Coagulation
Activated partial thromboplastin timeaPTT
Intrinsic and common pathway; monitors UFH and screens for factor deficiencies.
Sample
Citrated plasma
Clinical reference range
25 to 35 s
Adult
Conv: 25–35 s
Biology
What it measures
Surface-activated cascade through factors XII → XI → IX → VIII → common pathway.
Clinical use
Why we order it
Heparin monitoring, hemophilia, lupus anticoagulant.
Differential
Causes of abnormal values
Causes of HIGH
- ↑UFH
- ↑Hemophilia A/B (factor VIII/IX)
- ↑vWD
- ↑Lupus anticoagulant
- ↑Liver disease (late)
Related