Introduction
Prothrombin is also known as Factor II. The conversion of Factor X to Xa changes prothrombin into its active form, thrombin, which then accelerates the formation of fibrin. The level of the plasma prothrombin in the circulating blood decreases during its passage through the pulmonary capillaries (1). The bleeding tendency in acute chloroform intoxication is due to deficiencies in both plasma fibrinogen and plasma prothrombin (2). On the other hand, in severe Alzheimer's disease, prothrombin was localized within the wall and neuropil surrounding microvessels (3). It has been reported that plasma prothrombin level increases in sepsis patients (4) and in chronic gastrointestinal disorders (5).

Principle of the Assay
The AssayMax Human Prothrombin ELISA (Enzyme-Linked Immunosorbent Assay) kit is designed for detection of human prothrombin in plasma, milk, urine, and cell culture supernatants. This assay employs a quantitative sandwich enzyme immunoassay technique that measures human prothrombin in less than 4 hours. A monoclonal antibody specific for human prothrombin has been pre-coated onto a 96-well microplate with removable strips. Prothrombin in standards and samples is sandwiched by the immobilized antibody and biotinylated polyclonal antibody specific for human prothrombin, which is recognized by a streptavidin-peroxidase conjugate. All unbound material is then washed away and a peroxidase enzyme substrate is added. The color development is stopped and the intensity of the color is measured.