Vitamin D Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin D, including details on sources, melanin, benefits, deficiency, supplements, calcium absorption. | ||||||||
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Seasonal changes of serum 25-hydroxyvitamin D and intact parathyroid hormone levels in a normal Japanese population.Ono Y, Suzuki A, Kotake M, Zhang X, Nishiwaki-Yasuda K, Ishiwata Y, Imamura S, Nagata M, Takamoto S, Itoh M Division of Endocrinology and Metabolism, Department of Internal Medicine, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi, 470-1192, Japan. 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. Published 7 March 2005 in J Bone Miner Metab, 23(2): 147-51.
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