Prothrombin Time TestAbhishtita MudunuriLast Updated on 19th January 2022
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What is the PT INR test used for?
The PT test or prothrombin time test is used as a starting point for evaluating bleeding or clotting problems. A doctor can acquire insight into what bleeding or clotting issue may be present by combining the findings of the PT INR test.
The PT tests are often performed selectively as pre-surgical or before other invasive procedures to screen for possible bleeding tendencies based on carefully acquired patient histories. It is mainly used to monitor patients receiving anticoagulation medicines like warfarin. PT is also used to determine whether blood clot prevention medication is effective or not.
Procedure for PT INR test
A blood sample drawn from your fingertip is used for this test. A fingertip test can be done at the doctor’s office or at home. If you are on warfarin, your doctor may suggest you regularly test your blood with an at-home PT INR test kit or get it tested at a reliable lab .
During this test, the lab technician will do the following:
- Puncture your fingertip with a tiny needle.
- Take a drop of blood and place it on a test strip.
- Insert the test strip into a device that can calculate the results.
- Devices for use at home are tiny and light.
When the needle is inserted and removed, you may feel a slight sting. The whole process normally takes less than five minutes.
How to prepare for the PT INR test?
You usually don’t need to do anything special before the test. However, many medications, foods, and illnesses might impact this test finding. Inform your doctor about any medications and supplements you are taking, as well as any dietary changes.
A PT test is an entirely risk-free procedure. However, there is little risk of infection, hematoma, or fainting after any blood draw.
Things to consider after the PT INR test is complete
The test will tell you how long it took your blood to clot. What is normal varies depending on the lab, so see your doctor to help you understand what your numbers mean.
You may receive the results within a few hours. However, some labs may take few days. If your doctor uses a finger stick test, you can obtain results in a matter of minutes.
Liver function test , clotting time, bleeding time and other tests may also be ordered by your healthcare physician.
What types of conditions can the PT INR test detect?
Certain medications, such as warfarin (Coumadin, Jantoven), tend to thin the blood. The PT INR test assists doctors in understanding the dosage to be prescribed.
In addition, if the individual has one of the following conditions, the doctor may request a PT INR test.
- Normal blood clotting before surgery
- Liver Disorders
- Vitamin K deficiency
- Immune system issues
- Certain cancers, such as leukaemia
- Bone marrow issues
- Bleeding disorders.
How much does the PT INR test cost?
PT INR test cost ranges from Rs 200 to Rs 500. The price of the test varies from lab to lab and is different in different cities. Generally, it starts from Rs 200. If your test result is abnormal, the cost starts adding up with all the other tests the doctor asks to do.
*Disclaimer: The value varies based on location, time, and your preferred lab partner.
How long does it take to get the results for the PT INR test?
You can expect to get the results for the PT INR test within 24 to 48 hours after the sample is collected. However, in some instances, depending on the location, medical advice, and preferred lab partner, it may take longer.
What do abnormal PT INR test results indicate?
The laboratory values of a PT and INR are used to evaluate a level of anticoagulation when you’re on a medication called Coumadin or warfarin. That medication is often used to help thin out the blood in the cases of blood clotting issues.
When the values are too high, it generally means that your blood has become too thin, and it predisposes you or makes you more likely to have bleeding when you shouldn’t.
If your value is too low, it means that your blood is more likely to form a clot, which is what we’re trying to prevent.
A prolonged PT indicates that the blood is taking an exceptionally long time to clot. This might be caused by liver disease, a lack of vitamin K, or a lack of coagulation factor (e.g., factor VII deficiency). The PT result is frequently analysed in combination with the PTT test to determine what condition may be present.
Disclaimer: Please consult with your doctor to interpret the test reports.
PT INR is not a diagnostic test by itself, as it simply indicates a problem with the bleeding or clotting time. It suggests that more testing may be necessary to determine the definitive cause and diagnosis of the problem. As a result, in addition to the PT INR test, or along with this test, other tests that may be requested. If your doctor suspects you have a bleeding issue, you may be subjected to tests to determine this, that includes:
- PTT test
- Fibrinogen testing
- Platelet count
- Coagulation factors tests (searches for a genetic disorder causing nosebleeds and other bleeding issues)
- Liver Function test
- Bleeding and Clotting time test
How to read the PT INR test report?
If you were tested because you are on warfarin, the results would most likely be in the form of INR levels (International Normalised Ratio). INR levels are often used to compare results from different laboratories and make test procedures simpler.
For healthy individuals, Normal INR: 0.9 – 1.3
Normal INR values in people taking anticoagulant medicine: 2.0 – 3.0
High risk of bleeding: >5.5
If INR values are less than 0.5, the person has a high risk of blood clotting.
INR values are useful to adjust the dosage of anticoagulants and how well these medicines are working to prevent blood clots. By determining the INR values, the doctor will determine how these medicines are working and how this is effective in preventing a blood clot.
For patients on anticoagulant medicine, the dosage is reduced if the INR value is 4, which is more than normal.
If INR value is less than normal, then the dosage of medicine is increased.
If you do not take warfarin, your results may be in the form of INR levels or the time it takes for your blood sample to clot (prothrombin time).
In normal people, prothrombin time: 10-15 seconds. Whereas, prothrombin time for people taking anticoagulant medicine: 22-35 seconds
Critical value: >65 seconds. These people should consult a doctor.
Why book the PT INR test?
When a person takes the anticoagulant medicine warfarin, a PT and INR are ordered regularly to ensure that the drug has the intended effect. Also, a test can be ordered when a person is not taking anticoagulants but exhibits signs or symptoms of excessive bleeding or clotting, such as:
- Unexpected bleeding or easy bruising
- Gums that bleed
- A blood clot that has formed in a vein or artery.
- An acute illness, such as disseminated intravascular coagulation (DIC), can induce both bleeding and clotting due to the fast depletion of coagulation factors.
- A chronic condition such as severe liver disease that can impair hemostasis.
Symptoms of a clotting disorder include:
- Tenderness or discomfort in the legs
- Leg swelling
- Redness or red streaks on legs
- Breathing problems
- Chest ache
- Rapid pulse rate
Before surgery, a PT INR may be requested if there is a high risk of blood loss and/or if the person has a clinical history of bleeding, such as frequent or severe nosebleeds and easy bruising, which may suggest the presence of any bleeding condition.
PT INR test at home—how does it work?
The PT INR test is just like any other blood test. A lab technician visits your home when you book your tests through the MFine app. The lab technician first punctures your fingertip with a tiny needle, takes a drop of blood and places it on a test strip and then inserts the test strip into a device that can calculate the results. Or a blood sample is collected from one of your veins in the arm by piercing the needle.
Are there any risks involved with the PT INR test?
Blood tests are low-risk procedures. While problems from routine blood tests are uncommon, they are possible.
- Pain at the location of needle insertion
- Feeling weak or lightheadedness
- Anxiety over needles
- Excessive bleeding, mainly if you use blood thinners
If you feel dizzy during or after a blood draw, or if the site continues to bleed, inform your doctor. Cover and clean your puncture site, and keep an eye out for signs of infection (pain, redness, heat, swelling, fever, chills) during the following few days. If symptoms of infection appear, get immediate medical help
What can affect the results for the PT INR test?
Some antibiotics might cause an increase in PT and INR. Also, some foods, such as liver, broccoli, chickpeas, green tea, kale, turnip greens, and soy products, might have an impact on your test results. Your doctor will advise you whether you need to regulate specific foods or drinks or altogether avoid them.
Make sure your doctor is aware of any medications, vitamins, herbs, or supplements you are taking. This covers OTC, prescription, and illicit medications. Many drugs, ranging from aspirin to steroids, might have an impact on your results.
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Frequently asked questions | FAQs
Is the lab technician coming for PT INR test sample collection vaccinated?
Yes. Our lab technicians are fully vaccinated. Further, they also ensure safety by wearing masks and gloves and frequently sanitising themselves during sample collection.
Does MFine provide the interpretation for the results along with the reports?
Yes, MFine provides the interpretation for the result and the reports. You can also avail a free medical consultation with a doctor to understand your reports accurately. The doctor will also advise and prescribe medicines, if required, based on the results.
How can I download my PT INR test report?
- Login to MFine
- Go to your profile
- Click on Attachment and Reports
- Click on Lab Report
- Download the report
Are there any discount offers running on the PT INR test?
Usually, you can avail of up to a 50% discount on PT INR test through MFine. However, the discount and test price may vary based on lab partner and location.
Can your diet impact INR levels?
Yes, if you are on anticoagulant medicine like warfarin, certain foods containing vitamin K, such as dark leafy greens or green tea, may reduce its effectiveness. While using warfarin, having alcohol, cranberry, and grapefruit products might increase the risk of bleeding that impacts INR levels.
What if my PT test shows an abnormal level?
After an abnormal PT test result, your medical doctor may wish to do further testing. If you are not already taking any medicine that affects blood clotting factors, you may need to start taking one to normalise your levels. If you take a drug that affects coagulation, your dosage may need to be adjusted if your PT is not within the normal range.
For what conditions a prothrombin time test is prescribed?
Platelet count, fibrinogen testing, coagulation factor tests, von Willebrand factor, and lupus anticoagulant testing are some of the conditions for which the Prothrombin Time is prescribed along with the Partial thromboplastin test (PTT).
What are the Clotting factor deficiency tests I should be aware of ?
Platelet count, fibrinogen testing, coagulation factor tests, von Willebrand factor, and lupus anticoagulant testing are some of the clotting factors tested during bleeding disorders.
Is fasting required for a prothrombin time test?
There is no need to fast before a PT test. A PT test will require a blood sample. This is an outpatient procedure usually performed at a diagnostic lab. It takes only a few minutes and causes little to no pain.
What is the normal clotting time?
A person’s natural clotting time ranges between 8 and 15 minutes. It is possible to detect whether a person has hemophilia or von willibrand’s disease by analysing the time it takes for blood to clot. Bleeding time can still be deemed normal if it is between one to eight minutes.
What foods should you avoid while on blood thinners?
Patients on Coumadin or Warfarin should avoid vitamin K-rich meals and supplements. Blood thinners prevent blood clots. However, Vitamin K can thicken your blood. If a patient consumes vitamin K-rich foods regularly, the vitamin K will react with the medicine, making it more difficult to regulate the patient’s blood consistency.
Disclaimer: The content is uniquely informative and is meant for educational use. Kindly use the content only in consultation with an appropriate certified or registered healthcare provider.