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* ACTIVATED PARTIAL THROMBOPLASTIN TIME

Mnemonic

PTT

Synonym

Partial Thromboplastin Time - APTT - PTT - aPTT

Specimen Collection Requirements

Collect

Whole Blood, light blue (3.2% Buffered Sodium Citrate) top tube

(View image for Supply Item Number - 238095)

Handling

See Coagulation Specimen Collection Guidelines. Due to the short stability of the specimen, whole blood specimen tubes must reach the testing department within 4 hours, otherwise submit frozen plasma aliquots. NOTE: Frost-free refrigerator freezers are not acceptable for frozen sample storage. If proper storage is unavailable at the collection site, freeze/store aliquots on dry ice.; Alternatively, send the patient to the nearest Legacy Hospital Outpatient Lab for sample collection/processing.

If submitting whole blood, transport at ambient temperature (15-25°C) in original unopened tube. If submitting frozen plasma aliquots, specimens must remain frozen (-20°C) during transport.

Preferred Volume

2.7 mL whole blood or two 1.0 mL frozen plasma aliquots

Minimum Volume

1.8 mL whole blood or one 1.0 mL frozen plasma aliquot

Transport

Whole Blood: Ambient (15-25°C) 

Plasma: Frozen, aliquot must remain frozen during storage and shipment

Rejection Criteria

Whole Blood Refrigerated (2-8°C)

Clotted samples; samples collected in containers other than 3.2% Buffered Sodium Citrate; tubes filled less than 90%; samples from patients with a Hematocrit greater than 55%; hemolyzed samples due to ex-vivo causes (i.e., difficult draw, poor sample draw); whole blood samples that were frozen before processing

Stability

WHOLE BLOOD: Ambient: 4 hours
PLASMA: Ambient: 4 hours; Frozen: (-20°C), 2 weeks, (-70°C), 6 months

NOTE - When sample is collected to monitor patient heparin therapy, stability times are shortened.
WHOLE BLOOD: Ambient: 1 hour
PLASMA: Ambient: 2 hours; Frozen: (-20°C), 2 weeks, (-70°C), 6 months

Testing Information

Performed

7 days/week

Reported

24 hours

Method

Clotting

Reference Values

Reference Values

Varies, see report.

Critical Values

>150 seconds

CPT Codes

85730

Last Updated: Monday, May 1, 2017 02:55:36 PM


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