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Activated Partial Thromboplastin Time

Source Blood
Mnemonic PTT
Specimen Requirements

Adult:
1 x 2.7 mL blue top sodium citrate plastic tube is preferred. 4.5 mL blue top sodium citrate glass tube is also acceptable.

Pediatric:
1 x 2.7 or 1.8 mL short-draw blue top sodium citrate tube

Whole blood. VENOUS COLLECTION ONLY. Skin puncture (capillary) collection is not acceptable.

It is important to fill tube to maximum draw. Mix well.

Indicate collection time on tube.

Both APTT and prothrombin time/INR can be collected on one blue top tube.

When using a winged blood collection set (butterfly needle) a discard tube must be used to remove the air in the tubing, if only a citrate tube is drawn or is the first tube drawn. 

Adjusted PTT:
For patients with high hematocrit results, an adjusted citrate tube may be required for collection; the amount of anticoagulant in the tube has been modified to be specific for the patient.
CLS collection of adjusted PTT:
- If 'adjusted PTT' is indicated, hematology may provide an adjusted citrate tube or request a CBC and PTT collection. An EDTA sample is required to calculate the anticoagulant ratio. If CBC is not requested, order and collect an extra EDTA tube.
- An adjusted citrate tube may be provided for recollection of the PTT after the CBC is completed.
- The adjusted citrate tube will be clearly marked with a 'fill line'; the tube must be filled to that line to maintain the correct anticoagulant/sample ratio.
- The adjusted tube does not have a vacuum and must be collected using a syringe. Remove cap from PTT tube, remove needle from syringe and slowly dispense blood down the inside of the tube, filling to the indicated fill line.
- Keep collected tubes together with an elastic band and place in a separate bag labelled "Adjusted PTT". Deliver directly to Hematology.

Specimen Handling DO NOT centrifuge until tube arrives at testing site. Keep at room temperature.
Must arrive within 3.5 hours of collection.
Additional Information  
Testing Location Hematology-All Sites
Rural: CRL
Testing Frequency Daily
Alternate Name(s) APTT, APTT-FS, Partial Thromboplastin Time, PTT, PTT Actin FS, PTT-FS
Reference Interval

 ACH, DSC, FMC, PLC, RGH, SHC,
 ACHC, CCHC, SCHC, SMCHC,
 
CMGH, HRH, SDHS

  26.0 - 36.0 seconds  

 BMSH, CLH, DDHS, OGH, OHWC,
 VCH  

25.0 - 34.0 seconds


Click here for critical values.