What is a blood test?
A blood test is when a sample of blood is drawn for analysis in a laboratory. Doctors order blood tests to check things like glucose, hemoglobin, or white blood cells in the blood. This can help detect problems, such as an illness or medical condition. Sometimes blood tests can help them see how well an organ (such as the liver or kidneys) works.
What is prothrombin time?
The prothrombin time (PT) test measures the time it takes for a clot to form in a blood sample. Clotting ability is essential to prevent excessive bleeding. There are some proteins (called clotting factors) that are essential for the blood to clot well. If there is not enough clotting factor, or if one of them is not working the way it should, it may take longer than usual for the clot to form.
Why is this test done?
PT is done to evaluate bleeding problems. Your child may have this test if he has had a lot of bruising or bleeding if he has a medical condition that can cause clotting problems, if he is going to be operated on, or if he is going to have a procedure that may cause bleeding. . The PT test is also done to determine the level of clotting in children who are taking blood-thinning medications.
How should we prepare for the test?
Your child can eat and normally drink unless another test is also required at the same time that he requires prior fasting. Tell your child’s doctor about any medications because some medications can influence the test results.
Wearing a short-sleeved shirt on the day of the test can make things easier for your child; They can also carry a toy or book to distract them.
How is the test done?
In most blood tests, a sample of blood is drawn from a vein. For this purpose, a health professional:
Clean the skin places a rubber band (tourniquet) around the area to make the veins swell with blood.
inserts a needle into a vein (usually in the arm, either on the inside of the elbow or on the back of the hand)
Insert the blood sample into a vial or syringe.
remove the gum and remove the needle from the veinWhy is it done
In most cases, the prothrombin time is controlled if you are taking warfarin, an anticoagulant medication. In this situation, the prothrombin time is expressed as an international normalized ratio (INR).
Your doctor may recommend a prothrombin time test before surgery if there are any concerns about your blood’s ability to clot.
The prothrombin time test can also be done to assess your liver disease. It is one of many tests used to screen people awaiting liver transplants. This screening test (known as the model for end-stage liver disease) is a scoring system for evaluating the severity of the chronic liver disease.
If your doctor suspects you have other health problems, such as liver problems or a bleeding disorder, you may need other tests to confirm your condition.
Request a Consultation at Mayo Clinic
Risks
A prothrombin time test is similar to any other blood test. You may experience minor pain or bruising where the blood is drawn on your arm.
What you can expect
During the test
Obtaining the blood sample for the prothrombin time test usually takes a few minutes, like any other blood test.
After the test
The blood may be sent to a laboratory for testing. If the lab test is done on-site, the results could be ready in a few hours. If the doctor sends the blood to an outside laboratory, it could take several days to receive the results.
At some anticoagulation clinics, the nursing staff takes a finger stick blood sample from you and gives you test results in minutes while you’re still in the exam room.
Home analysis
Home use test kits are available for people who take blood thinners for long periods and are trained to take and analyze blood samples.
Results
The results of the prothrombin time test can be presented in two ways.
What is a prothrombin time test with INR (PT / INR)?
The prothrombin time (PT) test measures the time it takes for a clot to form in a blood sample. The international index Normalized (INR) is a type of calculation based on the results of prothrombin time tests.
Prothrombin is a protein produced by the liver. It is one of several substances known as clotting factors. When a person is cut or injury that causes bleeding, clotting factors work in concert to form a blood clot. When the levels of clotting factors are too low, you can bleed too much after an injury. If these levels are too high, dangerous clots can form in the arteries or veins.
The prothrombin time test with INR helps determine if your blood is clotting normally. It also checks to see if clot-prevention medications (anticoagulants) are working well.
Alternative names: prothrombin time / international normalized index; clotting time: prothrombin time
For what do you use it?
The prothrombin time test with INR is often used to:
See if warfarin has the desired effect. Warfarin is a blood-thinning medicine used to treat and prevent dangerous blood clots (Coumadin is a common brand name of warfarin)
Finding out the cause of abnormal blood clots
Find out the cause of unusual bleeding
Check the coagulation function before an operation
Detect liver problemsThe prothrombin time test with INR is usually done with the partial thromboplastin time (PTT) test. The TPT test also detects clotting problems.
Why do I need a prothrombin time test with INR?
You may need this test if you take warfarin regularly. The test checks if you are taking the correct dose.
If you are not taking warfarin, you may need this test if you have bleeding disorder (clotting problem) symptoms.
Some of the symptoms of a bleeding disorder are:
Heavy bleeding for no apparent reason
Easy bruising
Unusually heavy nosebleeds
Weighty menstrual periods in womenSome of the symptoms of a clotting problem are:
Pain or tenderness in the legs
Swelling in the legs
Redness or red streaks on the legs
Difficulty breathing
Cough
Chest pain
Fast heartbeatYou may also need a prothrombin time INR test if you have an operation scheduled. The test confirms if your blood is clotting generally, so you don’t lose too much blood during the procedure.
