title: Seasonal changes of serum 25-hydroxyvitamin D and intact parathyroid hormone levels in a normal Japanese population.
abstract: We conducted an observational study in order to assess the prevalence of hypovitaminosis D and its seasonal changes, in the Tokai area (N35.3 E137.0), in 197 normal subjects in Japan. The mean serum 25-hydroxyvitamin D (25-OHD) level measured by direct radioimmunoassay (RIA) was lowest at the end of winter, and highest at the end of summer (15.1+/-7.1 ng/ml in March; 21.5+/-5.5 ng/ml in June; 31.6+/-5.6 ng/ml in September; 23.1+/-5.3 ng/ml in December; mean+/-SD). The prevalence of hypovitaminosis D (<20 ng/ml) was 86.7%, 33.4%, 1.0%, and 26.0% in March, June, September, and December, respectively. Mean plasma intact parathyroid hormone (iPTH) concentration was lowest at the end of summer and highest at the end of winter (28.2+/-9.3 pg/ml in March; 21.7+/-7.0 pg/ml in June; 19.8+/-6.9 pg/ml in September; and 25.7+/-9.2 pg/ml in December; mean+/-SD). Serum 25-OHD was inversely associated with iPTH (coefficient, -0.223; r=0.251; P<0.001). Serum 25-OHD levels were higher in men than in women. The serum 25-OHD level was positively associated with age, body weight, and body mass index, but not with body fat content. These results suggest a high prevalence of hypovitaminosis D associated with elevation of iPTH in Japan, in winter, even in a sunny area.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi, 470-1192, Japan.
authors.forename: Yasunaga
authors.initials: Y
authors.lastname: Ono
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.forename: Motoko
authors.initials: M
authors.lastname: Kotake
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.forename: Keiko
authors.initials: K
authors.lastname: Nishiwaki-Yasuda
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ishiwata
authors.forename: Shigeo
authors.initials: S
authors.lastname: Imamura
authors.forename: Mutsuko
authors.initials: M
authors.lastname: Nagata
authors.forename: Satoru
authors.initials: S
authors.lastname: Takamoto
authors.forename: Mitsuyasu
authors.initials: M
authors.lastname: Itoh
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D012016:Reference Values; D012044:Regression Analysis; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood*; D014808:Vitamin D Deficiency / Q000453:epidemiology
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D