Lab Test : Prothrombin Time

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Alternate:Protime; PT; Pro Time
Phone:(937) 641-5100
SQ Code:PTX (PPTT if ordered with PTT)
Available:Daily, 24 hours
Turnaround:Routine: 3 hours, STAT: 30 minutes
Volume:1.3 mL
Container:Blue top tube (3.2% sodium citrate)
Temperature:Transport to the laboratory within 30 minutes of collection.
Rejection:Tube not filled to line, specimen clotted, specimen hemolyzed, specimen not received after 30 minutes collection.
Normal:11.8 - 16.4 seconds
Uses:Evaluation of extrinsic coagulation system. Aid in screening for congenital or acquired deficiencies of factors II, V, VII, and X. Aid in screening for dysfibrinogenemia, afibrinogenemia (complete) heparin effect, coumarin or warfarin effect, liver failure, disseminated intravascular coagulation (DIC) and in screening for vitamin K deficiency, monitor coumarin (oral anticoagulant) therapy.
Limitations:Because individual metabolism and the presence of other drugs significantly affect response to coumarin any therapeutic regimen must be carefully monitored. Barbiturates and oral contraceptives seem to inhibit coumarin, whereas salicylates, anabolic steroids, quinidine, disulfiram and many other agents enhance its anticoagulant effects. The PT is also affected by heparin and degree of the response is variable. To obtain a valid PT, it is necessary to wait until the heparin effect has disappeared (i.e. 2 hours after injection).
Method:Photo-optical endpoint

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