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Partial Thromboplastin Time (PTT, APTT)

Mnemonic:    [PTT]
Name:    Partial Thromboplastin Time (PTT, APTT)
Specimen:    2 mL plasma from a FULL sodium citrate Blue top tube. Allow tube to fill to proper capacity. Mix immediately by gentle inversion 4 times. Room temperature sample must be delivered to the CMMC hematology lab within one hour of collection. If the unspun sample cannot be delivered to the lab in that time period, the patient should be sent to the CMMC Outpatient Phlebotomy area for specimen collection.

A PTT can be added to an existing sample up to 4 hours after collection if it was spun within one hour of collection.
Reference Range:    0 - 1 month: 31.3 - 55.2 seconds
 1 month - adult: 22 - 35 seconds
Critical Range:    > 105 sec.
  Method:    Mechanical Clot Detection
Note:    Collection of Timed PTTs (Oct 18, 2013):
--When an inpatient has had a rate change in their IV infusion of agargatroban, a sample needs to be collected no earlier than 2 hours post change and no more than 2.5 hours past the rate change.
--These PTTs should be ordered as a Timed Study.
Processing Info:    The sample must be kept at room temperature prior to centrifugation. Any samples received separated must have been processed in a CAP approved calibrated and documented centrifuge to provide platelet poor plasma.