People with low levels of vitamin D and its metabolites are at increased risk for osteoporotic fractures. We wished to ascertain levels of vitamin D in a representative sample of adult western Canadians, to help assess the level of risk. We evaluated the prevalence of vitamin D insufficiency, defined as 25-hydroxyvitamin D [25(OH)D] less than 40 nmol/L, and seasonal variations in 25(OH)D, parathyroid hormone and related biochemical indices in a community-dwelling population of healthy Canadians living in Calgary (latitude 51 degrees 07'N).
During calendar year 1999, we collected fasting overnight blood samples every 3 months from 60 men and 128 women (age range 27 to 89 years) who had volunteered to participate in another study. We used commercial radioimmunoassay kits to measure calciotrophic hormones and other biochemical indices. Regression models for longitudinal data were used to assess the effect of season and other potential predictors on individual parameters.
For a total of 64 participants (34%), vitamin D insufficiency, defined as 25(OH)D less than 40 nmol/L, was recorded at least once out of the 4 sampling times. After adjustment for age, body mass index and holiday travel, we observed the anticipated rise in serum 25(OH)D from a mean of 57.3 (standard deviation [SD] 21.3) nmol/L in the winter to 62.9 (SD 28.8) nmol/L in spring (p = 0.001) and 71.6 (SD 23.6) nmol/L in summer (p
Cites: N Engl J Med. 1997 Sep 4;337(10):670-69278463
Cites: J Am Geriatr Soc. 1997 May;45(5):598-6039158582
Cites: Osteoporos Int. 1997;7(5):439-439425501
Cites: J Bone Miner Res. 1998 Feb;13(2):168-749495509
Cites: J Bone Miner Res. 1998 Mar;13(3):475-829525348
Cites: Am J Clin Nutr. 1998 Jun;67(6):1232-69625098