Introdução: A vitamina D tem ações pleiotrópicas em muitas doenças crônicas. A expressão do receptor da vitamina D (VDR - vitamin D receptor) em diversas células do sistema imune reforça a possível influência da vitamina D nas doenças autoimunes. Polimorfismos genéticos localizados no gene VDR podem determinar alterações nos mecanismos de ação da vitamina D, porém com resultados ainda pouco conhecidos. O polimorfismo BsmI do gene VDR foi associado com lúpus eritematoso sistêmico (LES) em pacientes asiáticos. Estudos com pacientes lúpicos no Brasil ainda não foram realizados. Objetivos: Investigar a possibilidade dos polimorfismos BsmI e FokI do gene VDR aumentarem o risco para o desenvolvimento do LES e avaliar a possível associação destes polimorfismos com manifestações clínicas e laboratoriais da doença. Determinar os níveis séricos da 25-hidroxivitamina D [25(OH)D)] nos pacientes e investigar a possível associação das suas concentrações com os polimorfismos estudados e expressões clínicas e laboratoriais do LES. Materiais e métodos: Estudo caso-controle envolvendo 195 pacientes com LES e 201 controles saudáveis da mesma área geográfica. Foram pesquisados os polimorfismos BsmI e FokI do gene VDR. Os níveis séricos da 25(OH)D foram dosados nos casos. A genotipagem foi realizada por Restriction Fragment Length Polymorphism-Polimerase Chain Reaction (RFLP-PCR), usando primers e enzimas de restrição específicas para cada polimorfismo. A dosagem da 25(OH)D foi realizada por quimioluminescência. Os dados clínicos e laboratoriais foram coletados dos prontuários. Resultados: Não houve diferença estatisticamente significativa nas frequências genotípicas e alélicas dos polimorfismos BsmI e FokI entre casos e controles eurodescendentes. Não houve associação entre as manifestações clínicas e laboratoriais do LES e os polimorfismos estudados. Os níveis séricos médios da 25(OH)D foram de 25,51±11,43 ng/ml nos pacientes com LES. Quando os pacientes foram classificados pelo estado de vitamina D, a seguinte distribuição foi observada: 55 (30,4%) normais (≥30 ng/ml), 63 (34,8%) insuficientes (20-30 ng/ml), 52 (28,7%) deficientes (<20 ng/ml) e 11 (6,1%) com níveis criticamente baixos (<10 ng/ml). Cinquenta e seis por cento dos pacientes com deficiência estavam usando pelo menos 800 UI de vitamina D por dia. Baseada na distribuição genotípica, a concentração da 25(OH)D foi significativamente maior nos pacientes com genótipo f/f, quando comparados com os pacientes com genótipo F/F (31,614,1 ng/ml versus 23,09,2 ng/ml, p=0,004). Níveis de vitamina D não foram associados com aspectos clínicos e laboratoriais do LES. Conclusões: Os polimorfismos BsmI e FokI não apresentaram associação com LES nos nossos pacientes eurodescendentes estudados. O polimorfimo FokI mostrou influência significativa nos níveis da 25(OH)D, o que reforça o papel deste polimorfismo na atividade funcional do VDR. Este achado poderia ser considerado em futuros estudos clínicos e experimentais envolvendo dosagem da vitamina D. A concentração da 25(OH)D necessária para manter o bom funcionamento do sistema musculoesquelético, cardiovascular e imunológico deveria ser individualizada para cada paciente e novas orientações sobre a suplementação de vitamina D poderiam ter que levar em consideração a ancestralidade genética. Assim, estudos adicionais são necessários para estabelecer definições dos níveis ideais de vitamina D geneticamente especificados. / Introduction: Vitamin D has pleiotropic actions on many chronic diseases. The expression of the VDR (vitamin D receptor) in various cells of the immune system strengthens the possible influence of vitamin D on autoimmune diseases. Genetic polymorphisms located in VDR gene may determine changes in the mechanisms of action of vitamin D, but with results still unknown. The BsmI VDR polymorphism was associated with systemic lupus erythematosus (SLE) in Asian patients. Studies with SLE patients in Brazil have not been conducted. Objectives: To investigate the possibility of BsmI and FokI polymorphisms of VDR gene causing increased risk for development of SLE and to evaluate the possible association of these polymorphisms with clinical and laboratory manifestations of the disease. To determine serum levels of 25-hydroxyvitamin D [25(OH)D)] in patients and to investigate the possible association of their concentrations with the studied polymorphisms and clinical and laboratory expressions of SLE. Materials and methods: Case-control study involving 195 SLE patients and 201 healthy controls from the same geographical area. The BsmI and FokI polymorphisms of VDR gene were studied. Serum 25(OH)D levels were measured in the cases. Genotyping was performed by Restriction Fragment Length Polymorphism-Polymerase Chain Reaction (RFLP-PCR), using primers and restriction enzymes specific for each polymorphism. The measurement of 25(OH)D was performed by chemiluminescence. The clinical and laboratory data were collected from medical records. Results: There was no statistically significant difference in genotypic and allelic frequencies of BsmI and FokI polymorphisms among European-derived cases and controls. There was no association between clinical and laboratory features in SLE patients and the studied polymorphisms. The mean serum levels of 25(OH)D were 25.51±11.43 ng/ml in SLE patients. When patients were classified according to vitamin D status, the following distribution was observed: 55 (30.4%) had normal (≥30 ng/ml), 63 (34.8%) insufficient (20-30 ng/ml), 52 (28.7%) deficient (<20 ng/ml) and 11 (6,1%) critically low serum levels (<10 ng/ml). Fifty six percent of patients with deficiency received at least 800 IU of vitamin D per day. Based on genotype distribution, 25(OH)D levels were significantly higher in patients carrying the f/f genotype, when compared to patients carrying the F/F genotype (31.614.1 ng/ml versus 23.09.2 ng/ml, p=0.004). Vitamin D levels were not associated with clinical and laboratory features of SLE. Conclusions: The BsmI and FokI polymorphisms did not present association with SLE in our European-derived studied patients. The FokI polymorphism showed significant influence on 25(OH)D levels, reinforcing its role in functional activity of VDR. This finding may be considered in future clinical and experimental studies involving vitamin D measurements. Serum concentrations of 25(OH)D required to maintain optimal musculoskeletal, cardiovascular and immune health should be individualized for each patient and new guidelines about vitamin D supplementation may have to take into consideration the individual genetic background. Genetic-specific definitions of ideal levels of vitamin D in SLE should therefore be established in future studies.

During the industrialization of the 19th century the negative health effects of vitamin D was discovered as children in the cities developed osteomalacia or more commonly known as rickets caused by vitamin D deficiency. Vitamin D is produced in the skin from 7-dehydrocholesterol during sun-exposure and enhances intestinal phosphor and calcium absorption thus enhancing the bone remodeling process. Now, in the 21st century, Vitamin D is still relevant as positive health effects have been recognized and with it an increased number of samples and a demand for accurate analyzing. Vitamin D is commonly believed to be sensitive to ultraviolet radiation in serum and blood samples and therefore have traditionally been kept protected from light exposure from the time of sampling until the finished analyze. However recent studies have proven 25- hydroxyvitamin D (25[OH]D) to be stable in both whole blood and serum. As previous studies have been primarily conducted in research laboratories with the aim to study vitamin D under specific research-laboratory conditions the aim of this study was to study the stability of 25[OH]D in serum and whole blood within both primary care- and hospital laboratories under normal and exaggerated conditions with the purpose to evaluate possible pre-analytical issues with everyday handling processes. The assay used was high pressure liquid chromatography-tandem mass spectrometry, HPLCMS/MS, and the sought analytes 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3, 25[OH]D2 and 25[OH]D3. The results showed that 25-hydroxyvitamin D is stable in serum for 24 hours at room temperature whilst exposed to light both ultraviolet and fluorescent. The analyte is also stable for up to four freeze-thaw cycles rendering the process of light-protection and samples frozen immediately after centrifugation superfluous. The results also ensure reliable results even if samples are accidently left on benchtops or saved refrozen to be reanalyzed at a later date. / Under den industriella revolutionen på 1800 talet upptäcktes de negativa hälsoeffekterna av vitamin D-brist då barnen i städerna utvecklade rakit (osteomalaci) eller engelska sjukan som sjukdomen också kallas på grund av brist på sol och D-vitamin. Vitamin D produceras i huden från 7-dehydrokolesterol vid solexponering och ökar upptaget av fosfor och kalcium i tarmen som i sin tur förbättrar återuppbyggnaden av skelettet. Vitamin D är fortfarande aktuell även nu i vår tid men då för dess nyupptäckta hälsofrämjande egenskaper som till exempel förebyggandet av coloncancer. Detta medför även en ökning av antalet analyser och kräver därmed en adekvat analysmetod. Traditionellt har det antagits att vitamin D är ljuskänsligt i alla former därför har blod och serum ljusskyddats, från provtagningstillfället fram tills dess att analysen är utförd. Dock har nya studier visat att 25-hydroxyvitamin D (25[OH]D) är mycket stabilt bundet till vitamindbindande protein i både serum och helblod. Syftet med studien var att utvärdera om 25[OH]D i serum och helblod behöver ljusskddas genom att studera stabiliteten hos 25[OH]D i både serum och helblod under normala primärvårdslaboratorie- och sjukhuslaboratorieförhållanden samt under extrema förhållanden för att utvärdera eventuella preanalytiska problem eller fel relaterade till den vardagliga hanteringen av vitamin D prover. Proverna analyserades med högupplösande vätskekromatografi-tandem masspektrometri, HPLC-MS/MS, och de sökta analyterna var 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3, 25[OH]D2 och 25[OH]D3. Resultat från studien visade att 25-hydroxyvitamin D är stabilt i serum i 24 timmar i rumstemperatur med ljusexponering från både ultraviolett och fluorescerande ljus. 25-hydroxyvitamin D är även stabil i serum upp till fyra frys- och tiningscykler. Detta gör att provhanteringen kan förenklas genom att dessa prover inte behöver ljusskyddas samt att serumet ej behöver frysas in direkt efter centrifugering. Resultatet säkerställer även tillförlitliga resultat om prover lämnas framme på bänken av misstag eller om prover behöver sparas och frysas om för att analyseras vid senare tillfälle.

Vitamin D insufficiency remains a costly pandemic in veterans. Treatment requires achievement of desired 25-hydroxyvitamin D [25(OH)D] concentrations. The frequency with which 25(OH)D should be measured following treatment remains speculative. A retrospective analysis of veterans with vitamin D insufficiency was conducted. The group was stratified on the basis of initial 25(OH)D and assessed for frequency of follow-up 25(OH)D concentrations. Over 3 years, 278 patients with insufficient 25(OH)D concentrations were identified. Of these, 87 (31%) patients had subsequent levels assessed in the year following initial documentation of vitamin D insufficiency. The likelihood of follow-up testing was unrelated to the initial vitamin D level. In the patients with follow-up 25(OH)D levels, 90% eventually achieved a serum level of 30 ng/mL or greater. Veterans with vitamin D insufficiency have inadequate serial monitoring of 25(OH)D concentrations.

The increased number of international immigrants and associated global problems of health deterioration and vitamin D (vitD) deficiency/insufficiency may lead to significant burdens for host countries. This thesis investigated immigrants’ health deterioration and vitD status through a comprehensive analysis of Canadian national vitD data, systematic evaluation of the quality/content of clinical practice guidelines, and global systematic review of vitD status and determinants among first-generation immigrants. Immigrants had lower serum 25-hydroxyvitamin D (S-25(OH)D) and higher melanin levels than non-immigrants. S-25(OH)D levels improved over time, with ethnicity the main factor explaining variations. The longer immigrants lived in Canada, the higher the prevalence of chronic diseases (CDs), potentially reflecting health deterioration. Low levels of accumulated S-25(OH)D may impact CD-related biomarkers, partially explaining immigrants’ health deterioration over time. Local and international guidance regarding immigrants’ vitD deficiency/insufficiency was lacking. Improving immigrants’ vitD status requires prevention and intervention programs (e.g., vitD supplementation/screening), relevant national/international guidelines, and longitudinal research clarifying the complex bidirectional association between S-25(OH)D and CDs.

Background: Vitamin D deficiency is a concern in the US. Association between vitamin D status and metabolic syndrome (MetS), insulin resistance (IR), and inflammation is unclear in children. Objective: The relationship between serum vitamin D and MetS, C-reactive protein (CRP), and Homeostatic Model Assessment-IR (HOMA-IR) was investigated. Design: Data from 3 cycles of National Health and Nutrition Examination Survey, 2001-2006 for 3700 (1820, boys; 1880, girls) children and adolescents, aged 12-17 y were used to assess prevalence of vitamin D deficiency (<20 ng>/mL) and association between serum vitamin D and prevalence of MetS, various components of MetS, CRP, and HOMA-IR using multivariate regression models. Results: Overall, prevalences of MetS and vitamin D deficiency were 6.1% and 30.5%, respectively. Prevalence of vitamin D deficiency was higher in girls (52%), blacks (74%), non-supplement users (50%), persons who were examined in winter (56%), and persons in the low poverty income ratio group (57%) compared to their counterparts. Serum vitamin D was inversely associated with waist circumference (P<0.001), systolic blood pressure (P=0.009), and HOMA-IR (P=0.003) and positively associated with HDL-cholesterol (P<0.001). Children with lowest serum vitamin D are at increased risk for MetS (P=0.04; OR 2.26; 95% CI: 1.11, 4.61). Serum vitamin D was not related to CRP (P<0.10). Conclusions: Children with poor vitamin D status are at increased risk for MetS and IR. Because of negative health outcomes associated with MetS and poor vitamin D status when existed individually or in combination, early detection and intervention of these conditions are paramount, especially in children.

Abstract Vitamin D deficiency, obesity and short telomere length are reported to be associated with increased risk of metabolic diseases and all-cause mortality, through modulation of inflammatory pathways. The season of blood sampling, obesity and physical activity have been identified as determinants of 25-hydroxyvitamin D [25(OH)D], but their association with 25(OH)D2 (D2) and 25(OH)D3 (D3) is still poorly understood. In addition, relationships between 25(OH)D, body mass index (BMI), inflammation, and leukocyte telomere length (LTL) has not been previously established. A better understanding of the determinants, risk factors of vitamin D deficiency, and their relationship with BMI, inflammation, and LTL is needed. The study was based on the 31-year follow-up study of the Northern Finland Birth Cohort 1966 (N=4,758). Statistical analyses were used to 1) examine potential determinants of D2 and D3, and identify risk factors associated with hypovitaminosis D, 2) investigate the relationship of 25(OH)D and BMI with LTL and test whether it is independent of inflammatory pathways and, 3) assess how the association of BMI with inflammatory biomarkers might be mediated through 25(OH)D. Our results showed that D2 contributed 5% and D3 95% of the total 25(OH)D concentrations. When examined, the determinants for each isoform, periods of low sunlight exposure associated with increased D2, but with decreased D3. Oral contraceptives associated with increased concentrations of both. We confirmed the known risk factors of low vitamin D: low sunlight periods, residing in northern latitudes, and physical inactivity. Serum 25(OH)D was not an important determinant of LTL, and inflammation may partly mediate the BMI-LTL association. Higher serum 25(OH)D was inversely associated with inflammatory biomarkers, and the association between BMI and biomarkers was modestly mediated through lowered 25(OH)D. In conclusion, our results support the role of known risk factors in vitamin D deficiency and add information on specific determinants of D2 and D3. 25(OH)D did not associate with LTL in young adulthood. We have also provided new insights into a plausible role of vitamin D in BMI associated inflammation. An improved understanding of the role of vitamin D benefits public health in many ways (it can help prevent vitamin D deficiency by implementing lifestyle modification and supplementation). / Tiivistelmä D-vitamiinin puutos, lihavuus ja lyhyt telomeerien pituus liittyvät mahdollisesti lisääntyneeseen riskiin sairastua metabolisiin sairauksiin sekä yleisemmin kuolleisuuteen. Eräs selitys tälle voi löytyä tulehdustekijöistä. Lihavuuden, liikunnan puutteen ja verinäytteenoton ajankohdan tiedetään vaikuttavan 25-hydroksi-D-vitamiinin [25(OH)D]-pitoisuuteen, mutta niiden yhteys D-vitamiinin isomuotoihin (D2, D3) on vielä huonosti tunnettu. Aiemmin ei ole selvitetty 25(OH)D:n, painoindeksin (BMI), tulehduksen ja leukosyyttien telomeerien pituuden (LTL) välisiä yhteyksiä, ja siksi näistä tarvitaan lisätutkimusta. Tutkimusaineistona oli Pohjois-Suomen 1966 syntymäkohortin, 31-vuoden seurantaan osallistuneet henkilöt (N=4,758). Tutkimuksessa keskityttiin 1) selvittämään D2- ja D3-vitamiinipitoisuuksien määrittäviä tekijöitä ja tunnistamaan D-vitamiinin puutteeseen liittyviä riskitekijöitä, 2) tutkimaan 25(OH)D-pitoisuuden ja BMI:n suhdetta LTL:n kanssa sekä testaamaan, onko suhde riippumaton tulehduksellisista tekijöistä ja 3) arvioimaan ilmeneekö BMI:n ja tulehdussytokiinien välinen yhteys 25(OH)D-pitoisuuden kautta. Tutkimus osoitti, että D2-isomuodon osuus oli 5 % ja D3:n osuus 95 % koko 25(OH)D-pitoisuudesta. Näitä isomuotoja määrittäviä tekijöitä tutkittaessa havaittiin, että vähäisellä auringonvalolle altistumisella on todennäköisesti yhteys lisääntyneeseen D2-pitoisuuteen, mutta alhaisempaan D3-pitoisuuteen. Suun kautta otettavien ehkäisypillereiden käytöllä oli yhteys molempien muotojen lisääntyneisiin pitoisuuksiin. Tutkimus vahvisti alhaisten D-vitamiinipitoisuuksien tunnetut riskitekijät: lyhyt altistus auringon valolle sekä fyysinen passiivisuus. 25(OH)D-pitoisuus ei ollut yhteydessä LTL:ään mutta tulehdus näytti osittain vaikuttavan BMI-LTL-assosiaatioon. Korkeampi 25(OH)D-pitoisuus yhdistyi matalampiin tulehdussytokiinipitoisuuksiin, kun taas matala 25(OH)D-pitoisuus muokkasi BMI:n ja biomarkkereiden välisisiä yhteyksiä, tosin heikosti. Yhteenvetona voidaan todeta, että tulokset tukevat tunnettujen riskitekijöiden merkitystä D-vitamiinin puutoksessa ja tuovat lisää tietoa eri isomuotoihin vaikuttavista tekijöistä. Tutkimus antaa myös uusia näkemyksiä D-vitamiinin roolista lihavuuteen liittyvässä matala-asteisessa tulehduksessa. D-vitamiinin vaikutuksien tarkempi tunteminen on merkityksellistä myös kansanterveyden kannalta.

Changes in bone and mineral metabolism and the role of vitamin D in very low birth weight infants. Firstly, the aim of dissertation work was to estimate physiological parathyroid hormone (PTH) levels and their relationship with bone metabolism parameters in otherwise healthy preterm newborns with birth weight 1000-1500 g. Secondly, to evaluate vitamin D status in mothers and their very low birth weight infants (VLBW) at birth and at discharge with currently recommended supplementation of vitamin D. Thirdly, to compare clinical outcomes of VLBW infants with 25-hydroxy vitamin D [25(OH)D] levels ≤ and > 25 nmol/l in umbilical cord blood and finally to evaluate umbilical cord vitamin D as a risk factor for respiratory distress syndrome in preterm infants. It is a set of prospective observational studies involving immature newborns with birth weight below 1500 g. The parameters of mineral and bone metabolism were analysed in umbilical cord blood and newborn serum and urine during hospitalisation (PTH, 25-hydroxy vitamin D, S-Ca, S-P, ALP, U-Ca, U-P) and in pregnant women before delivery (25-hydroxy vitamin D). Bone mineralization was evaluated by bone densitometry. In a pilot study, from the total 134 examined serum samples for PTH levels the estimated reference range was 1.6 - 9.3 pmol/l. From the...