Comparison Of 25(OH)D Measurement Methods And Vitamin D Status Of Chinese Pregnant Women And Adolescents

Objective1 We attempted to identify a reliable and rapid 25(OH)D measurement method that is suitable for routine assays, particularly for large population-based surveys, such as the CHNNS.2 We evaluated the prevalence of vitamin D deficiency in a nationally representative sample of pregnant women in China. And we also want to predict the main risk factors for vitamin D deficiency in Chinese pregnant women.3 We evaluated the vitamin D status of Chinese primary school students and middle school students who lived in seven different latitude areas. And we try to find out the main risk factor of vitamin D deficiency in them.Methods1 Comparison of serum 25-hydroxyvitamin D measurementsWe compared a LC-MS/MS method using ESI to a LC-MS/MS method using APCI, in order to discover a reliable reference LC-MS/MS method of serum 25-hydroxyvitamin D measurements. We compared three 25-hydroxyvitamin enzyme immunoassays to the reference LC-MS/MS method. Then we compared the best one of the three 25-hydroxyvitamin enzyme immunoassays to radioimmunity assay, chemiluminescence immunoassay and electrochemiluminescence immunoassay. Methods compairson were included Spearman’s rank correlation coefficient, Passing-Balok regression, Bland-Altman plots and bias analysis. A quadratic weighted Kappa coefficient was designed to assess the level of agreement among different methods to identify vitamin D deficiency and insufficiency.2 Prevanlence and risk factors of vitamin D deficiency for Chinese pregnant womenData for the present analysis were derived from the China National Nutrition and Health Survey 2010-2013(CHNNS2010-2013).We select the participant by age and gestational age randomly.A total of 1985 healthy pregnant women participated. Serum 25(OH)D levels were measured by a 25-Hydroxy Vitamin EIA kit (Immunodiagnostic Systems Ltd, Boldon, UK). Possible predictors (age, gestational age, parity, smoking habit, vitamin D suppletion, gestational hypertension, gestational diabetes mellitus) for vitamin D deficiency were assessed by Spearman’s rank correlation and multiple logistic regressions.3 Vitamin D status of Chinese primary school students and middle school students who lived in different latitude areasWe invited 1546 primary school students and 1407 middle school students from 7 different latitude areas (Heilongjiang, Beijng, Zhejiang, Fujian, Guangdong, Guangxi, Hainan) into our study(More than 100 primary school students and 100 middle school students per each area). Demographic data (age, gender), vitamin D supplement, clothing style, daily outdoor times were recorded based on self-report.Daily Ca intake was assessed by the food frequency method. Serum 25(OH)D levels were measured by a 25-Hydroxy Vitamin EIA kit (Immunodiagnostic Systems Ltd, Boldon, UK). Possible predictors (daily Ca intake, vitamin D suppletion intake, exposure area, daily outdoor time, ambient UVB level, latitude) for vitamin D deficiency were evaluated by Spearman’s rank correlation and multiple logistic regressions.Results1 Comparison of serum 25-hydroxyvitamin D measurementsThe correlation between the IDS enzyme immunoassay and the reference LC-MS/MS methods, DiaSorin radioimmunity assay, IDS chemiluminescence immunoassay and Roche electrochemiluminescence immunoassay were in 0.651-0.981. The mean biases between the IDS enzyme immunoassay and comparison methods were in 2.9-9.0%. There were acceptable agreements between the IDS enzyme immunoassay and the comparison methods when using a cut-off-point of 20 ng/mL (weighted kappa value:0.487-0.709).2 Prevanlence and risk factors of vitamin D deficiency for Chinese pregnant womenMean serum 25(OH)D was 41.50±SD 16.41 (range 7.43-128.64) nmol/L. The prevalence of vitamin D deficiency was estimated to 49.4%.And serve vitamin D deficient was 25.5%. Vitamin D insufficiency was 21.1%.Only 4% of the participants had health vitamin D status. Vitamin D status of pregnant women was better with the lower latitude and higher ambient UVB level. In logistic regression analysis for all participants, the following factors were associated to vitamin D deficiency:younger age (P=0.026),latter gestational age (P=0.050), Hui ethnicity (P=0.027), season for collect serum (P＜0.001), ambient UVB of living area (P<0.001),latitude of living area(P<0.01) and vitamin D supplement (P=0.017). In logistic regression analysis for participants who were collecting serum in autumn, vitamin D deficiency was associated with Hui ethnicity (P=0.012), ambient UVB of living area (P＜0.001) and latitude of living area(P<0.001). In logistic regression analysis for participants who were collect serum in winter, vitamin D deficiency were associated to age (P=0.050), gestational age (P=0.035), pre-pregnancy BMI (P=0.019), ambient UVB of living area (P<0.001),latitude of living area (P<0.001)and vitamin D supplement (P=0.007).3 Vitamin D status of Chinese primary school students and middle school students who lived in different latitude areasVitamin D deficiency was less popular in boys than in girls (OR=0.662,.P=0.004 for primary school students; OR=0.616, P=0.001 for middle school students). Students living in high latitude areas had lower vitamin D level than students who living in lower latitude areas (P<0.01). Students living in higher ambient UVB level areas had higher vitamin D level than students who living in lower ambient UVB level areas (P<0.01). Primary school students had better vitamin D status than middle school students (P＜0.05), except Hainan and Fujian province.Consultions1 Comparison of serum 25-hydroxyvitamin D measurementsIDS enzyme immunoassay was given acceptable agreements with reference LC-MS/MS method, DiaSorin radioimmunity, IDS chemiluminescence immunoassay and Roche electrochemiluminescence immunoassay in 25(OH) D measurement. IDS enzyme immunoassay can be recommended for routine use by the Chinese population.2 Prevanlence and risk factors of vitamin D deficiency for Chinese pregnant womenVitamin D deficiency was highly prevalent in Chinese pregnant women, especially those residing in low ambient UVB level areas and high latitude area. The main risk factors for vitamin D deficiency in Chinese pregnant women were younger age, living in low ambient UVB areas, living in high latitude area, not using vitamin D supplement, Hui nationality women and cool season. Vitamin D health policymaking of Chinese pregnant women should pay more attention to the main risk factor of vitamin D deficiency.3 Vitamin D status of Chinese primary school students and middle school students who lived in different latitude areasVitamin D levels of Chinese primary school students and middle school students were affected by latitude and ambient UVB level of the living area. The primary school students had better vitamin D level than middle school students in the same area. This indicated Chinese middle school students had not been enough time to do outdoor activity.