Lab test · Hematology
Prothrombin Time with INR (PT/INR)
Clotting time, blood thinner check
- Blood sample
- No fasting
- Report within 24 hours
- Home collection
What this test is for
Clotting time, blood thinner check
The prothrombin time (PT) measures how long it takes your blood to clot. The INR (international normalised ratio) is a standard way of reporting the PT so that results from different laboratories can be compared. The test checks clotting factors made by the liver, several of which need vitamin K. Doctors use it to monitor warfarin, to check clotting before surgery and to help assess liver function.
Why a doctor may order it
- To check that warfarin is thinning the blood by the amount your doctor intends
- To look for a cause of unexplained bleeding or bruising
- Before an operation or a procedure such as a biopsy
- To help assess how well the liver is working in liver disease
- When a shortage of vitamin K is suspected
How to prepare
Fasting: Not needed.
You can eat and drink as normal. If you take warfarin, keep taking it exactly as prescribed and tell the collector when you took your last tablet. Sudden changes in diet, especially green leafy vegetables, and some antibiotics or herbal remedies can change the INR, so mention any recent changes. Do not stop or change a medicine without talking to your doctor.
At home
- Sample
- Blood sample
- How it works
- The collector takes a small blood sample from a vein in your arm into a special clotting tube that has to be filled to the right mark. If you take a blood thinner, you may need to press on the spot a little longer afterwards. The visit takes only a few minutes.
- Report
- Within 24 hours of collection.
What the results can mean
Your report shows the PT in seconds and the INR next to the laboratory's reference range. A higher INR means your blood takes longer to clot; this is expected on warfarin but can also be caused by liver disease or a lack of vitamin K. If you take warfarin, your doctor sets a target range for you, and a result above it raises the risk of bleeding while a result below it may mean less protection from clots. Your doctor will interpret the result and decide on any change.
What's included
This test reports 2 measurements:
- Prothrombin time
- INR
Related tests
- Activated Partial Thromboplastin Time (APTT)Blood clotting time৳450
- Liver Function Test (LFT)A liver function test is a group of blood tests that show how well your liver is working and whether it is inflamed or damaged.
- Platelet CountPlatelets are tiny cell fragments in the blood that help it clot and stop bleeding.
- Complete Blood Count (CBC)A complete blood count looks at the three main types of cells in your blood: red blood cells, which carry oxygen; white blood cells, which fight infection; and platelets, which help blood to clot.
- D-dimer TestD-dimer is a small protein fragment released into the blood when a blood clot breaks down.
- Blood Grouping and Rh TypingBlood group & Rh type৳110
Questions people ask
What is INR and why is it used?
INR stands for international normalised ratio. It adjusts the PT result so that it means the same thing in any laboratory, which is important for people on warfarin whose results are compared over time.
Do newer blood thinners need INR checks?
Newer blood thinners such as apixaban, rivaroxaban and dabigatran do not usually need regular INR monitoring. PT/INR is mainly used for people taking warfarin.
How often should INR be checked on warfarin?
Your doctor decides this. Checks are usually more frequent when warfarin is first started or after a change, and less frequent once your INR is stable.
What does a high INR mean?
It means your blood is taking longer than usual to clot. On warfarin this raises the chance of bleeding, so contact your doctor promptly, and get urgent help if you notice heavy bleeding, black stools or blood in your urine.
How much does a PT/INR test cost in Dhaka?
With Mukti Health the price is ৳350, and the sample is collected at your home in Dhaka. You see the price again before you confirm the booking in the Mukti Health app.
Can I do the PT/INR test at home in Dhaka?
Yes. Book it in the Mukti Health app and a trained sample collector comes to your home in Dhaka to take the blood sample. You do not need to go to a laboratory.
How long does the PT/INR report take?
The report is usually ready within 24 hours of the sample being collected.