What is Clotting Time?
A clotting time test is conducted to measure the time taken by the blood to form a clot. This clotting mechanism is essential to stop the bleeding after an injury. Coagulation is another term for blood clotting, and it is a series of complex interactions between the platelets, proteins, and the clotting factors.
The clotting time test is vital in the detection of the underlying disorders if any such as hemophilia, deep vein thrombosis, thrombocytopenia, and others. Patients who are undergoing surgery, those with a family history of disorders associated with coagulation abnormalities, and individuals experiencing easy bruising or bleeding without any known reason are advised to get this test done.
How is the Test Performed?
A trained technician draws blood using a needle. The sample is then exposed to conditions similar to that of the body to measure the clotting time.
Preparation
- Avoid taking aspirin and anticoagulants before the test.
- Keep your doctor informed about the medications you are taking.
Laboratory Analysis
- The sample is analyzed in the laboratory for the clotting time using a manual method for instance the capillary tube method although less common today or an automated coagulation analyzer that uses the light scattering or mechanical clot detection method.
What are the symptoms that prompt this test?
The healthcare provider orders this test when an individual is exhibiting symptoms indicative of a clotting disorder. The symptoms vary according to the severity, abnormal clot formation, or excessive bleeding. The general symptoms observed in different age groups are mentioned below;
Neonates
- Unusual bruising
- Bleeding from umbilical cord stump without a known reason
- Circumcision sites and heel pricks bleeding for a prolonged time.
Children
- Recurrent nosebleeds that do not stop easily
- Bleeding for a long time after minor injuries or cuts
- Swelling of the joints due to internal bleeding
Adults
- Bruising easily due to low or no trauma or injury
- Bleeding heavily during menstruation often referred to as menorrhagia
- Brushing or flossing results in gum bleeding
- Bloody stool or urine
- Prolonged bleeding after teeth extraction and surgeries.
Symptoms Associated with Thrombosis
- Swelling
- Redness
- Pain
- Shortness of breath followed by chest pain
- Vision changes
- Neurological symptoms possibly caused by the blood clots in the brains
What are Normal Ranges for This Test?
The clotting time varies according to age for instance in newborns the clotting time is prolonged and underlying conditions. The generally accepted reference range for clotting time is mentioned below;
Manual Method- Capillary Tube Method – 2 to 8 minutes
Automated Coagulation Analyzer- Activated Partial Thromboplastin Time – 25 to 35 seconds
**The values above are for general guidelines only and may vary according to the laboratory’s reference ranges and methodology. **
What Happens if Test Results Show Abnormal Levels?
Abnormal levels of clotting time indicate an underlying condition. The possible conditions that are associated with prolonged or shortened clotting time are given;
Prolonged Clotting Time Indicate
- Hemophilia
- Liver disease as the liver is responsible for the production of clotting factors, disruption in its function can result in longer clotting time.
- Deficiency of Vitamin K
- Von Willebrand Disease is a bleeding disorder caused due to the von Willebrand factor’s deficiency or impairment. These factors aid
- platelets in adhering to the injury site.
- Certain medications particularly warfarin or heparin (blood thinners)
Shortened Clotting Time Indicate
- Genetic disorders such as Leiden mutation of factor V, or mutation of prothrombin gene collectively called thrombophilia
- Disseminated Intravascular Coagulation is a condition in which widespread blood clots are formed.
- Clotting disorders associated with pregnancy such as preeclampsia and antiphospholipid syndrome.
If abnormalities are detected further testing is required such as platelet count, fibrinogen level, genetic testing, and lifestyle modifications.
