Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
This is the time it takes anticoagulated plasma to clot after being exposed to phospholipids, activators and calcium. It is used as part of the clotting screen and is sensitive to deficiencies in Factors XII, XI, IX, VII, X, V, II and Fibrinogen, in addition it may also detect deficiencies in the contact factors (High Molecular Weight Kininogen and Pre-Kallikrein). The test is also sensitive to Heparin (both Unfractionated and Low Molecular Weight) and the Lupus Anticoagulant. APTT can be increased by a number of the Direct Oral Anticoagulants which are being used more widely.
Specimen container paediatric:
Light blue – sodium citrate
Specimen container adult:
Light blue – sodium citrate
Minimum volume paediatric:
1.3mL
Minimum volume adult:
2.7mL
Special requirements:
Tube must be correctly filled to line, to ensure correct ratio of blood to anticoagulant, ensure adequate mixing.
Sample stability:
8 hrs
Transport requirements:
Samples should be transported to lab without delay
Availability:
All times, both sites
Freq analysis:
Continuous
Add on test:
[email protected] (external)
Quality assurance:
UK NEQAS Blood Coagulation
Reference ranges:
APTT 26 to 37 seconds.
Note: For Haemostatic tests, paediatric reference ranges may be different to adult ranges.
Factors affecting result:
Heparin will prolong the APTT
Other info:
As part of a coagulation screen.