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Test Code:
PTM

Order Name:
PT & PT Mixing Study

 
Useful For:
Screening test to detect a deficiency of 1 or more of the clotting factors of the extrinsic coagulation system (I, II, V, VII, X) due to hereditary deficiency or acquired conditions such as liver disease, vitamin K deficiency, or a specific factor inhibitor.
 
Methodology:
Clotting assay
 
AliasesName:
Prothrombin Time Mix 1:1
 
 
 
Test Code:
PTM

Order Name:
PT & PT Mixing Study

 
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 >30 mg/dL
Other: Clotted specimen will be rejected.
 
Specimen Stabillity:
Specimen Type Temperature Time
Whole Blood, Sodium citrate Room temperature, 18oC to 25oC 4 hours
Plasma, Sodium citrate Room temperature, 18oC to 25oC 4 hours
Refrigerated, 2oC to 8oC 4 hours
Frozen, -20oC 2 weeks
Frozen, -70oC 1 year
 
 
 
Test Code:
PTM

Order Name:
PT & PT Mixing Study

 
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:
PTM

Order Name:
PT & PT Mixing Study

 
 
Clinical Information:
The prothrombin time (PT) mix is only performed when the PT is abnormally prolonged. Please refer to test PTC / Prothrombin Time (PT), Plasma for an interpretation of results.
 
Interpretation:
PT mixing study, using equal volume patient and normal pool plasma, may be performed on specimens with a prolonged PT to assist in differentiating coagulation factor deficiencies from coagulation inhibitors. Correction of the PT mix to within the normal reference range usually indicates a coagulation factor deficiency (normal plasma in the mixture ensures at least 50% activity of all coagulation factors). If the prolonged PT is due to an inhibitor (specific coagulation factor inhibitor, lupus anticoagulant, heparin, etc.), the PT mix typically fails to correct a prolonged PT. However, the presence of a weak inhibitor may be missed by the PT mixing study.

Accurate interpretation of both PT and PT mixing study results may often require additional testing. For example, the thrombin time (TT) test is helpful for identifying or excluding the presence of heparin, the platelet neutralization procedure (PNP, using a modified APTT method) for identifying or excluding lupus anticoagulant, the activated partial thromboplastin (APTT) and dilute Russell's viper venom time (DRVVT) for further assessment of the common procoagulant pathway, and coagulation factor assays to detect and identify deficient or abnormal factors. These assays are available as components of reflexive and interpretive testing panels in the Special Coagulation Laboratory (eg, PROCT / Prolonged Clot Time Profile).
 
Clinical Reference:
  1. Manufacturer’s reagent package insert , RecombiPlasTin 2G,HemosILTM, Instrumentation Laboratory Company - Bedford, MA 01730-2443 (USA), Instrumentation Laboratory SpA - V.le Monza 338 - 20128 Milano (Italy) ; 09/2016
  2. https://www.mayocliniclabs.com (Retrieved: 22 Jan 2019)