| Objective 1. To investigate vitamin D nutritional status of infants in Nanjing city. 2. To investigate the utilization rate of vitamin D supplement and to investigate survey on infant vitamin D deficiency and influence of vitamin D supplement on serum 25-hydroxyvitamin D level. 3. To investigate ultrasound bone mineral density status of 0-3 years old infants and factors that affect their bone mineral density. 4.To investigate the relationship between serum 25-hydroxyvitamin D and quantitative ultrasound bone mineral density in 0-3 years old infants.Methods From November 2011 to September 2012, 378 0–3-year-old infants in Nanjing who were free from metabolic bone disease were recruited from a Children’s Health Care Center in Nanjing during their routine health checkups. A face-to-face interview with parents was conducted by a trained doctor using a structured questionnaire. These information included age, gender, infant feeding methods, parental education degrees,daily outdoor activities and supplementation of vitamin D. Blood samples from all participants were collected, and quantitatively determine the serum 25-(OH)D level of the blood samples with ELISA method. The sunlight 0mnisense ultrasound bone mineral density instrument were measured in infants of the tibia ultrasound transmission velocity( speed of sound, SOS)and Z value.Results1.The average level of serum 25-(OH)D was(67.2±23.0)nmol/L. The level of serum 25-(OH)D fluctuate with increasing of age. Vitamin D deficiency[25-(OH)D<50 nmol/L] was observed in 21.16 % of these infants. 2. The utilization rate of vitamin D supplement was 79.1% in this study. During different ages,infant feeding methods,birth weights and parental education degrees, the utilization rate of vitamin D supplement were statistically significantly different. The multi-factors Logistic regression analysis suggested that supplementation of vitamin D was significantly associated with ages,feeding methods and maternal level of education. The level of serum 25-(OH)D after vitamin D supplementation was significantly higher than the non-supplement group,and take vitamin D 500 IU one day can make the serum 25(OH)D level to reach the highest and the lowest rate in vitamin D deficiency. 3. The incidence of abnormal BMD of infants was 32.8%, BMD was significantiy increased with increasing of age and the incidence of abnormal BMD was decreased. During different genders, BMD had no statistical significance. The multi-factors Logistic regression analysis suggested that BMD was significantly associated with age and the outdoor activities time. 4.The concentration of serum 25-(OH)D in low BMD group was(60.4±15.3)nmol/L and lesser than that in normal group(66.8±22.0) nmol/L(P>0.05). And there were 19.35% and1 22.05% of infants whose serum 25(OH)D level were ≤50nmol/L in low BMD group and normal group(P>0.05).The further linear correlation analysis showed that the serum 25(OH)D was not positively linear correlated with BMD of infants(r=0.16,P>0.05). ResultsConclusions 1.Vitamin D deficiency is observed in 21.16 % of these infants in our study. Especially in the 0-6 and 13-36 months groups, vitamin D deficiency are more outstanding and should be paid more attention. 2.The utilization rate of vitamin D supplement is 79.1% in this study. Supplementation of vitamin D 500 IU daily can improve the serum 25(OH)D level and make it achieve a better state.It suggested that we should simultaneously pay attention to the utilization rate of vitamin D supplements and the dose-dependent response. 3.Abnormal BMD of infants is widespread in nanjing city, multi-factors such as age,nutritional status,outdoor activities time affect BMD measurements when it is as an effect indicator of bone health.And we should test the BMD of infants in a regular basis. 4.We don’t find that vitamin D status of infants is linear correlated with BMD in our study,so whether or not the quantitative ultrasound BMD value can be an indicator for evaluation vitamin D status in infants still needs further research. |
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