In Prothrombin time (PT) estimation, on addition of calcium and thromboplastin to platelet poor plasma. which of the following pathway is activated?
(A) Extrinsic (B) Intrinsic (C) Fibrinolysis (D) Common
(A) Ans. a. ExtrinsicIn Prothrombin time (PT) estimation, addition of calcium and thromboplastin to platelet poor plasma activates extrinsic pathway.The prothrombin time (PT) assay assesses the function of the proteins in the extrinsic pathway (factors VII, X,and .fibrinogen). In brief tissue factor, phospholipids, and calcium are added to plasma and the time for a fibrin clot to form is recorded.Prothrombin time (PT): This test assesses the extrinsic and common coagulation pathways. The clotting of plasma after addition of an exogenous source of tissue thromboplastin (e.g., brain extract) and Ca" ions is measured in seconds. A prolonged PT can result from deficiency or dysfunction of factor V, factor VII, factor X, prothrombin. or fibrinogen