title: Seasonal and inter-day variation in serum high-sensitivity C-reactive protein in Japanese male workers: a longitudinal study.
abstract: Although seasonal variation in high-sensitivity C-reactive protein (hsCRP) has been studied cross-sectionally and longitudinally, the results to date have been mixed. Here, to test seasonal variation in this compound with regard to within-subject, inter-day variation, we conducted a longitudinal follow-up study with repeated measurements in Japanese workers with low hsCRP. Blood samples were obtained from four male indoor daytime workers, who were aged 32-57 and commuted to offices in Kawasaki City, on six days within 2-wk windows in February and October, 2008. Serum hsCRP was measured using ultrasensitive latex-enhanced immunonephelometry. Among the subjects with detectable levels of hsCRP, individual median serum hsCRP levels were 38-74% higher in October than in February (p=0.03). This study identified the presence of a seasonal variation in the serum hsCRP level of Japanese workers with low hsCRP levels.
authors.affiliation: National Institute of Occupational Safety and Health, Nagao, Tama-ku, Kawasaki, Japan. itoh-hiroaki@umin.ac.jp
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Itoh
authors.forename: Ippei
authors.initials: I
authors.lastname: Mori
authors.forename: Yuki
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Syou
authors.initials: S
authors.lastname: Maki
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Ogawa
mesh_terms: D000328:Adult; D002097:C-Reactive Protein / Q000032:analysis* / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry / Q000379:methods; D012621:Seasons
chemical_list: D002097:C-Reactive Protein