维生素A(也称视黄醇)可以在体内(主要是肝脏)大量贮存。一些研究指出,在正常代谢过程中肝脏贮存的A素释放进入血液的多少很大程度上取决于靶组织的需要,而不是肝脏A素贮存的多少。因此,尽管肝脏中A素的含量常常随着膳食情况发生很大变化,血液中A素的水平却在很大程度上维持相对稳定,所以仅仅测定血液中A素的含量,在一定程度上不能反映机体A素的营养状况。了解机体A素的贮存情况无疑对于积极预防A素缺乏有重要的实际意义。以往评价A素营养状况除了主要用血浆中维生素A含量水平外,尚有耐量曲线法,尿中A素代谢物排出量法,同位素稀释法。耐量曲线法采血次数多,受试者不易接受;尿代谢物法一方面收尿麻烦,影响因 Vitamin A (also known as retinol) can be stored in large quantities in the body (mainly the liver). Some studies indicate that how much of the liver’s stored A-release into the blood during normal metabolism depends largely on the needs of the target tissue rather than how much liver A is stored. Thus, while the level of A in the liver often varies greatly with dietary conditions, and the level of A in the blood remains relatively stable to a large extent, measuring the level of A in the blood alone can not, to some extent, Reflects the body’s A nutritional status. It is undoubtedly important to understand that the storage of A-A in the body is of positive significance for the prevention of A-deficiency. In the past evaluation of A nutritional status in addition to the main use of plasma levels of vitamin A, there is tolerance curve method, urinary metabolites of A metabolites, isotope dilution method. Endurance curve method, the number of blood tests, subjects are not easy to accept; urine metabolite method on the one hand, trouble urinating, the impact of