Test Catalog

Test ID: APTTP    
Activated Partial Thromboplastin 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 this test, the incubation of plasma sample with an optimal quantity of phospholipid, a negatively charged contact activator, and buffer initiates the activation of the intrinsic coagulation pathway. After incubation at 37 degrees C, calcium is added to trigger the coagulation process and the time required for clot formation is measured. The activated partial thromboplastin included in the SynthASil kit is a liquid buffered reagent that contains synthetic phospholipid for optimal platelet-like activity and highly defined nonsettling colloidal silica for optimal activation of the contact phase of coagulation.(Package insert: HemosIL SynthASil; IL ACL TOP Operator's Manual. Instrumentation Laboratory, Bedford, MA. R11. 06/2017)

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

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

24 hours

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