Gewebethromboplastin

Gewebethromboplastin, also known as tissue thromboplastin or simply thromboplastin, is a phospholipid‑protein complex derived from the cellular membranes of various tissues. It plays a central role in the extrinsic pathway of blood coagulation by providing a source of phospholipid surfaces and tissue factor (factor III), which together trigger the conversion of prothrombin to thrombin in the presence of calcium ions.

The preparation of Gewebethromboplastin typically involves homogenization of animal or human tissue—commonly brain, lung, or placenta—followed by extraction, purification, and lyophilisation. The resulting reagent is standardized for use in laboratory coagulation assays, most notably the prothrombin time (PT) test. In this assay, the addition of Gewebethromboplastin to citrated plasma initiates clot formation, allowing measurement of the time required for fibrin clot development. The PT value is used clinically to monitor oral anticoagulant therapy (e.g., warfarin) and to assess liver synthetic function, since many clotting factors are produced hepatically.

Gewebethromboplastin activity is expressed in International Units (IU) per millilitre, and commercial preparations are calibrated against reference standards established by the International Council for Standardization in Haematology. Variability in tissue source, extraction method, and storage conditions can affect reagent performance, prompting strict quality‑control procedures in diagnostic laboratories.

Beyond its diagnostic use, tissue factor derived from Gewebethromboplastin has been studied in experimental models of thrombosis and inflammation, where it contributes to the interplay between coagulation and immune responses. Research continues to explore recombinant and synthetic alternatives that may offer greater consistency and reduced reliance on animal tissues.