Clotting Time


It is the time required for blood to coagulate in vitro under standard conditions.


  1. Capillary Tube Method (Normal Range  – 8 to 15 minutes)
  2. Test Tube Method
  3. Others : aPTT, Prothrombin time, INR

Prothrombin Time

Normal Range – 25 to 30 seconds

Abnormal Prothrombin Time is seen in :

  1. Haemophilia
  2. Liver Pathology
  3. Malabsorption
  4. Warfarin overdose


International Normalized Ratio

When INR is too high (>4.5) there is increased risk of major haemorrhage as the blood is too thin.

When it is too low (<2.0) there is increased risk of thromboembolism as the blood is very viscous.

– Jainam Shah

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