PTT 1:2 Mix


Abbrev Code:PTT1T2   
Order Code:LAB3701Order Name:PTT Mixing Studies
Synonyms:Partial Thromboplastin Time 1:2 Mix; PTT Mix
Methodology:APTT assay of patient/normal plasma mixture at l:2 dilution
CPT Codes: 85730 x1, 85730 x1, 85525 x1, 85525 x1
Turnaround Time:Within 8 hours if received into the testing laboratory by 2 p.m. Testing performed 6 days per week. With pre-notification, STATs are done within 1 hour after receipt in the testing laboratory.
Special Instructions:A thrombin time will be performed. If thrombin time is greater than 19.0 seconds and the PTT-LA is greater than 45 seconds, a hepzyme will be performed (for an additional charge).
Associated Links:

Specimen Collection and Processing for Coagulation Specimens


Collection Instructions

Specimen:Blood
Optimal Volume:Two to three 3 mL tubes, each containing 2.7 mL blood; each filled to fill line on the tube.
Minimum\Peds Volume:One 3 mL tube containing 2.7 mL blood; filled to fill line on the tube.
Container:Blue Na Citrate, 3.2% - fill to fill line on tube
Collection Instructions:See link to Specimen Collection and Processing for Coagulation Specimens.
Causes for Rejection:Underfilled tubes, overfilled tubes, clotted specimens, specimens collected in 3.8% buffered citrate.


Processing and Shipping

Specimen Processing:
  • Process for Platelet Poor Plasma within 4 hours of collection.
  • Aliquot plasma, place clear tape around label, and freeze at -20C or on dry ice within 4 hours of collection.
  • If multiple tests are collected on 1 blue top, split each blue top into 2 aliquots. Minimum 0.5 mL per tube.
  • A maximum of 6 aliquots are needed per collection.
     
See link to Specimen Collection and Processing for Coagulation Specimens.
Shipping Instructions:
  • Ensure specimen is frozen before shipping.
  • Ship on dry ice, sample must remain frozen during shipping.
     
See link to Specimen Collection and Processing for Coagulation Specimens.
Test Performed at or Referral Lab UM Special Coag (K)  (UMMC East Bank)


Interpretive

Reference Range:
6 months and older:
Patient 31-45 seconds
1:2 Mix 31-45 seconds
Age specific reference ranges have not been established for the PTT in children less than 6 months of age. The PTT may be expected to be higher in neonates than in adults.
Use:To test for the presence of an inhibitor.


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