Plasma that is deficient in any of the factors in the intrinsic pathway will demonstrate a prolonged activated partial thromboplastin time (APTT). This assay is used to identify and monitor the treatment of patients with specific intrinsic factor deficiencies.
The 9:1 blood/citrate ratio must be kept constant. Adjustments for the amount of anticoagulant should be made when the hematocrit is abnormal (above 55%). Mix immediately to prevent clotting.
Collection Instructions
Send whole blood sample(s) at room temperature as soon as possible.
If specimens cannot be shipped immediately, centrifuge and separate plasma within 1 hour of collection, send frozen plasma on dry ice
STAT: 24 hours, 7 days/week.
Routine: Samples are aliquotted and frozen. The assay is run in batches.
4 hours
1-2 weeks
Adult: 0.58 - 1.90 U/mL
Full-term Infant at Birth: 0.50 – 1.78 U/mL
Premature Infant of 30 to 36 Weeks gestational age: 0.50 – 2.13 U/mL
In case of discrepancies, always interpret results using reference ranges as stated on laboratory reports and/or electronic patient chart.