Abnormality | Cause | |
Isolated prolongation of PT | 1. Vitamin K deficiency (HDN, malabsorbtion) | |
2. Liver failure | ||
3. (Warfarin) | ||
Isolated prolongation of APTT | 1. VWD | |
2. Coagulation factor deficiencies: | ||
• Factors VIII, IX and XI—clinically significant | ||
• Factor XII—not significant | ||
3. Lupus anticoagulant—DRVVT | ||
4. (Heparin) | ||
Combined abnormalities | 1. Liver failure | |
2. Vitamin K deficiency | ||
3. (DIC) | ||
4. Rare—afibrinogenaemia or dysfibrinogenaemia |
( ) Suspect in certain circumstances as described in text.