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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. 

Specimen Handling DO NOT centrifuge. Keep at room temperature.
Must be tested within 4 hours of collection.
Additional Information  
Testing Location Hematology-All Sites
Testing Frequency Daily
Alternate Name(s) APTT, PTT, Partial Thromboplastin Time
Reference Interval
 ACH, DSC, FMC, RGH, PLC  25.0 - 35.0 seconds
 ACHC, CCHC, SMCHC, SCHC  25.0 – 34.0 seconds 

Click here for critical values.