Osteoporosis International

, Volume 16, Issue 12, pp 1649–1654

Influence of ultraviolet radiation on the production of 25 hydroxyvitamin D in the elderly population in the city of São Paulo (23 o 34’S), Brazil

  • Gabriela Luporini Saraiva
  • Maysa Seabra Cendoroglo
  • Luiz Roberto Ramos
  • Lara Miguel Quirino Araújo
  • José Gilberto H. Vieira
  • Ilda Kunii
  • Lillian F. Hayashi
  • Marcelo de Paula Corrêa
  • Marise Lazaretti-Castro
Original Article

DOI: 10.1007/s00198-005-1895-3

Cite this article as:
Saraiva, G.L., Cendoroglo, M.S., Ramos, L.R. et al. Osteoporos Int (2005) 16: 1649. doi:10.1007/s00198-005-1895-3

Abstract

The lack of vitamin D is a major changeable factor involved in the pathophysiology of osteoporosis. Since the major source for this hormone is its cutaneous synthesis via ultraviolet radiation (UVR), we studied the serum level of 25-hydroxyvitamin D (25OHD) in 250 free-living elderly people (79.1 years old) from a subtropical region according to the UVR incidence and its correlations with parathormone (PTH) and ionized calcium. UVR and 25OHD differed according to the season of the year (P<0.001), with greater radiation in the summer and less in the winter, whereas the 25OHD peak and nadir occurred in autumn and spring, respectively. The highest 25OHD mean was 67.2 nmol/l, and the lowest was 29.1 nmol/l corresponding, respectively, to the measure of the month subsequent to the one of most and least sunlight incidence. Clustered by season, the correlation between UVR and 25OHD for the following seasons was r =0.98 and between the PTH and 25OHD of corresponding seasons, r =–0.95. Vitamin D deficiency occurred in 15.4% of patients, insufficiency in 41.9% and secondary hyperparathyroidism in 55%. In conclusion, we found a seasonal variation in 25OHD levels that strongly correlated with the PTH levels when separated by the seasons of the year. The 25OHD levels correlated with the UVR of the previous quarter, requiring no less than 30 days for serum changes arising from exposure to or deprivation of UVR to be observed. The prevalence of vitamin D deficiency/insufficiency found was greater than expected, even when compared to countries exposed to less solar irradiation. Thus, measures to encourage greater sun exposure and food enrichment policies should also be considered.

Keywords

Elderly Prevalence Solar radiation Vitamin D 

Copyright information

© International Osteoporosis Foundation and National Osteoporosis Foundation 2005

Authors and Affiliations

  • Gabriela Luporini Saraiva
    • 1
  • Maysa Seabra Cendoroglo
    • 2
  • Luiz Roberto Ramos
    • 2
  • Lara Miguel Quirino Araújo
    • 2
  • José Gilberto H. Vieira
    • 1
  • Ilda Kunii
    • 1
  • Lillian F. Hayashi
    • 1
  • Marcelo de Paula Corrêa
    • 3
  • Marise Lazaretti-Castro
    • 1
  1. 1.Division of EndocrinologyPaulista Medical School of the Federal University of São PauloSão PauloBrazil
  2. 2.Division of GeriatricsPaulista Medical School of the Federal University of São PauloSão PauloBrazil
  3. 3.Division of Satellites and Environmental SystemsCenter of Climate Prevision, National Space Research Institute (CPTEC/INPE)São PauloBrazil