西藏自治区六岁以下儿童维生素A缺乏情况调查

目的 了解西藏自治区6岁以下儿童维生素A缺乏(VAD)情况。方法 采用分层整群随机抽样方法,将西藏分为城市、牧业县、农业县、半农半牧县4层,每层抽2个市或县进行调查。调查内容包括家庭一般状况、儿童喂养和疾病情况,收集儿童血清。血清维生素A(VA)含量检测采用微量荧光法。结果 共调查6岁以下儿童1257人,男635人,女622人,藏族占98．8％。2岁以上儿童836人,发现儿童夜盲症6例,结膜干燥症2例,儿童临床VAD患病率为0．96％。在1071名接受调查的母亲中,夜盲症18例(1．7％)。4类地区均发现有临床VAD病例。西藏儿童VA平均水平为1．09μmol／L,城市儿童(1．15μmol／L)和牧业县儿童(1．12μmol／L)显著高于农业县儿童(1．04μmol／L)和半农半牧县儿童(1．05μmol／L)。儿童亚临床VAD(血清VA≤0．70μmol／L)患病率：城市、牧业县、农业县和半农半牧县儿童分别为5．4％、4．7％、11．0％和12．3％,差异有显著性;0．5岁以下和0．5岁以上婴儿组亚临床VAD患病率分别为22．2％和13．3％,显著高于1岁以上各年龄组儿童(1岁为8．5％,2～3岁为5．4％,4～5岁为7．9％);男女儿童血清VA水平和亚临床VAD患病率的差异无显著性。结论 西藏儿童VAD情况较全国为轻,但农业县和半农半牧县属于中度亚临床VAD地区,需要对这些地区的儿童,特别是1岁以下的婴儿补充VA。

Prevalence of vitamin A deficiency in children under six years of age in Tibet, China

OBJECTIVE: To understand the prevalence of vitamin A deficiency (VAD) among children under six years of age in Tibet, China. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.