In this study, we analyzed the vitamin D status of Chinese children and adolescents aged 6-17y, and related risk factors (such as gender, region strata, ambient UVB level at area of residence, season, and outdoor time, etc.). Serum 25 hydroxyvitamin D [25(OH)D] was measured with a radioimmunoassay kit in 15 000 children and adolescent participants in Chinese national nutrition and health survey (CNNHS) 2010-2012. Age, gender, region type, ethnicity, outdoor time, vitamin D supplementation were recorded in unified design questionnaires. Season was recorded by the date of blood taken; location was divided into north and south by China's Qinling mountains and Huaihe river; and ambient ultraviolet B (UVB) radiation level was classified according to the corresponding dose of each participant living area from National Aeronautics and Space Administration data.
The aim of this study was to assess the vitamin D status and analyze risk factors for vitamin D inadequacy of Chinese children and adolescents aged 6-17y.