Mi Jie, Lin Liang-ming, Ma Guan-fu, Gu Xue, Liu Min, Cheng Hong, Hou Dong-qing, Tan Zang-wen, Liu Chun-yan
Department of Epidemiology, Capital Institute of Pediatrics, Beijing 100020, China.
Zhonghua Yu Fang Yi Xue Za Zhi. 2003 Nov;37(6):419-22.
To understand the prevalence of vitamin A deficiency (VAD) among children under six years of age in Tibet, China.
Totally, 1 257 children under six years of age were selected from two cities, two farming counties, two semi-farming counties and two livestock farming counties with stratified cluster sampling to asses VAD status in Tibet. Family information, children's feeding and disease history in the previous two weeks were collected by questionnaire. Blood specimen was collected from each child and serum was separated for detection of vitamin A concentration with microfluorescent spectrophotometry.
Totally, 1 257 children under six years of age were surveyed, with 635 boys, 622 girls, 862 aged over two years, and 98.5% of Tibet nationality. Six cases of night blindness and two cases of xerophthalmia were detected from them, with prevalence of clinical VAD of 0.96%. Eighteen of 1071 mothers with children under six years of age were found suffering from night blindness, accounting for 1.7%. Clinical cases of VAD both in children and mothers came from all four sampling strata. Average serum concentration of vitamin A and prevalence of subclinical VAD (serum vitamin A lower than or equal to 0.70 micromol/L) was 1.15 micromol/L and 5.4% and 1.12 micromol/L and 4.7% in cities and livestock farming counties, respectively, significantly higher than those in farming (1.04 micromol/L and 11.0%) and semi-farming counties (1.05 micromol/L and 12.3%), respectively, as compared to average levels of 1.09 micromol/L and 8.4% in the autonomous region as a whole. Prevalence of subclinical VAD in children under six months and those aged six to eleven months were 22.2% and 13.3%, respectively, significantly higher than those in children aged one year (8.5%), two to three years (5.4%) and four to five years (7.9%), respectively. There was also significant difference in serum level of vitamin A between children at varied ages, but no significant difference both in serum level of vitamin A and prevalence of subclinical VAD between gender was found.
In general, status of VAD in children of Tibet was milder than that at national level. But, moderate subclinical VAD in some areas, such as farming and semi-farming counties, did exist, so vitamin A supplementation aiming to children, especially those under one year of age, in those areas should be urged.
了解中国西藏6岁以下儿童维生素A缺乏症（VAD）的患病率。
采用分层整群抽样方法，从西藏的两个市、两个农业县、两个半农半牧县和两个牧业县选取1257名6岁以下儿童，评估西藏的VAD状况。通过问卷调查收集家庭信息、儿童喂养情况及前两周的疾病史。采集每个儿童的血样，分离血清，用微量荧光分光光度法检测维生素A浓度。
共调查1257名6岁以下儿童，其中男孩635名，女孩622名，2岁以上862名，藏族占98.5%。从中检出6例夜盲症和2例干眼症，临床VAD患病率为0.96%。在1071名6岁以下儿童的母亲中，有18名患有夜盲症，占1.7%。儿童和母亲的临床VAD病例均来自所有四个抽样层。城市和牧业县儿童维生素A平均血清浓度及亚临床VAD患病率（血清维生素A低于或等于0.70微摩尔/升）分别为1.15微摩尔/升和5.4%、1.12微摩尔/升和4.7%，显著高于农业县（1.04微摩尔/升和11.0%）和半农半牧县（1.05微摩尔/升和12.3%），而自治区整体平均水平为1.09微摩尔/升和8.4%。6个月以下和6至11个月儿童的亚临床VAD患病率分别为22.2%和13.3%，显著高于1岁儿童（8.5%）、2至3岁儿童（5.4%）和4至5岁儿童（7.9%）。不同年龄段儿童的维生素A血清水平也存在显著差异，但性别间维生素A血清水平及亚临床VAD患病率均无显著差异。
总体而言，西藏儿童VAD状况比全国水平较轻。但在一些地区，如农业县和半农半牧县，确实存在中度亚临床VAD，因此应在这些地区对儿童，尤其是1岁以下儿童，大力推行维生素A补充措施。
