Doctor's Assessment Included
Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
aPTT
aPTT provides essential coagulation screening. As part of a preventive health panel, it helps identify clotting abnormalities before they become clinically significant.
What It Measures
This test measures the time in seconds for plasma to clot after activation of the intrinsic pathway. A prolonged aPTT may indicate clotting factor deficiencies, the presence of inhibitors such as lupus anticoagulant, or heparin effect.
Why It Matters
aPTT helps identify bleeding disorders, monitor anticoagulant therapy, and detect clotting inhibitors. It evaluates factors XII, XI, IX, VIII, X, V, II (prothrombin), and fibrinogen.
When to Test
aPTT is commonly ordered before surgery, when a bleeding disorder is suspected, to monitor heparin therapy, or as part of a coagulation assessment. It is frequently ordered alongside PT/INR.
Symptoms
Low Levels
A shortened aPTT may suggest a hypercoagulable state and could be associated with increased thrombosis risk. However, a short aPTT alone is rarely clinically actionable.
High Levels
A prolonged aPTT may indicate clotting factor deficiency, vitamin K deficiency, liver disease, lupus anticoagulant, or anticoagulant medication effect. Symptoms of underlying conditions may include easy bruising, prolonged bleeding, or nosebleeds.
Lifestyle Tips
If aPTT abnormalities are detected, your healthcare provider will investigate the cause. Ensure adequate vitamin K intake through leafy green vegetables. Report any unusual bleeding or bruising to your healthcare provider promptly.
Frequently Asked Questions
What is the difference between aPTT and PT?
aPTT evaluates the intrinsic pathway, while PT evaluates the extrinsic pathway. Together they provide a comprehensive view of the coagulation system.
Why might aPTT be prolonged in someone without bleeding?
Lupus anticoagulant can prolong aPTT but paradoxically increases thrombosis risk rather than bleeding risk. This is an important diagnostic distinction.
Does diet affect aPTT?
Diet alone rarely affects aPTT significantly. However, severe vitamin K deficiency or malnutrition can prolong clotting times.