INR Blood Test London
INR Blood Test at 117a Harley Street, London, from £39.38, with results in 1 working day. An INR test measures how long blood takes to clot. It is commonly used to monitor warfarin and can also contribute to investigation of clotting or liver-related concerns. Laboratory testing starts from £39.38.
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An INR test measures how long blood takes to clot. It is commonly used to monitor warfarin and can also contribute to investigation of clotting or liver-related concerns.
Do not change your warfarin dose unless your anticoagulation clinician instructs you to. Medical Express Clinic supplies a laboratory INR result; it does not replace your anticoagulation service or guarantee same-day dose advice. Check that your dosing clinician will accept an external result and that a one-working-day turnaround fits your monitoring schedule.
Or call 0207 499 1991.
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What is an INR blood test?
The International Normalised Ratio (INR) standardises clotting time for monitoring anticoagulation, especially warfarin. Warfarin dosing is monitored using INR blood tests and the target varies by indication.
This booking provides the laboratory INR result. Dose changes remain the responsibility of the prescribing clinician.
INR (PTIM)
INR
PTIM · £39.38
Analytes: International Normalised Ratio (INR)
Turnaround: Usually 1 working day
- •INR measures clotting time relative to a standard reference, used to monitor warfarin and assess clotting in selected clinical situations.
- •INR is sometimes relevant when liver function affects clotting proteins; a liver function test can be booked separately for that question.
- •INR does not monitor direct oral anticoagulants, which use different laboratory tests.
Have a doctor review your INR result
The test gives your INR. Your target range depends on why warfarin was prescribed, and dose decisions stay with the clinician or anticoagulation service that manages your warfarin, so send them the result as soon as you have it.
If you are visiting London, are between services or want a doctor to go through the result with you, book a private GP consultation as well.
- •Book the INR test on its own if your anticoagulation service has asked for a result
- •The report is usually ready within 1 working day
- •Book a follow-up consultation to go through the result and agree the next step
GP Consultation
£150
Review your INR result, your warfarin record and any new medicines with a doctor.
Follow-Up Consultation
£100
For existing patients: go through your result with a doctor and agree the next step.
Only need the laboratory test? Our sister clinic lists the INR test at Blood London.
Warfarin monitoring and clinician-requested clotting checks
- •Warfarin monitoring
- •A clinician-requested clotting assessment
- •Review of an unexpected clotting result
Dose records and medicines
No fasting is required. Bring your current warfarin dose, anticoagulation record and medication list. Do not change medication unless instructed by your clinician.
Mention any missed doses, new medicines or recent illness before sampling. The report is usually ready within 1 working day and should go to the clinician who manages your anticoagulation, who can then advise on dosing.
What an INR result is for
- •The target INR range depends on why warfarin was prescribed.
- •Urgent bleeding, severe headache or significant injury requires urgent medical assessment rather than routine testing.
Usually 1 working day. Your laboratory report is supplied securely.
The blood-test price covers the laboratory report, not a consultation. A separate GP consultation is £150 if you want a doctor to interpret the result with your symptoms and history.
Uncontrolled bleeding, a significant head injury, a severe sudden headache, blood in urine or stool, or an injury that could hide internal bleeding needs urgent assessment, not a routine online booking.
Source: NHS warfarin monitoring.
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Sources & References
- Warfarin dosing is monitored using INR blood tests and the target varies by indication. - NHS warfarin monitoring[Link]
Dr Penny Sheehan
Health Screening, Paediatrics and Menopause • GMC 6056535
“Dr Sheehan works in women's health, menopause care and health screening. She has training and experience in weight management, including GLP-1 receptor agonist prescribing, and a special interest in paediatric assessment.”
Service information reviewed 26 August 2026.
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What our patients say
“Quick, painless draw and 4-hour results”
“Had an appointment at 1:30 PM but got there early and the staff were happy to draw my blood earlier since there was availability. Quick and painless process with a professional phlebotomist. The turnaround time stated on the website for the test was 4 hours, and sure enough, I received my results super easy with no issues. Would recommend this service.”
“Heard, understood and reassured”
“The clinic is warm and welcoming. In my experience, every time I was there, I found myself heard and understood. My health issues have been tackled in the best of ways. Miss Arjeta is absolutely a master of blood tests, you will not feel anything. Dr Bakhtiar is knowledgeable and calm, I always feel reassured after speaking to him. I genuinely recommend this clinic.”
“Results faster than expected at a walk-in clinic”
“I recently had a blood test for rabbit allergies at Medical Express Clinic, and I'm extremely pleased with the service. Not only did I receive my results faster than expected, but the receptionist was fabulous, she answered all my questions and accommodated all my requests. It's the only walk-in clinic I found in central London with reasonable prices. Highly recommend this clinic!”
Common questions
Will the clinic change my warfarin dose?
The test provides the INR result. Dose decisions remain with your anticoagulation clinician unless you have booked a separate clinical review.
Do I need to fast?
Fasting is not required. Bring your current warfarin dose, anticoagulation record and medication list.
Can a doctor go through my result with me?
A private GP consultation is £150, and a follow-up consultation for existing patients is £100. The doctor reviews the result alongside your symptoms and agrees the next step.
