Investigation Name:Prothrombin Time (PT)/INR

Alias or Abbreviation:PT/INR

Pathology Laboratory:Haematology Ext 88245

Requestable Seperately?No

Part of Profile:CS

Tests in Profile:PT, APTT, FIB

E-Requesting Tab:BASIC-Blds

Lower Reference Range Limit:9.5

Upper Reference Range Limit:12.5

Units:seconds

Minimum Sample Volume:FILL TO LEVEL

Expected Turnaround Time:<4 hours

Test Code:PTI

Sample Type:

Maximum Add on Time:24 hours

Complex Reference Range:If patient is on warfarin the INR should be used for monitoring. The INR range varies depending on the reason for the anticoagulation. Age specific paediatric/neonatal reference range :- Premature (24-29 weeks - Day 1) PT 11.7 - 21.6 seconds Premature (30-36 weeks - Day 1) PT 10.6 - 16.2 seconds Premature (30-36 weeks - Day 30) PT 10.0 - 13.6 seconds Full term (37-40 weeks - Day 1) PT 10.1 - 15.9 seconds Full term (37-40 weeks - Day 5) PT 10.0 - 15.3 seconds

Collection Conditions / Other Information:Full sample should be tested ASAP however the INR is stable for 24 hours. Paediatric sample tubes are available from the laboratory for children and difficult to bleed patients. These tubes require 1ml of blood to be taken. Underfilled or overfilled samples will not be processed as the ratio of anticoagulant to blood in the tube will be incorrect. Clotted and grossly haemolysed samples cannot be processed. Haemolysis, Icterus and lipaemia may interfere with testing and so manual methods may be required to gain results.

Referred to Another Laboratory?No