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Activated Partial Thromboplastin Time

APTT aPTT Partial Thromboplastin Time (PTT)
Sodium citrate (blue top) seconds

About this test

Evaluates the intrinsic coagulation pathway (FXII, FXI, FIX, FVIII) and common pathway. Extended in haemophilia A (FVIII) and B (FIX), lupus anticoagulant, and heparin therapy.

Reference Ranges

Sex Age Range Notes
All ≥ 18 yrs 23 – 35 Adult; lab-specific ratio APTT/control also reported

Clinical Interpretation

Low / Decreased
Short APTT — early DIC, acute thrombosis (activated state).
High / Increased
Prolonged APTT — haemophilia A (FVIII↓), haemophilia B (FIX↓), vWD (severe), lupus anticoagulant (paradoxically thrombotic), heparin therapy, DIC, factor XII deficiency (not associated with bleeding).

Related Tests

Fibrinogen
Specimen
Sodium citrate (blue top)
Reporting Unit
seconds
Category
🩹 Coagulation

⚠ Clinical Note
Reference ranges are indicative. Always interpret results in the context of the individual patient and local laboratory reference intervals, which may vary.