AssayPro—Human Prealbumin ELIS

Introduction
Prealbumin (transthyretin) is a hepatic secretory protein thought to be important in the evaluation of nutritional deficiency and nutrition support (1). Prealbumin plays important physiological roles as a transporter of thyroxine and retinol-binding protein (2). Decreased prealbumin levels have been suggested to associate with malnutrition (3) and chronic kidney disease (4).

Principle of the Assay
The AssayMax Human Prealbumin ELISA kit is designed for detection of human prealbumin in plasma, serum, urine, saliva, milk, and cell culture supernatants. This assay employs a quantitative sandwich enzyme immunoassay technique that measures prealbumin in less than 4 hours. A polyclonal antibody specific for prealbumin has been pre-coated onto a microplate. Prealbumin in standards and samples is sandwiched by the immobilized antibody and biotinylated polyclonal antibody specific for prealbumin, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.

白蛋白（又称清蛋白，albumin，Alb）是由肝实质细胞合成，在血浆中的半寿期约为15-19天，是血浆中含量最多的蛋白质，占血浆总蛋白的40%-60%。其合成率虽然受食物中蛋白质含量的影响，但主要受血浆中水平调节，在肝细胞中没有储存，在所有细胞外液中都含有微量的白蛋白。关于白蛋白在肾小球中的滤过情况，一般认为在正常情况下其量甚微，约为血浆中白蛋白的0.04%，按此计算每天从肾小球滤过液中排出的白蛋白即可达3.6g，为终尿中蛋白质排出量的30-40倍，可见滤过液中多数白蛋白是可被肾小管重新吸收的。有实验证实白蛋白在近曲小管中吸收，在小管细胞中被溶酶体中的水解酶降解为小分子片段而进入血循环。白蛋白可以在不同组织中被细胞内吞而摄取，其氨基酸可被用为组织修补。