title: Vitamin D status in a sunny country: where has the sun gone?
abstract: OBJECTIVE
  Hypovitaminosis D [serum 25 vitamin D<30 ng/ml] is related to the development of metabolic bone disease and greater risk of chronic illnesses. However, it is frequently under-diagnosed, mainly in countries where UV radiation is abundant. We prospectively determined the prevalence and the predictors of serum 25 vitamin D (s25(OH)D) in a healthy Brazilian population after the winter and after the summer.
  
  
  METHODS
  603 (118M and 485F) healthy Brazilian volunteers aged 18-90 years from a universitary hospital were selected after the winter of 2006. From the initial sample, 209 volunteers (31M and 178F) accepted to participate in a second health check after the subsequent summer.
  
  
  RESULTS
  After the winter, median s25(OH)D was 21.4 ng/mL and 77.4% of the population presented hypovitaminosis D. s25(OH)D was significantly related to age, BMI, PTH and race. In multivariate linear regression analysis, s25(OH)D was significantly and independently dependent on age, glycemia and skin color. Significant increase in s25(OH)D was verified after summer [10.6 (3.7-19.3 ng/ml); p<0.001] and this improvement was dependent on age. We also observed a significant decrease in hyperparathyroidism prevalence (20.8% vs. 4.9%; P<0.0001).
  
  
  CONCLUSIONS
  In São Paulo, at the end of winter, we observed a high prevalence of hypovitaminosis D and secondary hyperparathyroidism in healthy adults. s25(OH)D was dependent on age and skin color. After summer, we observed a decrease in the prevalence of hypovitaminosis D. This unexpected finding emphasizes the need for a strong recommendation to monitor s25(OH)D, even in a sunny country such as Brazil.
authors.affiliation: Nephrology Department, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Marianna D
authors.initials: MD
authors.lastname: Unger
authors.forename: Lilian
authors.initials: L
authors.lastname: Cuppari
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Titan
authors.forename: Maria Cláudia T
authors.initials: MC
authors.lastname: Magalhães
authors.forename: Ana L
authors.initials: AL
authors.lastname: Sassaki
authors.forename: Luciene M
authors.initials: LM
authors.lastname: dos Reis
authors.forename: Vanda
authors.initials: V
authors.lastname: Jorgetti
authors.forename: Rosa Maria Affonso
authors.initials: RM
authors.lastname: Moysés
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil / Q000453:epidemiology; D005006:Ethnicity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000150:complications / Q000503:physiopathology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010281:Parathyroid Hormone / Q000097:blood / Q000172:deficiency; D015995:Prevalence; D011446:Prospective Studies; D012621:Seasons; D013472:Sunlight; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000150:complications / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D