Clotting Time (C T)
- Clotting Time is done on a fresh sample of blood and the patient needed to be in the lab.
- Clotting Time is advised to find bleeding disorder, most likely due to clotting factors deficiency.
- To Diagnose hemophilia.
- It does not diagnose mild coagulation disorders.
- For the clot formation prothrombin is converted into thrombin.
- Thrombin converts soluble fibrinogen into insoluble fibrin.
- For this process clotting factors are needed along with calcium.
- Also assisted by the factors produced by platelets and damaged tissue.
- So clotting time is the time needed for the generation of thrombin from the complex system of clotting.
- When there is any deficiency in these factors, it will lead to prolonged clotting time.
- Now, it is rarely used because of the variation, instead, the clotting factors are more accurate.
- Clotting time can be estimated by two methods:
- Capillary method.
- Test tube method.
- Perform this test at 37 ° C.
- For the tube, the method takes 4 ml of blood and start the time.
- Note the time when there is the first appearance of the clot formation.
- This test can be done in multiple tubes to be more accurate.
- The expected range is 4 to 10 minutes.
- The glass tube method clotting time is 5 to 15 minutes.
- Siliconized tubes clotting time is 19 to 60 minutes.
Causes of prolonged clotting time are:
- Coagulation factors deficiencies which may be:
- Drugs like heparin and thrombin inhibitor.