What happens during an INR prothrombin time test?
The test can be done with a sample of blood from a vein or a fingertip.
If a blood sample is taken from a vein:
The healthcare professional takes a blood sample from a vein in an arm with a small needle. After inserting the needle, he draws some blood and places it in a test tube or vial. He may feel mild discomfort when the needle is inserted or removed, but the procedure usually takes less than five minutes.
If a blood sample is taken from a fingertip:
The fingertip test can be done at the doctor’s office or home. If you take warfarin, your doctor may recommend that you get tested regularly with a home INR prothrombin time test kit. During this test, you or your healthcare professional:
You will use a small needle to prick a fingertip Collect a drop of blood and place it on a test strip or other particular instrument You will place the instrument or test strip in a device that measures the results. Home devices are small and lightweight.
If you use a home test kit, you will need to discuss your results with your healthcare professional, who will tell you how to submit your results.
Is there anything I need to do to prepare for the test?
If you take warfarin, you may need to take your daily dose after the test. Your doctor or healthcare professional will tell you if you need to follow any other special instructions.
Is this test at risk?
The risks of a blood test are minimal. You may feel mild pain or bruise where the needle is inserted, but most symptoms clear up quickly.
What do the results mean?
If you were tested because you take warfarin, your results would likely be given as INR levels. INR levels are often used because they make it easy to compare results from different laboratories and testing methods. If you are not taking warfarin, your results may be given as INR levels or the number of seconds it takes your blood sample to clot (prothrombin time).
If you take warfarin:
If your INR levels are too low, it may mean that you are at risk for dangerous blood clots. If your INR levels are too high, it may mean that you are at risk for dangerous bleeding.
Your doctor will probably change your warfarin dose to reduce these risks.
If you are not taking warfarin and your INR or prothrombin time results are not typical, it may indicate that you have:
A bleeding disorder that makes your body unable to clot blood well and causes excessive bleeding A clotting problem that causes your body to clot excessively in arteries or veins Liver disease Vitamin K deficiency: Vitamin K plays a vital role in blood clotting
What is The prothrombin time (PT) ?
The prothrombin time (PT) test measures the time it takes for a clot to form in a blood sample. A clot is a thick mass of blood that the body produces to seal blood leaks through wounds, cuts, or scrapes to prevent excessive bleeding.
The ability of blood to clot requires the participation of platelets (also called “thrombocytes”) and proteins called “clotting factors.” Platelets are oval-shaped cells that are made in the bone marrow. Most clotting factors are made in the liver.
When a blood vessel is ruptured, platelets are the first to reach the area of injury to seal off the blood leak and temporarily stop or reduce bleeding. But for the clot to become firm, challenging, and stable, clotting factors must also play a role.
The clotting factors of the human body are listed using Roman numerals (from factor I to factor XII). These factors work together in a specialized sequence, almost as if they were the pieces of a puzzle. When the last part is put in place, the clot forms, but if a part is missing or a defective part, the clot will not be able to form.
The PT test is used to assess the activity of five different clotting factors (I, II, V, VII, and X). The clotting time is lengthened when any of these factors is not detected but in an insufficient quantity or is defective. When the blood clotting process takes an abnormally long time, this can be an indicator of:
an inherited deficiency in clotting factors (which occurs in bleeding disorders such as hemophilia and von Willebrand disease) liver disease (since most clotting factors ion are made in the liver) a deficiency in vitamin K (because vitamin K is an essential component of several clotting factors) treatment with warfarin, a blood-thinning medicine certain medical conditions where the body uses or destroys clotting factors too quickly
Why is it done
Doctors may order a PT test as part of the evaluation for a bleeding disorder. Symptoms of bleeding disorders include easy bruising, nosebleeds that are difficult to stop, excessive bleeding after dental procedures, gums that bleed easily, excessive bleeding during the menstrual period, presence of blood in the urine or inflammation and pain in the joints.
Even in the absence of symptoms, doctors often use this test to ensure that the blood’s ability to clot is expected before a patient undergoes surgery.
This test may also be ordered to monitor the blood clotting ability of patients with liver disease or vitamin K deficiencies.
The PT test is also helpful in monitoring treatment effects with a blood-thinning drug called “warfarin.” Anticoagulants are often prescribed to prevent blood clots in patients who have had myocardial infarctions (heart attacks) or strokes or have had artificial heart valves implanted. Since the dosage is critical – enough medication must be given to prevent dangerous clots from forming, but not enough to cause excessive bleeding – careful monitoring is required.
In many cases, the PT test is performed in conjunction with the partial thromboplastin time (PTT) test so that clinicians can have a comprehensive and comprehensive view of how the clotting factors are working.
To undergo this test, you do not need to do any preparation. If your child takes a daily dose of anticoagulant, ask the pediatrician if she should change the timing of taking this medicine before undergoing the test.
If your child wears a shirt or short-sleeved shirt on the day of the blood test, it will make things easier and faster for the technical staff who will perform the blood test.