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Test Code:
PT

Order Name:
Prothrombin Time (PT)

 
Useful For:
The test of Prothrombin time (PT) is the test to find the abnormality of blood clotting factor in Extrinsic pathway such as Factor II, V, VII and Factor X which can be guideline for diagnostic and monitoring the care of Oral anticoagulant
 
Methodology:
Clotting assay
 
Test List In Profile:
PT/INR
 
AliasesName:
PT
Pro Time
PT/INR
Protime INR
Prothrombin Time and International Normalized Ratio (PT/INR)
 
 
 
Test Code:
PT

Order Name:
Prothrombin Time (PT)

 
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:
PT

Order Name:
Prothrombin Time (PT)

 
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:
PT

Order Name:
Prothrombin Time (PT)

 
 
Clinical Information:
This assay is used to monitor oral anticoagulant therapy to maintain a patient in a safe therapeutic range.

In the absence of oral anticoagulant therapy, a prolonged prothrombin time indicates deficiency of 1 or more factors (I, II, V, VII, or X) or the presence of a coagulation inhibitor.

The prothrombin time is also reported as the INR (International Normalized Ratio), based on the ISI (International Sensitivity Index) assigned to the thromboplastin and coagulometer. This assay is used for monitoring "stable" oral anticoagulation.
 
Reference Value:
10.10 – 12.40 Second
Note: The reference range will change by reagent lot.
 
Interpretation:
  1. PT, which lasts longer than normal range, is found in patient who lacks or abnormal blood clotting in extrinsic pathway and common pathway such as factor VII, X, V, II and fibrinogen. Besides that, patient got something resisted toward blood clotting factor can make the PT result longer than normal as well.
  2. INR (International Normalized Ratio) INR = (Patient’s PT / Geometric mean of PT normal range)ISI Geometric mean calculated from 40 normal PT results which calculated by Microsoft exel. ISI (International Sensitivity Index) is attached in the insert sheet and different in each lot reagent. So, when the lot of reagent was changed, or changing the analyzer machine, ISI value should be changed for accurate INR value which is important when Anticoagulant therapy was givento patient, therapeutic range of INR level should be 2-3. In case INR is less than 2 that means physician gave less Anticoagulant which cannot dilute fibrin clot in the body. If INR value is more than 3, it means that Anticoagulant has been over taken and patient may got bleeding.
  3. The following condition and disease which can make PT’s value longer than normal: Liver failure (cirrhosis, hepatitis, jaundice), Vitamin K deficiency, Treatment with vitamin K antagonistsTreatment with preservation such as sodium warfarin (Coumadin), dicumeral, etc., Hemorrhagic disease of the newborn, Intestinal reabsorption disorder, Fibrinolysis and DIC.
 
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)