation of vitamin D in children aged 5-10 years old owing to the lack of data on vitamin D status in this age group. Our objective was to assess the prevalence of vitamin D deficiency in these children., Methodology: Single-center, prospective, epidemiological study including 358 children aged 0-15 years. The endpoint was the concentration of vitamin D., Results: In all, 316 children were divided into four groups according to age: 0-18 months (n=113); 18 months to 5 years (n=103); 5-10 years (n=62); and 10-15 years (n=38). The median concentration of vitamin D decreased with age (P<0.001): 90.2 nmol/L in the group aged 0-18 months; 56.7 nmol/L in the group aged 18 months to 5 years; 49.05 nmol/L in the group aged 5-10 years; and 42.45 nmol/L in the group aged 10-15 years. This corresponds to an increase in the prevalence of vitamin D deficiency in children aged 5-10 years (51.6% vs. 8.8% in the group aged 0-18 months, P<0.001). For children aged 5-10 years, the prevalence of deficiency was greater in the non-supplementation group (75%) compared with the supplementation group (13%; P<0.001)., Conclusion: This study demonstrates the high prevalence of vitamin D deficiency in children aged 5-10 years and the relationship between supplementation and vitamin D status. It provides an argument in favor of supplementation in children aged 5-10 years in this region and a reconsideration of the French recommendations., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

Objective: To assess the vitamin D status of children aged 6-10years in the French general population for whom no guidelines have yet been defined due to insufficient data., Method: The study was conducted during two winters with very different sunshine levels: 5 March to 17 April 2012 and 8 January to 16 April 2013 in 20 then 22 centers. Three hundred children (60 children for each year of age) attending an ambulatory care unit or outpatient department for a reason unrelated to vitamin D status were included at the end of winter in 20 hospital centers (ten centers in the northern half of France above latitude 46-47°N/Lille: 50°N and ten centers in the southern half of France below latitude 46-47°N/Marseille: 43°N). Centralized 25 hydroxyvitamin D (25(OH)D), alkaline phosphatase (ALP), and parathormone (PTH) assays were performed on leftover blood samples. The currently accepted normal range for 25(OH)D was used to define the following categories: ≤25nmol/L: severe vitamin D deficiency, 25nmol/L100nmol/L: high vitamin D status. A standardized questionnaire was used to collect the child's characteristics, use of a vitamin D supplement, and milk and dairy product intake. The cumulative number of hours of sunshine over the 90days prior to inclusion in each center was obtained from the Météo-France weather bureau., Results: 25(OH)D assays were performed in 326 children; more than 95% of children received milk and dairy products and 38% had received a vitamin D supplement since starting the school year: 3.1% of children in the overall population presented severe vitamin D deficiency, 34.4% presented vitamin D deficiency, 53.1% had a sufficient vitamin D status, and 9.5% had a 25(OH)D concentration >100nmol/L with no impact on serum calcium and urinary calcium. Children living in the north of France generally had lower 25(OH)D levels than children living in the south of France. In the non-supplemented population (n=188), 5.3% of children presented severe vitamin D deficiency, 45.2% presented vitamin D deficiency and 48.4% had sufficient 25(OH)D levels. The percentage of children with severe vitamin D deficiency or vitamin D deficiency was twofold higher during the winter with poor sunshine compared to the sunnier winter with a less marked north/south difference. No case of severe vitamin D deficiency was observed in the supplemented population (n=119); 10-15% of children presented vitamin D deficiency and 22.7% had a 25(OH)D concentration >100nmol/L, while remaining within the acceptable range. Two cases of hypervitaminosis without hypercalcemia were identified: one after an unknown loading dose with a calcium/creatinine ratio in the normal range (0.8); for the second one, no additional information could be obtained. Vitamin D supplementation considerably reduced the north/south difference and the Winter1/Winter2 difference. A child not receiving a vitamin D supplement had a ninefold higher risk of vitamin D deficiency at the end of winter than a child receiving a vitamin D supplement (OR=8.8; 95%CI, 4.6-16.8)., Conclusion: At least one-third of children aged 6-10years presented deficient 25(OH)D levels. None of the children receiving a vitamin D supplement presented severe vitamin D deficiency, only a small number of children presented vitamin D deficiency (n=16 (13.4%)), and no signs of overload were observed, while one half of non-supplemented children (n=95 (50.5%)) presented at least vitamin D deficiency at the end of winter. These results support the need for vitamin D supplementation during winter in children aged 6-10years., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Beyond the classically described regulation of calcium and bone metabolism, vitamin D is a neurosteroid hormone essential to neurophysiological function (regulation of neurotransmitters and neurotrophins) with anti-inflammatory and antioxidant neuroprotective action. In contrast, hypovitaminosis D, which is extremely frequent in the elderly, may result in neurological dysfunction and may explain part of the cognitive disorders in this population. Epidemiology is consistent with this notion and has repeatedly shown an association between hypovitaminosis D and cognitive decline, either in the general population or in Alzheimer's patients. Preliminary intervention trials confirm the causal relationship and quantify the cognitive effect of vitamin D supplementation in the elderly. This raises prospects for primary/secondary prevention of cognitive decline by exogenous supplies of vitamin D. In particular, although current anti-dementia drugs are only symptomatic, future treatment options could rely on drug combinations preventing several neurodegenerative mechanisms at once. As such, vitamin D enhances the efficacy of memantine in terms of neuronal protection and prevention of cognitive decline in Alzheimer's disease., (© Société de Biologie, 2014.)

The confinement can lead to an important limitation of sun exposure of the prisoners. This limitation can lead to a deficit in vitamin D, source of diverse disorders. Diffuse pains of members and of joints are the most classics troubles. The association of vitamin D deficiency and psychiatric disorders is frequent but badly known. Even if there is still no evidence indicating a cause and effect relationship between vitamin D deficiency and depressive episodes, the contribution of vitamin D deficiency in the arisen of a depression has to be considered. The treatment of vitamin D deficiency cannot, in itself, constitute a treatment of the depressive disorder but contributes to the improvement of the whole status The psychiatric follow-up remains indispensable, in particular because of the suicidal risk, particularly present in prison., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Vitamin D plays a role in the synthesis of antibacterial peptids and in autophagy. Several studies have shown that low levels of vitamin D are associated with the susceptibility and the severity of acute infections on one hand, and with an unfavorable outcome of some chronic infections (such as HIV infection). Vitamin D supplementation improves response to treatment of some viral (such as chronic hepatitis C infection) or bacterial infections (such as pulmonar tuberculosis). Vitamin D supplementation demonstrated no benefit in reducing the incidence of pulmonary infections. The target level of vitamin D to be reached after supplementation is not known yet., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Vitamin D deficiency is associated with a higher risk of multiple sclerosis and also with a higher relapse rate as well as a higher number of MRI lesions. Elders with vitamin D deficiency have worse cognitive performance. Vitamin D deficiency is a risk factor for developing Alzheimer's disease. Ischemic stroke are more frequent and more severe in patients with low vitamin D levels. Carotid atherosclerosis is more frequent and more severe in patients with vitamin D deficiency. Vitamin D deficiency is associated with a higher risk and worse prognosis of Parkinson's disease. In the different neurological disorders discussed herein, gene polymorphisms that could alter vitamin D metabolism are also associated with a higher incidence or a worse disease prognosis. Despite the links between vitamin D deficiency and the risks of developing neurological disorders, there is, to date, no proof that supplementation could alter the course of these diseases., (Copyright © 2013. Published by Elsevier Masson SAS.)

Few interventional studies have reported a positive effect of native vitamin D supplementation on intermediary parameters of insulin resistance, of cardiovascular risk and on major cardiovascular events and mortality., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

There is a recent renewed interest in vitamin D, due to its description as a hormone with a positive impact on global health. Even though many former epidemiological studies have suggested a possible link between a low vitamin D status and the risk of developing chronic diseases, recent data have proven to be more discordant or modest. Looking forward to clearly needed randomized intervention studies, optimal vitamin D status and intakes should be defined on the basis of the vitamin D indisputable effects on calcium homeostasis and skeletal mineralization.

Calcitriol and analogs inhibit renin-angiotensin system, which has a pivotal role in glomerular and tubulo-interstitial damages and proteinuria, and inhibit NF-κB activation which is known to play an important role in renal diseases by promoting inflammation and fibrogenesis. Vitamin D presents interesting pleiotropic effects for the CKD patient (reduction of mortality, antiproteinuric effect and anti-inflammatory properties). "Native" vitamin D (cholecalciferol or ergocalciferol) administration in these patients also decrease parathyroid hormone levels. Native vitamin D administration in CKD patients is safe and does not lead to increased risk of vascular calcification, despite the known hypercalcemic and hyperphosphoremic properties of the molecule in its active form. Native vitamin D administration is not associated with an increased risk of renal stones, at pharmacological doses and without important concomitant administration of calcium salts. In the field of renal transplantation, experimental studies show that vitamin D analogs have a protective role against acute rejection but clinical studies remain mainly observational., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Vitamin D acts at several levels in the immune systems to maintain immune tolerance. Vitamin D deficiency is a plausible environmental risk factor for autoimmune disease. Basic, genetic and epidemiological studies indicate a potential role of vitamin D in the prevention and the treatment of autoimmune diseases. Most of the epidemiological studies are cross-sectional, so that they are insufficient to establish a direct link between vitamin D deficiency and both disease risk and disease activity. Randomized, controlled trials are necessary., (Copyright © 2013. Published by Elsevier Masson SAS.)

Vitamin D insufficiency is characterized, since 2005, by 25(OH)D concentration less than 75 nmol/L (or 30 ng/mL). Vitamin D could interfere with many mechanisms involved in preeclampsia's pathogenesis including trophoblastic invasion and immunomodulation as well as blood pressure control and proteinuria. Occurrence of preeclampsia and gestational diabetes seems to be linked to vitamin D deficiency but recent data in the literature are contradictory. Vitamin D supplementation during pregnancy is controversial. Some societies consider it unnecessary and others recommend up to 2000 UI/d. There is no reported case of teratogenicity linked with vitamin D intake., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Vitamin D has been traditionally considered as important for skeletal health. However, during the past decade, numerous research findings have revealed that vitamin D may have beneficial effects on extraskeletal tissues as well. Vitamin D deficiency is now recognized as a worldwide issue. The prevalence of vitamin D deficiency or insufficiency depends on the threshold used to define vitamin D deficiency or insufficiency. However, whatever the threshold (20, 30 or 40 ng/mL), the prevalence is high in France as elsewhere. Vitamin D status is now based on the measurement of 25-hydroxyvitamin D [25(OH)D] concentration. This assay does not seem justified in most situations encountered in clinical practice, and its overprescription generates a significant cost to public health. This is why Official Clinical Societies try to define: (a) target populations for which a determination is required (every situation in which the therapeutic goal requires an optimal serum 25(OH)D level for an appropriate medical care) and which require specific treatment; (b) target populations for which the risk of deficit is important (due to insufficient daily intake) and may benefit from preventive pharmaceutical supplementation without prior testing (infants, pregnant women, patients over 65...)., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Infantile Nutritional Rickets has disappeared almost completely in France since 1992 as vitamin D enriched formula availability and previous vitamin D supplementation of infants. The search of evocative symptoms of rickets should be a routine procedure in infants, in particular in case of insufficient vitamin D intake i.e. breastfeeding, and the possibility of vitamin D resistant rickets. Hypocalcaemia occurs not only at the first but also the advanced stages of vitamin D deficiency, and may be responsible for severe cardiologic, neurologic or respiratory complications with possibility of infant death. For the young children between 1 and 5 years and for adolescents, vitamin D insufficiency is responsible for poor skeletal mineralization, loss of bone strength, and a reduction of peak of bone mineral mass at the end of puberty. The new Dietary Reference Intakes (DRI, 2011) increased greatly the Recommended Dietary allowances (RDA) from 200 to 600 IU/d (15 μg/d) for individuals from 1 to 70 years of age. These levels are not reached in winter, even in countries, like USA and Canada, where vitamin D milk fortification is mandatory and others like Japan and North-European countries despite high fish consumption. From 1 to 5 years of age and during adolescence, a winter vitamin D3 supplementation is necessary with 80.000 or 100.000 IU periodic loads every 3 months i.e. in November and February. In cases of an underlying risk, i.e. insufficient vitamin D photosynthesis in summertime (dark skin, wearing heavily skin-covering clothes, or several skin diseases), or digestive, renal or nutritional pathologies, use of some drugs, loading dose of 80.000 or 100.000 IU, every 3 months should be administered over the year., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Insufficient serum levels of 25-hydroxyvitamin D [25(OH)D] is a risk factor for osteoporosis. A new paradigm is emerging with the locally synthesized 1,25(OH)2D within osteoblasts and osteoclasts as the essential pathway for the effects of 25(OH)D in regulating bone remodeling via direct or indirect activation of the specific receptor VDR. Vitamin D has positive effects on fracture risk, muscular function and risk of falls; these effects are observed when serum levels of 25(OH)D are above 30 ng/ml (75 nmol/l). Vitamin D dosing interval may be relevant for reducing the risk of fracture, with evidence suggesting positive effects with short intervals of 3 months or less. It is recommended to maintain an optimal serum level of 25(OH)D when managing patients with osteoporosis or at risk of this bone disease., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Vitamin D deficiency occurs rather commonly among healthy pregnant women, newborns and young children, especially in certain risk groups. Since vitamin D plays a role in calcium and phosphor metabolism essential for bone health and in the physiopathology of some autoimmune diseases it seems important to provide recommendations for prevention of vitamin D deficiency. Risk factors include maternal vitamin D deficiency, low intake of fortified food, eg. breastfeeding, low compliance of supplementation, dark skin, inadequate sun exposure, premature birth, overweight, living at high latitude. The aim of this paper is to summarize available data of vitamin D sources, known situations in which deficiency is common and published guidelines on vitamin D supplementation, and translate this information in recommendations for prevention of vitamin D deficiency in healthy paediatric population in Flanders. Infants should receive an oral supplementation of 400 IU/day of vitamin D from birth and this should be continued till the age of 6 years. In cases of dark skin the dose should be 600 IU/day. An healthy life style with outdoor activities and associated sun exposure and intake of fortified nutrition should be advised. The implementation should be promoted by all healthcare professionals working with young children.

Vitamin D is well known for its beneficial effects on phosphocalcic homeostasis. The discovery of the role of vitamin D in cancers, infections, cardiovascular or autoimmune pathologies have promoted interest for this molecule. Skin and vitamin D are closely related. The skin is not only the site of vitamin D synthesis, but also a target organ as calcitriol plays an important hormonal and regulatory role, acting on cell proliferation, differentiation and immunomodulation. Furthermore, vitamin D influences the incidence and therapeutic response of certain dermatoses. In addition, many medical situations, mainly dermatological, require strict photoprotection and may therefore indirectly be responsible for a vitamin D deficiency in patients. The current role of vitamin D in skin cancers, inflammatory and autoimmune skin diseases is summarized.

Vitamin D plays a clearly defined role in phosphorus, calcium and bone metabolism. In addition to its effects on cellular proliferation and differentiation, and on immunity, it appears to exert other action, poorly understood to date, on human physiology and disease. A number of epidemiological studies have demonstrated a protective role of sun exposure with regard to the incidence of certain immune diseases and cancer, and upon the related mortality rates. Furthermore, over the last 10 years, studies have purported to find levels judged "inadequate" in numerous populations, and, in the absence of any strict scientific arguments, a correlation was established by certain authors between supposedly "inadequate" levels, sun exposure and risk of cancer. However, analysis of the literature shows that there is in fact no precise and consensual definition of normal ranges and that the notion of inadequacy was created artificially using assay techniques lacking in sensitivity and reproducibility. Photosynthesis of vitamin D can in fact be considered perfectly adequate in the majority of populations. However, greater care is needed with elderly subjects and with subjects exposed very little to sunlight. Current studies show that the means of photoprotection used in everyday life do not adversely affect such photosynthesis. In the event of documented vitamin D deficiency, oral supplements should be given, and exposure to natural or artificial UV radiation should not be prescribed. Ultraviolet radiation has been shown to be carcinogenic and responsible for the onset of most skin cancers, and the population must be warned against misleading advertising from the tanning industry. Care should also be taken with regard to the potential harmful effects of inappropriate vitamin D supplementation., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Besides its role in bone metabolism, vitamin D shows properties on autoimmune, oncological, cardiovascular, metabolic, or infectious diseases. In this article, we talk about interpellant relationships between vitamin D and HIV. This hormone plays an important role in HIV infection, as much at a skeletal level than in the course of the disease itself. First, we notice that a low vitamin D status is currently associated with HIV infection. Moreover, it is now known that low rate of 1,25-dihydroxyvitamin D in HIV patients is associated with advanced clinical HIV infection and increased mortality. Thus, vitamin D deficiency has to be considered as an important factor in HIV progression. Indeed, vitamin D increases macrophage activity, in some way through autophagy, and this process can inhibit HIV-1 infection. Then we consider the implications of antiretroviral therapies on vitamin D metabolism. We finally evaluate the benefits of a vitamin D supplementation in HIV + patients.

Patients with chronic kidney disease exhibit a high mortality risk that is not fully explained by the classical cardiovascular risk factors. Vitamin D deficiency highly prevalent among CKD patients is independently associated with an increased mortality risk in this population. Advances in the understanding of vitamin D physiology dramatically changed the view on the role of this vitamin in kidney disease. Extra-renal actions on a variety of tissues have been identified. By its cardiovascular effects for instance, correction of vitamin D insufficiency might help to reduce the excess of mortality among patients with chronic kidney disease. This article summarizes the sum of knowledge on the roles of vitamin D in kidney disease. Recommendations on screening and substitution with vitamin D in this high-risk population are then proposed.

The quasi-ubiquitous distribution of vitamin D receptors in the human tissues and the high prevalence of vitamin D deficiency worldwide have generated much enthusiasm about the opportunity of cardiovascular disease prevention through vitamin D supplementation. However, reported associations between vitamin D and cardiovascular disease present important limitations and are prone to confounding and reverse causation. Results from ongoing randomized clinical trials testing the efficacy of vitamin D supplementation to reduce cardiovascular events will not be available before year 2015. This article reviews the epidemiology of vitamin D and provides a brief overview on the relationship between vitamin D and cardiovascular disease.

Result of renewed interest due to the large amount of literature that reported numerous epidemiological data demonstrating the high prevalence of vitamin D deficiency, the number of prescriptions of serum vitamin D assays has grown exponentially in recent years with a cost for health insurance that increased almost fivefold in four years. The quantitative and qualitative analysis of assays carried out from 2007 to 2011 in a French university adult short-stay hospital shows changes in practices not only quantitatively but also qualitatively resulting in an overtime increase in the frequency of prescriptions in patients younger, less vitamin D deficient and more frequently male. In the absence of French guidelines, this development cannot be qualified as deviant but justifies the urgent need to establish evidence-based recommendations for good prescriptions and adequate assays of blood vitamin D.

Introduction: Recent reports demonstrate the implication of vitamin D in multiple sclerosis (MS)., Methods: In a multicentric regional study (Poitou-Charentes area) during the first trimester 2010, we measured the 25-OH vitamin D serum level in 170 consecutive MS patients, and in 170 controls matched for age (±4 years), sex and date of blood sample analysis. We searched for correlations between 25-OH vitamin D serum levels and the MS form, the disability (EDSS), the relapse rate during the previous year and the presence and number of enhancing lesions on T1-weighted MRI dating less than 12 months in relapsing MS., Results: Hypovitaminosis D was very frequent in MS patients and 25-OH vitamin D serum level was significantly lower (14.5 ± 9.2 mcg/mL) in MS patients than in the control group (16.7 ± 9.6 mcg/mL). This serum level was inversely correlated with the degree of disability measured with EDSS score and was lower in secondary progressive (RR-SP) and primary progressive (PP) MS than in relapsing MS (RR). No correlation was found between 25-OH vit D serum level and relapse rate during the previous year in RR MS and the presence and number of enhancing lesions on T1-weighted MRI dating from less than 12 months., Conclusion: 25-OH vit D serum level is very low in MS, mainly in RR-SP and PP MS and is correlated with disability. This suggests MS patients should be screened for vitamin D deficiency and given supplementation systematically when hypovitaminosis D is discovered., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

Background: Primary hyperparathyroidism (PHPT) associates hypocalcemia and hypophosphatemia secondary to parathyroid hormone (PTH) excess. PHPT is asymptomatic for 80% of patients and responsible for a decrease in bone mineral density particularly in women. Vitamin D deficiency increases the risk of bone fractures., Methods: We performed a prospective analysis of patients with PHPT in order to evaluate the prevalence of vitamin D deficiency. We determined the effects of vitamin D deficiency on bone metabolism: calcium, phosphate and PTH levels. We also analyzed biochemical markers of bone remodeling and bone mineral density (BMD) before and 6 months after vitamin D replacement., Results: 75 patients with PHPT were identified: 38 patients with vitamin D deficiency but only 22 patients could be followed (G1). 14 patients with a normal level of vitamin D were followed (G2). Prevalence of vitamin D deficiency was 51%. Calcium and phosphate levels were similar into both groups. PTH levels were higher in the G1 group. Calciuria was significantly lower in the G1. For markers of bone formation (fragments of collagen CTX and alkaline phosphatase): osteocalcine levels were higher in G1 group. For bone resorption: télopeptides levels were significantly higher in the G1 group. T score was significantly lower in this group, favoring a significant osseous attack. After 6 months of substitution with vitamin D, calcium decreased and hypophosphatemia normalized. PTH levels decreased (-50.7%). Calciuria increased without risks of urinary lithiasis. Bone mineral density loss decreased while markers of bone turn over increased., Discussion: Vitamin D deficiency increases the risk of bone fragility in PHPT. Few data are available in France concerning the prevalence of vitamin D deficiency in PHPT. Our results were similar to data in other countries. Vitamin D replacement with regular monitoring of calcium and calciuria levels is beneficial for metabolic and hormonal status, improves bone density, without systematic opposing effects. The follow-up of effectiveness by BMD could be associated with measurement of markers of bone remodeling., Conclusion: In asymptomatic PHPT, particularly those for which surgery is not indicated, measurement of 25 OH Vitamin D should be systematic. It is recommended before surgery., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

There is a recent renewed interest in vitamin D metabolism and pathophysiology, due to its recent description as a hormone with a positive impact on global health rather than a strictly bone hormone: vitamin D could be a protective factor against infection, autoimmunity, cardiovascular morbidity, and cancer. By contrast, vitamin D deficiency appears to be increasingly frequent worldwide. We propose a review of these new aspects of vitamin D metabolism, with a focus on vitamin D status in a local pediatric cohort. There is an urgent need for revisiting current guidelines on vitamin D supplementation and for closely monitoring serum vitamin D in children with chronic diseases, i.e., at greater risk of cardiovascular impairment, bone morbidity, infectious disease, and acute inflammation., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

The understanding of the role of vitamin D in maintaining good health has considerably increased in the recent years. There is a growing evidence that vitamin D has not only a beneficial effect to prevent osteoporosis and the risk of falls in the elderly, but also may reduce incidence of cancers, infections, autoimmune, cardiovascular and neurologic diseases, and psychiatric disorders. Laboratory studies yield a biological plausibility for a positive contribution of vitamin D to brain functions: vitamin D receptor and 1,α-hydroxylase, the terminal calcitriol-activating enzyme, are widely distributed in both the fetal and adult brain. Vitamin D may be involved in neuroprotection, control of proinflammatory cytokine induced cognitive dysfunction and synthesis of calcium-binding proteins and neurotransmitter acetylcholine. However, the observational studies conducted in humans are still inconclusive, given the various tests of the cognitive functions that have been used, the performance of the studies either in patients or in healthy subjects, and different designs and/or confounding factors. The role of the vitamin D receptor in the pathophysiology of cognitive decline, incidence of Alzheimer's disease or vascular dementia and/or cognitive decline with respect to previous plasma 25OHD concentration, and the effect on cognition of vitamin D supplementation should be explored in further studies.

Vitamin D deficiency affects almost 50 % of the population worldwide. Besides its classical effects on bone and calcium metabolism, vitamin D displays a wide spectrum of non classical effects. Among these effects, those targeting the cardiovascular system are mostly documented by observational, experimental and small intervention trials that most often evaluated intermediate parameters. The time has now come for large placebo-controlled trials targeting clinical endpoints such as the incidence of major cardiovascular events and mortality., (Copyright 2010 Elsevier Masson SAS. All rights reserved.)

Blood levels of 25 hydroxyvitamin D (25(OH) vit D) were measured in 332 patients (192 women, mean age 69.1 +/- 17.8 SD and 140 men, 61.9 +/- 18) hospitalized in C.H.U. Brugmann for acute diseases without any link with vitamin D supply and/or metabolism. More than 60% of this population presented with serum concentrations below the lower limit of normal (12 ng/ml) whereas than less than 5% reached 30 ng/ml, a level generally recommended to avoid vitamin D insufficiency. The inverse relationship between blood levels of 25(OH) vit D and parathyroid hormone reinforced the opinion that 30 ng/ml is the minimum to reach to avoid secondary hyperparathyroidism. Young patients are nor at a lesser risk of vitamin D deficiency than the older patients, women showed a lesser deficiency than men. Factors likely to have contributed to vitamin D deficiency are a low social status and dark skin. In countries without abundant sun exposure, such as Belgium, systematic administration of vitamin D supplement is recommended, in particular in subjects at risk of deficiency, during autumn and winter, including all ages of life.