Activated Partial Thromboplastin Time

APTT, PTT, Partial Thromboplastin Time
Core Laboratory & Transfusion Medicine
Hematology
Blood
PTT

MSH Coagulation requisition form (MS 520)
The activated partial thromboplastin time (aPTT) is a screening procedure for deficiencies in coagulation factors of the intrinsic coagulation pathway, factors VIII, IX, XI, XII, Fletcher factor and Fitzgerald factor. Severe deficiencies of fibrinogen and factors II, V and X can also be detected by the aPTT. It is a useful and effective method for screening patients with a bleeding tendency, for evaluating the effect of therapy in procoagulant disorders and as the basis for several specific coagulation factor assay procedures. The aPTT is widely advocated as a test for monitoring and regulating heparin therapy. The presence of non-specific inhibitors, such as the lupus anticoagulant, may prolong the aPTT.
Plasma (3.2% Na Citrate)
Full draw
Light Blue citrate tube
Collection Containers – Tube Types
Send whole blood sample(s) at room temperature as soon as possible.
If specimens cannot be shipped immediately, centrifuge and separate plasma within 1 hour of collection, send frozen plasma on dry ice
Fridge: N/A
Room Temperature: 4 hours
Freezer: - 20 °C 2 weeks - 70 °C 12 months
Automated Coagulation Analyzer
24 hours, 7 days/week.
1 hour
2 hours
Adult: 18.5-29.9 sec
Full-term Infant at Birth: 31.3 – 54.3 sec
Premature Infant of 30 to 36 Weeks gestational age: 27.5 – 79.4 sec
Premature Infant of < 28 weeks gestational age: 53.7-139.3 sec In case of discrepancies, always interpret results using reference ranges as stated on laboratory reports and/or electronic patient chart.
416-586-4800 Extension 4688
Must indicate anticoagulant status