title: A seasonal difference in serum 25-hydroxyvitamin D3 in a Finnish population.
abstract: A chromatographic assay procedure for the analysis of 25-hydroxyvitamin D3 [25(OH)D3] in human serum is described. The procedure involves methanol/chloroform extraction of serum lipids followed by separation of the vitamin D metabolites and purification from interfering contaminents by chromatography on Sephadex LH-20 and by high-pressure liquid chromatography. 25(OH)D3 is quantitated by uv detection, and its peak height compared with those of standards. Values in normal human serum samples taken in July-August and January-February are: 33.0 +/- 13.6 ng/ml (82.5 +/- 34.1 nmol/1) and 14.5 +/- 12.2 ng/ml (36.3 +/- 30.5 nmol/1) (means +/- SD), respectively (p less than 0.001). The summer values are somewhat lower in the elderly subjects as compared to younger ones, but a seasonal difference was observed in both groups. This difference may be due to a relatively low vitamin D intake and a limited sun exposure.
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002853:Chromatography, Liquid / Q000379:methods*; D005260:Female; D005387:Finland; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012621:Seasons
chemical_list: D006887:Hydroxycholecalciferols