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Test Code:
APTT

Order Name:
Partial Thromboplastin Time (PTT)

 
Useful For:
The activated partial thromboplastin time (APTT) assay is used as a screening test to evaluate the overall integrity of the intrinsic/common coagulation pathway (factor XII, XI, X, IX, VIII, V,II, fibrinogen), Vitamin K deficiency) and to monitor patients on heparin therapy.
 
Methodology:
Clotting assay
 
AliasesName:
Activated Partial Thromboplastin Time (APTT)
 
 
 
Test Code:
APTT

Order Name:
Partial Thromboplastin Time (PTT)

 
Collection Specimen Or Container:
Blood/ Sodium citrate tube (Sodium Citrate 3.2% anticoagulant, Blue top) 3 mL, 1 tube
 
Specimen Testing Type:
Citrate plasma, minimum volume 0.5 mL
 
Sub Mission Container:
Plastic tube
 
Rejection Criteria:
Hemolysis: Hemoglobin >500 mg/dL
Lipemia: Triglyceride >1,000 mg/dL
Icterus: Bilirubin >26 mg/dL
Other: Clotted specimen will be rejected.
 
Specimen Stabillity:
Specimen Type Temperature Time
Whole blood, Sodium citrate Room temperature, 18oC to 24oC 4 hours
Plasma, Sodium citrate Refrigerated, 2oC to 8oC 4 hours
Room temperature, 18oC to 24oC 4 hours
Frozen, -20oC 2 weeks
Frozen, -70oC 1 year
 
 
 
Test Code:
APTT

Order Name:
Partial Thromboplastin Time (PTT)

 
Method detail:
Clotting assay
 
Schedule:
Tested Daily (24 hours)
 
Turnaround Time:
Collected specimen to report within 1 hour
 
Performing Location:
Hematology, Laboratory Department Tel. 17254
 
Specimen Retention Time:
14 days
 
 
 
Test Code:
APTT

Order Name:
Partial Thromboplastin Time (PTT)

 
 
Clinical Information:
TThe activated partial thromboplastin time (APTT) assay is used as a screening test to evaluate the overall integrity of the intrinsic/common coagulation pathway and to monitor patients on heparin therapy.

This test reflects the activities of most of the coagulation factors in the intrinsic and common procoagulant pathway, but not the extrinsic procoagulant pathway, which includes factor VII and tissue factor, nor the activity of factor XIII (fibrin stabilizing factor).

Effective November 2016, APTT will no longer be used as the primary method for therapeutic heparin monitoring, for that purpose, order the heparin anti-Xa assay HEPTP / Heparin Anti-Xa Assay, Plasma.
 
Reference Value:
25.00 – 36.60 Second
* The reference range will change by reagent lot
 
Interpretation:
Prolongation of the activated partial thromboplastin time (APTT) can occur as a result of deficiency of one or more coagulation factors (Intrinsic pathway and Common pathway ), or the presence of an inhibitor of coagulation such as heparin, Diphenylhydantoin, Warfarin, Nalaxone, a lupus anticoagulant, a nonspecific inhibitor such as a monoclonal immunoglobulin, or a specific coagulation factor inhibitor. Prolonged clotting times may also be observed in cases of fibrinogen deficiency, liver disease, and vitamin K deficiency.

Shortening of the APTT usually reflects either elevation of factor VIII activity in vivo that most often occurs in association with acute or chronic illness or inflammation, Estrogen, or spurious results associated with either difficult venipuncture and specimen collection or suboptimal specimen processing.
 
Clinical Reference:
  1. Manufacturer’s reagent package insert, SynthASil, HemosIL™, Instrumentation Laboratory Company - Bedford, MA 01730-2443 (USA), Instrumentation Laboratory SpA-V.le Monza 338 - 20128 Milano (Italy); 02/2016
  2. https://www.mayocliniclabs.com (Retrieved: 22 Jan 2019)