Pathology

Test & Collection Guide

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Activated Partial Thromboplastin Time

Alternate names:

APTT, KPTT

Laboratory:

Coagulation

Test Code:

APTT

Specimen types:

Plasma

Container types:

Sodium Citrate

Collection Instructions:

Transport specimen at Room Temperature to lab
Samples found to have clots cannot be tested

Specimens from APTT assays on nonheparinized patients are kept at room temperature and centrifuged with with plasma remaining on top of cells in an unopened tube should be tested within 4 hours of the collection time.

Specimens from APTT assays suspected to contain unfractionated heparin are kept at room temperature and centrifuged within 1 hour of collection and the plasma tested within 4 hours of the collection time. If agitation is likely after centrifugation the plasma should be removed from the cells.

Notes:

Tube filled to label marker and mixed by inversion.

Frequency:

Daily

Result Turnaround Time:

4 hours

Reference Interval:

Non-heparin:	25-35 seconds
IV heparin therapeutic ranges:	60-90 seconds

Please note updated reference ranges from 28.5.2015 .

Laboratory Use Only

Storage Instructions:

APTT may be falsely shortened if the venesection is traumatic.

APTT be falsely prolonged if the tube is 'underfilled' or the patient has a raised haemoglobin/haematocrit.