Yale New Haven Hospital

Department of Laboratory Medicine
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Partial thromboplastin time

Lab Section: 

Coagulation

 

Lab Location: 

Main Lab

Test ID: 

LAB2315

 

Synonyms:

PTT

 

Methodology: 

Clotting

Schedule: 

Sun-Sat

Reported: 

Routine: 2.5 hours; Stat: 1.5 hours

Specimen Requirements: 

Collection: 2.7 mL Blood in a Blue Top Tube.
Pediatric volume: 2.7 mL.
Tube must be full.
Transport: Whole blood may be transported at ambient or refrigerated temperature. Separated plasma, not yet frozen, may be transported at refrigerated temperature, while frozen plasma should be sent on dry ice to prevent thawing in transit..
Unacceptable conditions: QNS; Overfilled; clotted
Stability: 4 Hours from collection time.

 

Notes: 

Clinical Indications: General screening for deficiencies of the intrinsic and/or common coagulation pathway factors; monitoring heparin therapy; screening test for lupus anticoagulant.

For a patient on unfractionated heparin, without factor deficiency or another anticoagulant present, a PTT of approximately 50-90 seconds corresponds to a therapeutic range of 0.3-0.7 U/mL anti-Xa activity.

Reference Interval: 

Age Limit

Sex

Normal Range

Units

0 - 999 Years

Any

22.9-31.3

seconds

 

CPT Code(s): 

85730

Last Changed: 

09/04/2016 14:59:21

Last Reviewed: 

8/15/2017 10:15 AM

                                      Last Changed  7/3/2018 10:31 AM