Introdução - A concentração sérica de vitamina D pode variar em indivíduos de diferentes grupos etários e de diversas regiões geográficas e pode ser influenciada pela exposição solar, estação do ano, bem como pelos valores de IMC e paratormônio (PTH). A classificação utilizada para definir concentração sérica adequada de vitamina D refere valores de 25(OH)D acima de 30 ng/mL. Porém, essa classificação pode estar inapropriada para a população brasileira, devido às particularidades climáticas e alimentares. Objetivo - Verificar as concentrações séricas médias de 25(OH)D e PTH e sua relação com IMC, exposição solar e estação do ano e identificar os valores de corte da 25(OH)D associados à elevação do paratormônio (PTH) em adultos e idosos de amostra representativa da população do município de São Paulo. Métodos - Para esta dissertação foi desenvolvido um artigo original. O artigo original descreve o estudo transversal realizado com indivíduos do estudo ISA-Capital, estudo multicêntrico e de base populacional, onde foram investigados 589 indivíduos, de ambos os sexos, dos grupos etários: 20 a 59 (adultos) e 60 e mais (idosos). Foram coletadas amostras de sangue, para dosagens de 25(OH)D e PTH. Os indivíduos que aceitaram participar da coleta de sangue, também responderam um questionário sobre exposição solar. A análise estatística incluiu a curva ROC, testes t de Student, correlação e ANOVA. Os cálculos foram realizados pelo software SPSS versão 17.0. e p 0,05 foi considerado significante. Resultados - No artigo original observou-se idade média de 54,83 (19,21) anos, sendo 61,3 por cento do sexo feminino e 38,7 por cento do sexo masculino. A concentração sérica média de 25(OH)D foi 50,02 (22,69) ng/mL, já entre os grupos foi de 47,48 (23,03) (adultos) e 52,68 (22,06) ng/mL (idosos) havendo diferença significativa entre eles (p=0,005). Observou-se variação sazonal da concentração sérica de 25(OH)D e correlação positiva entre 25(OH)D e IMC (r = 0,114, p = 0,006). O novo valor de corte 55.8 ng/mL, determinado pela análise da curva ROC, encontrou 67,6 por cento dos indivíduos insuficientes de 25(OH)D e entre os grupos 72,1 por cento (adultos) e 62,8 por cento (idosos). Conclusão - Os resultados demonstram a presença de variação sazonal nas concentrações séricas de 25(OH)D no municipio de São Paulo. O ponto de corte proposto para nossa população indicou elevada prevalência de insuficiência de vitamina D. Portanto, se faz necessário políticas públicas de prevenção de insuficiência de vitamina D visando os efeitos benéficos na saúde e qualidade de vida desta população. / Introduction - The serum concentration of vitamin D may vary in individuals of different age groups and geographic regions and may be influenced by sun exposure, season and by BMI and parathyroid hormone (PTH). The classification widely used as a cut-off for appropriate vitamin D status refers serum 25 (OH) D above 30 ng/mL. However, this classification may be inappropriate for the Brazilian population, due to the particular food and the climate of our population. Objective - To determine the mean serum concentrations of 25(OH)D and PTH and correlate them with BMI, sunlight exposure and season and to identify the cutoff values of 25 (OH) D associated with elevation in PTH. Methods For this dissertation, one original article were developed. Original article describe cross-sectional study performed with subjects from the ISA Capital, multicenter population-based. We investigated 589 individuals were of both sexes, age groups: 20-59 (adults) and 60 (elderly). Blood samples for laboratory measurements of 25(OH)D and PTH were collected. Individuals, who agreed to participate in blood collection, also answered a questionnaire on sunlight exposure. Statistical analysis included ROC curve, Student t test, correlation tests, ANOVA. The calculations were performed by the software SPSS version 17.0. and p 0.05 was considered significant. Results - In the original article, the mean age of participants was 54.83 (19.21) years, 61.3 per cent female and 38.7 per cent were male. The mean serum 25 (OH) D was 50.02 (22.69) ng/mL, between the groups was 47.48 (23.03) (adults) and 52.68 (22.06) ng/ mL (elderly) and significant difference between them (p = 0.005). A seasonal variation in serum 25 (OH) D was observed and positive correlation between 25(OH)D and BMI (r = 0.114, p = 0.006). The new cutoff value 55.8 ng / mL, determined by ROC curve analysis found 67.6 per cent of subjects insufficient 25 (OH) D and between groups 72.1 per cent (adults) and 62.8 per cent (elderly). Conclusion - The results demonstrate the presence of seasonal variation in serum 25 (OH) D in the municipality of Sao Paulo. The cutoff point proposed for our population showed a high prevalence of insufficient vitamin D. Therefore, public policy is needed to prevent vitamin D insufficiency in order to beneficial effects on health and quality of life in this population.

Introduction Vitamin D status is an important public health issue due to the high prevalence of vitamin D insufficiency and deficiency, especially in high latitude areas. Furthermore, it has been reported to be associated with a number of diseases. In a previous umbrella review of meta-analyses of randomized clinical trials (RCTs) and of observational studies, it was found that plasma/ serum 25-hydroxyvitamin D (25(OH)D) or supplemental vitamin D has been linked to more than 130 unique health outcomes. However, the majority of the studies yielded conflicting results and no association was convincing. Aim and Objectives The aim of my PhD was to comprehensively explore the association between vitamin D and multiple outcomes. The specific objectives were to: 1) update the umbrella review of meta-analysis of observational studies or randomized controlled trials on associations between vitamin D and health outcomes published between 2014 and 2018; 2) conduct a systematic literature review of previous Mendelian Randomization studies on causal associations between vitamin D and all outcomes; 3) conduct a systematic literature review of published phenome wide association studies, summarizing the methods, results and predictors; 4) create a polygenic risk score of vitamin D related genetic variants, weighted by their effect estimates from the most recent genome wide association study; 5) encode phenotype groups based on electronic medical records of participants; 6) study the associations between vitamin D related SNPs and the whole spectrum of health outcomes, defined by electronic medical records utilising the UK Biobank study; 7) explore the causal effect of 25- hydroxyvitamin D level on health outcomes by applying novel instrumental variable methods. Methods First I updated the vitamin D umbrella review published in 2015, by summarizing the evidence from meta-analyses of observational studies and meta-analyses of RCTs published between 2014 and 2018. I also performed a systematic literature review of all previous Mendelian Randomizations studies on the effect of vitamin D on all health outcomes, as well as a systematic review of all published PheWAS studies and the methodology they applied. Then I conducted original data analysis in a large prospective population-based cohort, the UK Biobank, which includes more than 500,000 participants. A 25(OH)D genetic risk score (weighted sum score of 6 serum 25(OH)D-related SNPs: rs3755967, rs12785878, rs10741657, rs17216707, rs10745742 and rs8018720, as identified by the largest genome wide association study of 25(OH)D levels) was constructed to be used as the instrumental variable. I used a phenotyping algorithm to code the electronic medical records (EMR) of UK Biobank participants into 1853 distinct disease categories and I then ran the PheWAS analysis to test the associations between the 25(OH)D genetic risk score and 950 disease outcome groups (i.e. outcomes with more than 200 cases). For phenotypes found to show a statistically significant association with 25(OH)D levels in the PheWAS or phenotypes which were found to be convincing or highly suggestive in previous studies, I developed an extended case definition by incorporating self-reported data collected by UK Biobank baseline questionnaire and interview. The possible causal effect of vitamin D on those outcomes was then explored by the MR two-stage method, inverse variance weighted MR and Egger's regression, followed by sensitivity analyses. Results In the updated systematic literature review of meta-analyses of observational studies or RCTs, only studies on new outcomes which had not been covered by the previous umbrella review were included. A total of 95 meta-analyses met the inclusion criteria. Among the included studies there were 66 meta-analyses of observational studies, and 29 meta-analyses of RCTs. Eighty-five new outcomes were explored by meta-analyses of observational studies, and 59 new outcomes were covered by meta-analyses of RCTs. In the systematic review of published Mendelian Randomization studies on vitamin D, a total of 29 studies were included. A causal role of 25(OH)D level was supported by MR analysis for the following outcomes: type 2 diabetes, total adiponectin, diastolic blood pressure, risk of hypertension, multiple sclerosis, Alzheimer's disease, all-cause mortality, cancer mortality, mortality excluding cancer and cardiovascular events, ovarian cancer, HDL-cholesterol, triglycerides and cognitive functions. For the systematic literature review of published PheWAS studies and their methodology, a total of 45 studies were included. The processes for implementing a PheWAS study include the following steps: sample selection, predictor selection, phenotyping, statistical analysis and result interpretation. One of the main challenges is the definitions of the phenotypes (i.e., the method of binning participants into different phenotype groups). In the phenotyping step, an ICD curated phenotyping was widely used by previous PheWAS, which I also used in my own analysis. By applying the ICD curated phenotyping, 1853 phenotype groups were defined in the participants I used. In PheWAS, only phenotype groups with more than 200 cases were analysed (920 phenotypes). In the PheWAS, only associations between rs17216707 (CYP24A1) and "calculus of ureter" (beta = -0.219, se = 0.045, P = 1.14*10-6), "urinary calculus" (beta = -0.129, se = 0.027, P = 1.31*10-6), "alveolar and parietoalveolar pneumonopathy" (beta = 0.418, se = 0.101, P = 3.53*10-5) survived Bonferroni correction. Nine outcomes, including systolic blood pressure, diastolic blood pressure, body mass index, risk of hypertension, type 2 diabetes, ischemic heart disease, depression, non-vertebral fracture and all-cause mortality were explored in MR analyses. The MR analysis had more than 80% power for detecting a true odds ratio of 1.2 or larger for binary outcomes. None of explored outcomes were statistically significant. Results from multiple MR methods and sensitivity analyses were consistent. Discussion Vitamin D and its association with multiple outcomes has been widely studied. More than 230 outcomes have been linked with vitamin D by meta-analyses of observational studies and RCTs. On the contrary, evidence from Mendelian Randomization studies is lacking. In particular I identified only 20 existing MR studies and only 13 outcomes were suggested to be causally related to vitamin D. In the systematic literature review of previous PheWAS studies, I summarized the applied methods, predictors and results. Although phenotyping based on ICD codes provided good performance and was widely applied by previous PheWAS studies, phenotyping can be improved if lab data, imaging data and medical notes can be incorporated. Alternative algorithms, which takes advantage of deep learning and thus enable high precision phenotyping, needs to be developed. From the PheWAS analysis, the score of vitamin D related genetic variants was not statistically significantly associated with any of the 920 phenotypes tested. In the single variant analysis, only rs17216707 (CYP24A1) was shown to be associated with calculus outcomes statistically significantly. Previous studies reported associations between vitamin D and hypercalcemia, hypercalciuria, nephrolithiasis and nephrocalcinosis, may be due to the role of vitamin D in calcium homeostasis. In the MR analysis, I found no evidence of large to moderate (OR > 1.2) causal associations of vitamin D on a very wide range of health outcomes. These included SBP, DBP, hypertension, T2D, IHD, BMI, depression, non-vertebral fracture and allcause mortality which have previously been proposed to be influenced by low vitamin D levels. Further, even larger studies, probably involving the joint analysis of data from several large biobanks with future IVs that explain a higher proportion of the trait variance, will be required to exclude smaller causal effects which could have public health importance because of the high population prevalence of low vitamin D levels in some populations.

Introdução: Uma elevada prevalência de deficiência de vitamina D (DVD) em crianças tem sido observada em todo o mundo, mas poucos são os estudos com relação ao estado nutricional da vitamina D (VD) em lactentes saudáveis. A principal causa da deficiência em crianças saudáveis é o aleitamento materno sem suplementação e a falta ou insuficiência de exposição solar. Objetivos: Determinar as concentrações séricas de VD e verificar sua associação com concentrações de paratormônio (PTH), fosfatase alcalina (FA), cálcio (Ca), fósforo (P) e albumina e uso da suplementação de VD em lactentes saudáveis com idades entre >= 6 e <= 24 meses atendidos em duas Unidades Básicas de Saúde do município de Ribeirão Preto, SP, Brasil. Métodos: Estudo transversal, observacional e analítico em que foram determinadas as concentrações séricas de 25 (OH)D, PTH, FA, Ca, P e albumina de 155 lactentes saudáveis. Informações sobre exposição solar, aspectos sociodemográficos das mães e características clínico-nutricionais dos lactentes foram obtidas por entrevistas com os responsáveis dos lactentes. Concentrações séricas de 25(OH)D maiores que 20ng/ml foram consideradas adequadas, entre 12 a 20ng/ml insuficientes e < 12ng/ml deficientes. Resultados: Dez lactentes (6,5%, Intervalo de Confiança 95% 3,5-11,4) apresentaram insuficiência de VD e nenhum apresentou DVD. Nenhuma alteração nas concentrações séricas de P, Ca e albumina foram detectadas. Apenas um lactente apresentou aumento nas concentrações séricas de PTH e 35,5% dos lactentes apresentaram FA elevada, porém nenhum apresentou DVD ou insuficiência de VD. Não foram encontradas associações entre as concentrações séricas de 25(OH)D e as de FA, Ca e albumina. Houve associação entre concentrações séricas de 25(OH)D e PTH mesmo após ajuste para sexo, idade e Índice de Massa Corporal; também foi observada associação entre concentrações séricas de 25(OH)D e P apenas após o ajuste pelas covariáveis. Não foram verificadas associações entre insuficiência de VD, exposição solar e suplementação de VD. Conclusões: Uma baixa prevalência de concentrações insuficientes de 25(OH)D foi observada. Não foram encontradas associações entre as concentrações séricas de 25(OH)D e PTH, FA, Ca, P e albumina. Da mesma forma, não foram encontradas associações entre de concentrações séricas de 25(OH)D, exposição solar e suplementação de VD. / Introduction: A high prevalence of vitamin D deficiency (VDD) in children has been observed worldwide, but there are few studies on the nutritional status of vitamin D (VD) in healthy infants. The main cause of deficiency in healthy children is breastfeeding without supplementation and lack or insufficiency of sun exposure. Objective: To determine serum concentrations of VD and verify its association with parathyroid hormone (PTH) levels and use of VD supplementation in healthy infants aged >= 6 to <= 24 months attended at two Basic Health Units in Ribeirão Preto city, São Paulo, Brazil. Methods: A cross-sectional, observational and analytical study was performed in which were determined serum concentrations of 25 (OH) D, PTH, alkaline phosphatase (AP), calcium (Ca), phosphorus (P) and albumin of 155 healthy infants. Information of sun exposure, sociodemographic aspects of mothers and clinical and nutritional characteristics of infants were obtained through interviews with responsible for infants. Serum concentrations of 25(OH)D greater than 20ng / ml were considered adequate, between 12 to 20ng / ml insufficient and <12ng/ml, deficient. Results: Ten infants (6.5%, 95% Confidence Interval 3.5-11.4) presented VD insufficiency and none presented DVD. Only one infant had an increase in PTH serum concentrations and 35.5% of infants had high AP but none presented DVD or VD insufficiency. No changes in serum P, Ca and albumin concentrations were detected. No associations were found between serum concentrations of 25 (OH) D and AP, Ca and albumin. There was an association between serum concentrations of 25(OH)D and PTH even after adjusting for sex, age and body mass index; an association between serum concentrations of 25(OH)D and P was observed only after adjustment for covariates. There were no associations between VD insufficiency, sun exposure and VD supplementation. Conclusions: A low prevalence of insufficient concentrations of 25 (OH)D was observed. No associations were found between serum concentrations of 25 (OH)D and PTH, FA, Ca, P and albumin. Likewise, no associations were found between serum concentrations of 25 (OH)D, sun exposure and VD supplementation.

Background: The role of nutrients in mental health has recently been recognized and investigated. Vitamin D has been known to play a role in a wide range of diseases, such as bone, cardiovascular, and autoimmune diseases, and cancers. Recently, its role in cognitive function and mental health has been reported. Vitamin D receptor and hydroxylases have been mapped throughout the brain, suggesting a role for vitamin D in brain tissue. An inverse association between vitamin D and depression was observed in European epidemiologic studies. There is a paucity of data on the association between vitamin D concentrations and depression in the U.S. population. Objective: The objective of this study was to investigate the association between serum vitamin D concentrations and depression in a large, nationally representative sample survey, the third National Health and Nutrition Examination Survey 1988-1994 (NHANES III). Methods: The study sample included 7970 adults, ages 15-39 years, who completed the Diagnostic Interview Schedule for depression and had vitamin D concentrations measured. SAS and SUDAAN statistical software packages were used in data analysis. Multivariate logistic regression was used to estimate the likelihood of having depression in vitamin D deficient persons in relation to vitamin D sufficient persons, after taking several confounding variables into consideration. Significance was set at α < 0.05. Results: The prevalence of vitamin D deficiency was higher in women than in men (24 % vs. 15%), higher in African-Americans than in whites (60% vs. 10%), higher in people living in metropolitan rather than in rural areas (25% vs. 14%), and higher in subjects below the poverty threshold than in higher income subjects (29% vs. 14%). The prevalence of vitamin D deficiency increased as BMI increased. The diagnostic variables for depression did not show an association with vitamin D deficiency after adjusting for several confounding factors. However, subjects having a depressive episode at the time of the interview, were significantly more likely to exhibit vitamin D deficiencies (OR = 1.85; P = 0.0210). Conclusions: This is the first large epidemiologic study on the association between vitamin D and depression in a US representative sample survey. A significant positive association was found between subjects having an episode of depression and vitamin D deficiency. However, a causal relationship could not be established due to the cross-sectional nature of the study. Further studies need to investigate the mechanistic and causal relation between vitamin D and depression.

No description available.

Background: The role of nutrients in mental health has recently been recognized and investigated. Vitamin D has been known to play a role in a wide range of diseases, such as bone, cardiovascular, and autoimmune diseases, and cancers. Recently, its role in cognitive function and mental health has been reported. Vitamin D receptor and hydroxylases have been mapped throughout the brain, suggesting a role for vitamin D in brain tissue. An inverse association between vitamin D and depression was observed in European epidemiologic studies. There is a paucity of data on the association between vitamin D concentrations and depression in the U.S. population. Objective: The objective of this study was to investigate the association between serum vitamin D concentrations and depression in a large, nationally representative sample survey, the third National Health and Nutrition Examination Survey 1988-1994 (NHANES III). Methods: The study sample included 7970 adults, ages 15-39 years, who completed the Diagnostic Interview Schedule for depression and had vitamin D concentrations measured. SAS and SUDAAN statistical software packages were used in data analysis. Multivariate logistic regression was used to estimate the likelihood of having depression in vitamin D deficient persons in relation to vitamin D sufficient persons, after taking several confounding variables into consideration. Significance was set at α < 0.05. Results: The prevalence of vitamin D deficiency was higher in women than in men (24 % vs. 15%), higher in African-Americans than in whites (60% vs. 10%), higher in people living in metropolitan rather than in rural areas (25% vs. 14%), and higher in subjects below the poverty threshold than in higher income subjects (29% vs. 14%). The prevalence of vitamin D deficiency increased as BMI increased. The diagnostic variables for depression did not show an association with vitamin D deficiency after adjusting for several confounding factors. However, subjects having a depressive episode at the time of the interview, were significantly more likely to exhibit vitamin D deficiencies (OR = 1.85; P = 0.0210). Conclusions: This is the first large epidemiologic study on the association between vitamin D and depression in a US representative sample survey. A significant positive association was found between subjects having an episode of depression and vitamin D deficiency. However, a causal relationship could not be established due to the cross-sectional nature of the study. Further studies need to investigate the mechanistic and causal relation between vitamin D and depression.

Thesis (M.S.)--University of Missouri-Columbia, 2009. / Thesis advisor: Dr. Catherine Peterson. The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. "May 2009" Includes bibliographical references.

Thesis (M.F.C.S.)--Bowling Green State University, 2010. / Document formatted into pages; contains vi, 59 p. Includes bibliographical references.

Introdução: Portadores de fibrose cística têm uma susceptibilidade à deficiência de vitamina D devido à má absorção de nutrientes. Os estudos da prevalência de hipovitaminose D em pacientes com fibrose cística apresentam resultados extremamente variáveis e não há dados a respeito da população não pediátrica no Brasil. Objetivos: Avaliar a prevalência de hipovitaminose D em pacientes não pediátricos portadores de fibrose cística e os fatores associados com as concentrações séricas de 25-hidroxivitamina D. Metodologia: Realizado estudo transversal. A população em estudo foi composta por pacientes maiores que 16 anos acompanhados no Ambulatório de Fibrose Cística do Hospital de Clínicas de Porto Alegre. Foi avaliada a prevalência de deficiência de vitamina D, definida como 25-hidroxivitamina D < 30ng/mL, de acordo com a Cystic Fibrosis Foundation, bem como os fatores clínicos e laboratoriais associados com o valor sérico desta. Foram avaliados o estado nutricional e internações hospitalares. Foi realizada coleta de dados em prontuário, entrevista com os pacientes e colheita de sangue. As análises laboratoriais foram realizadas no Laboratório de Patologia Clínica do Hospital. Foram dosados os valores séricos de proteína C-reativa, cálcio, fosfato, magnésio, albumina, 25-hidroxivitamina D (método: quimiluminescência) e paratormônio (método: imunoensaio para PTH intacto). A função pulmonar foi avaliada por espirometria e escores clínicos e radiológicos. O nível de significância estatística foi estabelecido como P<0,05. Resultados: A prevalência de hipovitaminose D foi de 61,0%, com valores séricos de 25-hidroxivitamina D de 28,42±10,94 ng/mL. Os pacientes com insuficiência pancreática apresentaram uma tendência a ter concentrações mais altas de vitamina D. Dezesseis pacientes apresentavam doença pulmonar grave, com FEV1% do predito inferior a 40%. Após análise multivariada, índice de massa corporal e hospitalizações no último mês permaneceram significativamente associados negativamente aos valores séricos de 25-hidroxivitamina D. Conclusões: A prevalência de hipovitaminose D no presente estudo foi inferior a previamente relatada. A insuficiência de vitamina D continua sendo um problema nos pacientes com fibrose cística, mesmo naqueles recebendo suplementação. / Introduction: Cystic fibrosis patients have a susceptibility to vitamin D deficiency due to nutrient malabsorption. Prevalence studies of hypovitaminosis D in patients with cystic fibrosis have highly variable results and there is no data about the non pediatric population in Brazil. Objectives: To evaluate the prevalence of hypovitaminosis D in non pediactric cystic fibrosis patients and the factors associated with serum 25-hydroxyvitamin D levels. Methods: Cross-sectional study. The study population was composed of patients older than 16 years accompanied in the Cystic Fibrosis Ambulatory of the Hospital de Clínicas de Porto Alegre. We evaluated the prevalence of vitamin D deficiency defined as 25-hydroxyvitamin D < 30 ng/mL, as suggested recently by the Cystic Fibrosis Foundation, and clinical and laboratory factors associated with its serum levels. Nutritional status and hospital admissions were evaluated. Data was collected from medical records and interviews with patient, blood was collected. Laboratory analisys were performed at Clinical Pathology Laboratory of the Hospital. Serum C-reactive protein, calcium, phosphate, magnesium, albumin, 25-hydroxyvitamin D (method: chemiluminescence), and parathyroid hormone levels (method: sandwich immunoassay to intact PTH) were measured. Lung function was evaluated by spirometry and clinical and chest radiographic scores were assessed. Statistical significance level was set at P<0.05. Results: Prevalence of hypovitaminosis D was 61.0 %, with serum 25-hydroxyvitamin D levels of 28,42±10,94 ng/mL. Patients with pancreatic insufficiency had a trend to have higher vitamin D levels. Sixteen patients had severe lung disease with FEV1% predicted below 40%. After multivariable analysis, body mass index and hospitalization in the last month remained significantly associated negatively with serum 25-hydroxivitamin D levels. Conclusions: The prevalence of hypovitaminosis D in the present study was inferior to previously related. Vitamin D insufficiency is still a problem in cystic fibrosis patients, even in those receiving supplementation.

Introdução: Portadores de fibrose cística têm uma susceptibilidade à deficiência de vitamina D devido à má absorção de nutrientes. Os estudos da prevalência de hipovitaminose D em pacientes com fibrose cística apresentam resultados extremamente variáveis e não há dados a respeito da população não pediátrica no Brasil. Objetivos: Avaliar a prevalência de hipovitaminose D em pacientes não pediátricos portadores de fibrose cística e os fatores associados com as concentrações séricas de 25-hidroxivitamina D. Metodologia: Realizado estudo transversal. A população em estudo foi composta por pacientes maiores que 16 anos acompanhados no Ambulatório de Fibrose Cística do Hospital de Clínicas de Porto Alegre. Foi avaliada a prevalência de deficiência de vitamina D, definida como 25-hidroxivitamina D < 30ng/mL, de acordo com a Cystic Fibrosis Foundation, bem como os fatores clínicos e laboratoriais associados com o valor sérico desta. Foram avaliados o estado nutricional e internações hospitalares. Foi realizada coleta de dados em prontuário, entrevista com os pacientes e colheita de sangue. As análises laboratoriais foram realizadas no Laboratório de Patologia Clínica do Hospital. Foram dosados os valores séricos de proteína C-reativa, cálcio, fosfato, magnésio, albumina, 25-hidroxivitamina D (método: quimiluminescência) e paratormônio (método: imunoensaio para PTH intacto). A função pulmonar foi avaliada por espirometria e escores clínicos e radiológicos. O nível de significância estatística foi estabelecido como P<0,05. Resultados: A prevalência de hipovitaminose D foi de 61,0%, com valores séricos de 25-hidroxivitamina D de 28,42±10,94 ng/mL. Os pacientes com insuficiência pancreática apresentaram uma tendência a ter concentrações mais altas de vitamina D. Dezesseis pacientes apresentavam doença pulmonar grave, com FEV1% do predito inferior a 40%. Após análise multivariada, índice de massa corporal e hospitalizações no último mês permaneceram significativamente associados negativamente aos valores séricos de 25-hidroxivitamina D. Conclusões: A prevalência de hipovitaminose D no presente estudo foi inferior a previamente relatada. A insuficiência de vitamina D continua sendo um problema nos pacientes com fibrose cística, mesmo naqueles recebendo suplementação. / Introduction: Cystic fibrosis patients have a susceptibility to vitamin D deficiency due to nutrient malabsorption. Prevalence studies of hypovitaminosis D in patients with cystic fibrosis have highly variable results and there is no data about the non pediatric population in Brazil. Objectives: To evaluate the prevalence of hypovitaminosis D in non pediactric cystic fibrosis patients and the factors associated with serum 25-hydroxyvitamin D levels. Methods: Cross-sectional study. The study population was composed of patients older than 16 years accompanied in the Cystic Fibrosis Ambulatory of the Hospital de Clínicas de Porto Alegre. We evaluated the prevalence of vitamin D deficiency defined as 25-hydroxyvitamin D < 30 ng/mL, as suggested recently by the Cystic Fibrosis Foundation, and clinical and laboratory factors associated with its serum levels. Nutritional status and hospital admissions were evaluated. Data was collected from medical records and interviews with patient, blood was collected. Laboratory analisys were performed at Clinical Pathology Laboratory of the Hospital. Serum C-reactive protein, calcium, phosphate, magnesium, albumin, 25-hydroxyvitamin D (method: chemiluminescence), and parathyroid hormone levels (method: sandwich immunoassay to intact PTH) were measured. Lung function was evaluated by spirometry and clinical and chest radiographic scores were assessed. Statistical significance level was set at P<0.05. Results: Prevalence of hypovitaminosis D was 61.0 %, with serum 25-hydroxyvitamin D levels of 28,42±10,94 ng/mL. Patients with pancreatic insufficiency had a trend to have higher vitamin D levels. Sixteen patients had severe lung disease with FEV1% predicted below 40%. After multivariable analysis, body mass index and hospitalization in the last month remained significantly associated negatively with serum 25-hydroxivitamin D levels. Conclusions: The prevalence of hypovitaminosis D in the present study was inferior to previously related. Vitamin D insufficiency is still a problem in cystic fibrosis patients, even in those receiving supplementation.