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Prothrombin Time (PT)

• Introduction
• Indications for Testing
• Detection Method
• Interpretation of Test Results
• Specimen Collection and Shipping Requirements
• Turn around Time
• Cost
• Request Hard Copy
• References

Introduction
Tissue thromboplastin is a lipoprotein found in many mammalian tissues. In the presence of calcium ions, thromboplastin is capable of activating the extrinsic pathway of coagulation. The Prothrombin Time (PT) Assay measures the time to convert fibrinogen to fibrin by the action of thrombin. The PT assay is sensitive to deficiencies in Factors II, V, VII and X. It can be prolonged by hereditary coagulation disorders, liver disease, vitamin K deficiency and oral anticoagulant therapy.

Indications for Testing
Individuals with a history of bleeding disorders or liver disease and those taking oral anticoagulation therapy should be tested with PT.

Detection Method
Calcium thromboplastin is used for the simultaneous determination of protrombin time and fibrinogen in human plasma. PT is measured by the IL TestTMPT-Fib.

Interpretation of Test Results
Normal expected values: 10.1 - 12.9 seconds.

Specimen Collection and Shipping Requirements

• Collect one (1) blue top tube.
• Spin, separate, freeze and ship in prepaid FedEx mailers overnight, next day morning.

Turn around Time
Processing of specimens begins immediately upon receipt at our facilities. Results are routinely available within 7 to 10 days and are initially faxed, then mailed to the requesting physician.

Cost
Included in our fees are specimen collection and shipping materials, all courier and shipping charges, telephone and written reports, and consultation with physicians. Please call (312) 274-1928 for pricing information.

Request Hard Copy

References
Quick AJ. Hemorrhagic diseases and thrombosis. In: Lea and Febiger. eds. Philadelphia, 1966.

Kelsey PR, Stevenson KJ, Pollan L. The diagnosis of lupus anticoagulants by the activated partial thromboplastin time. The central role of phosphatidylserine. Thromb Haem 1984;52:172-75.

Brandt IT, Barna LK, Triplett DA. Laboratory identification of lupus anticoagulants: results of the second international workshop for identification of lupus anticoagulants. Thromb Haem 1995;74:1597-1603.