Source:http://linkedlifedata.com/resource/umls/id/C0030605
MSH: The time required for the appearance of FIBRIN strands following the mixing of PLASMA with phospholipid platelet substitute (e.g., crude cephalins, soybean phosphatides). It is a test of the intrinsic pathway (factors VIII, IX, XI, and XII) and the common pathway (fibrinogen, prothrombin, factors V and X) of BLOOD COAGULATION. It is used as a screening test and to monitor HEPARIN therapy.,NCI: A measurement of the length of time that it takes for clotting to occur when reagents are added to a plasma specimen. The test is partial due to the absence of tissue factor (Factor III) from the reaction mixture.,NCI: This is a measurement of the intrinsic pathway of coagulation. Significant deficiency in factors II, V, VIII, IX, X, XI, XII or anticoagulants will prolong PTT. (BioTech Life Science Dictionary)