ENVOY 500 AST Reagent Kit, reference Model/Catalog 55255, for Envoy 500. || Intended Use of the Product: Envoy 500 AST Reagent is for the quantitative in vitro diagnostic determination of aspartate aminotransferase (AST) in human serum and plasma using the Envoy 500 Chemistry System. || Aspartate aminotransferase (AST) measurements are used in the diagnosis and treatment of certain types of liver and heart diseases.