Prothrombin Time (PT/INR) Test: Booking, Price, and Results
About Prothrombin Time (PT/INR) Test: Booking, Price, and Results
| Field | Value |
|---|---|
| Also Known As | PT/INR test, Protime INR, Pro Time, INR test, Prothrombin Time/International Normalised Ratio, Coagulation test |
| Sample Type | Venous blood (collected in a citrate tube) |
| Fasting Required | Generally not required; if on warfarin, give your sample before your daily dose. |
| Report Time | 1 to 2 working days |
| Recommended For | All adults, males and females of any age |
| Price | Starting at ₹3,700 |
What Is a Prothrombin Time (PT/INR) Test?
The PT/INR test measures how quickly your blood forms a clot. It evaluates the clotting proteins in your blood and is often prescribed for people who bleed easily, those with liver disease, or patients taking blood-thinning medicines such as warfarin. The test is also called the Protime INR, Pro Time, or simply the INR test. A small sample of venous blood is drawn from your arm and sent to the laboratory for analysis.
What Does a Prothrombin Time (PT/INR) Test Measure?
The coagulation test looks at two related values and the clotting pathways that produce them. Here is what each component tells your doctor:
| Component | What It Measures |
|---|---|
| Prothrombin Time (PT) | The number of seconds a blood sample takes to form a clot |
| International Normalised Ratio (INR) | A standardised ratio that adjusts for differences between lab methods, making results comparable across laboratories |
| Extrinsic and Common Clotting Pathways | Activity of clotting factors II, V, VII, and X, plus fibrinogen (a protein that helps form clots) |
Why is a Prothrombin Time (PT/INR) Test Done?
A doctor may order this PT/INR test for several reasons, from investigating unusual bleeding to tracking long-term anticoagulant treatment.
Common Symptoms That May Require This Test
The following symptoms are among the most common reasons a doctor requests this test:
- Easy bruising without an obvious cause
- Frequent or unusually heavy nosebleeds
- Bleeding gums
- Prolonged bleeding from minor cuts
- Have liver problems
- Have unusually heavy menstrual bleeds
Conditions This Test Can Help Detect
This coagulation test can help identify a range of conditions affecting how blood clots. These include:
- Bleeding disorders where the body cannot clot blood properly
- Liver disease (the liver produces most clotting factors)
- Vitamin K deficiency
- Disseminated intravascular coagulation (DIC), a condition where abnormal clotting uses up clotting factors rapidly
- Deficiencies or antibodies affecting fibrinogen or clotting factors II, V, VII, or X
- Haemophilia (an inherited bleeding disorder)
- Clotting disorders, in which blood forms too many clots in the arteries or veins
Prothrombin Time (PT/INR) Test for Chronic Disease Monitoring
Patients taking warfarin (a blood-thinning medicine) need regular INR test monitoring to ensure their dose keeps the blood in a safe therapeutic range. When treatment begins, the INR is checked daily until a stable level is reached, then two to three times a week for one to two weeks. Once results remain consistent, testing can be reduced to every four to eight weeks.
How to Prepare and What to Expect
No major preparation is needed for a PT/INR test, but a few simple steps will help ensure your sample is reliable.
Do You Need to Fast?
Fasting is generally not required before this test. If you take warfarin, always have your blood drawn before taking your daily dose on the day of the test.
Practical Tips Before Your Test
Keep the following in mind before you attend your appointment:
- Tell your doctor about all prescription and non-prescription medicines you take, including aspirin, heparin, antihistamines, and vitamin C supplements.
- Mention any herbal remedies, Ayurvedic formulations, or traditional medicines.
- If you are on warfarin, do not take your daily dose until after your blood sample is collected.
- Drink enough water; good hydration makes veins easier to locate.
- Wear a short-sleeved or loose-sleeved top for easy access to your arm.
Step-by-Step Procedure
- A trained phlebotomist (blood collection specialist) will clean a small area on your arm with an antiseptic wipe.
- A fine needle is inserted into a vein, and a small amount of blood is drawn into a citrate tube.
- The needle is removed, and gentle pressure is applied to stop any minor bleeding.
- In the laboratory, a substance called thromboplastin is added to the sample to activate the clotting process.
- A specialist or an automated device records exactly how long the sample takes to clot.
- The sealed sample is processed, and your result is prepared, usually within the same day or within one to two working days.
Factors That Can Affect Accuracy
Several factors can influence your PT/INR test result. These include:
- High haematocrit levels (proportion of red blood cells) above 55%, which can artificially prolong the PT
- Heparin or lupus anticoagulants in the blood, which may alter clotting readings
- Underfilled sample tubes, haemolysis (rupture of red blood cells), or clotted specimens
- Sudden changes in vitamin K intake from the diet
- Alcohol consumption or changes in other medications
Understanding Your Prothrombin Time (PT/INR) Test Results
Your doctor will review your PT/INR test results alongside your medical history and any medicines you take. The table below lists generally accepted reference ranges.
| Parameter | Normal Range |
|---|---|
| Prothrombin Time (PT) | 11 to 13.5 seconds |
| INR (not on anticoagulants) | 1.1 or lower |
| INR (on warfarin, standard intensity) | 2.0 to 3.0 |
| INR (on warfarin, high intensity) | 2.5 to 3.5 |
These ranges are general guidelines. Your doctor will interpret your results based on your age, health history, and other factors. Always consult a qualified healthcare professional for personalised medical advice.
Results During Special Conditions
Certain health states can influence how results should be read:
- In liver disease, a high PT or INR reflects reduced production of clotting factors. However, the overall balance of clotting can be complex, and some patients may still face an increased risk of blood clots despite elevated values.
- Vitamin K deficiency caused by malnutrition, prolonged antibiotic use, or fat malabsorption can raise PT and INR values, even without a primary clotting disorder.
- During pregnancy, PT may be slightly shorter (by about 1 to 2 seconds) because the body naturally increases its tendency to clot.
- Newborns normally show a prolonged PT of 12 to 21 seconds, which returns to the adult range within 7 to 10 days after birth.
How to Maintain Healthy Levels
These general wellness habits can support healthy clotting function:
- Keep your vitamin K intake consistent. If you are on warfarin, avoid sudden large increases or decreases in green leafy vegetables such as spinach and kale.
- Limit alcohol, as it can interfere with clotting factor production and affect how warfarin works in the body.
- Share a full list of your medicines, supplements, and herbal remedies with your doctor at every appointment, as many substances interact with clotting pathways.
Lupin Diagnostics Prothrombin Time (PT/INR) Test Price and Home Collection
The PT/INR test is available at Lupin Diagnostics across India, with prices starting at ₹3,700, and home sample collection is available in most cities.
| City | Approximate Price (₹) |
|---|---|
| Guwahati | ₹3,700 |
| Mumbai | ₹3,700 |
| Bangalore | ₹3,700 |
| Chennai | ₹3,700 |
| Kolkata | ₹3,700 |
| Hyderabad | ₹3,700 |
| Pune | ₹3,700 |
| Bhopal | ₹3,700 |
Prices are indicative and may vary by location. Please confirm the current price at the time of booking.
How to Book
- Select the test on the Lupin Diagnostics website.
- Choose your city and preferred time slot.
- Opt for home sample collection by a certified phlebotomist, or visit your nearest Lupin Diagnostics centre.
- Receive your report via email or WhatsApp within the stipulated turnaround time.
Home Collection
Lupin Diagnostics offers home sample collection for the PT/INR test across multiple cities in India. All samples are processed in NABL-accredited laboratories by qualified technologists. Your digital report is delivered directly to your email or WhatsApp, so there is no need to collect a physical copy.
Frequently Asked Questions
PT is expressed in seconds and shows how long blood takes to clot. The INR is calculated from the PT result using a formula that accounts for differences in testing methods across laboratories. This makes the INR test a more reliable way to compare results from different labs or across time.
Warfarin thins the blood to prevent harmful clots, but the dose must be carefully controlled. A PT/INR test tells the doctor whether the dose is too low (raising the risk of clots) or too high (raising the risk of bleeding), so adjustments can be made to keep values within the target therapeutic range.
When you first start warfarin, testing is needed daily until your INR is stable. Frequency is then reduced to two to three times a week, then weekly, and eventually every four to eight weeks once your levels remain consistent. Your doctor will set the schedule based on how stable your results are.
Fasting is generally not required before a coagulation test like this one. Some labs may suggest overnight fasting of 8 to 12 hours as a precaution. If you take warfarin, it is important to have your blood drawn before taking your morning dose.
A high INR means blood is clotting more slowly than normal. Common causes include an excessive dose of anticoagulant medication, interactions with other medications such as aspirin or certain antibiotics, liver disease, and bleeding disorders that reduce clotting factor production.
Yes. The liver produces most of the proteins needed for clotting. When the liver is damaged or not working well, it makes fewer clotting factors, which prolongs the PT and raises the INR. A persistently high INR in the context of liver disease can indicate significant liver damage.
This is a routine blood draw with minimal risk. You may feel brief discomfort or notice slight bruising at the needle site, but this usually resolves quickly. People with known bleeding disorders may experience slightly longer bleeding at the puncture site, which the phlebotomist will manage with applied pressure.
Prothrombin Time (PT/INR) Test: Booking, Price, and Results
