Test Catalog

Test ID: PTTP    
Prothrombin Time, Plasma

Method Description Describes how the test is performed and provides a method-specific reference

Coagulometric (turbidimetric) clot detection is based on the principle that light passing through a medium in which fibrinogen is converted to fibrin is absorbed by the fibrin strands. Light at 671 nm is transmitted through a sample onto a photodetector, which is positioned 180 degrees to the source. Light absorption increases as fibrin clot formation progresses. Consequently, light transmittance through the sample continuously decreases and is measured by the photodetector. The corresponding electrical signal output from the photodetector changes according to the detected light. The signal output is processed via software through a series of algorithms to determine the clot point.


In the prothrombin time (PT) test, the addition of the tissue thromboplastin (RecombiPlasTin 2G reagent) to the patient plasma in the presence of calcium ions initiates the activation of the extrinsic pathway. This results ultimately in the conversion of fibrinogen to fibrin, with formation of a solid gel. The time required for clot formation is measured. The thromboplastin reagent included in the RecombiPlasTin 2G kit, after reconstitution with the RecombiPlasTin 2G Diluent, is a liposomal preparation that contains human recombinant tissue factor (RTF) relipidated in a synthetic phospholipid blend and combined with calcium chloride, buffer and a preservative.(Package insert: HemosIL RecombiPlasTin 2G; IL ACL TOP Operator's Manual. Instrument Laboratory, Bedford, MA. R10. 03/2019)


This PT test is performed with a sensitive thromboplastin (ISI 1.0 +/- 0.05), containing phospholipid and recombinant human tissue factor.

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

Monday through Sunday; Continuously

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

Same day/1 day

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Clinic Laboratories until the release of the test result

Same day/1 day

Performing Laboratory Location Indicates the location of the laboratory that performs the test