Prothrombin Time
Private Prothrombin Time testing in London for £58, measuring one blood-clotting marker with results expected in around 1–2 days.
Turnaround time
1-2 business days
Biomarkers count
1
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Overview of the Prothrombin Time Test
The Prothrombin Time blood test measures how long it takes blood plasma to form a clot through the extrinsic and common coagulation pathways.
The test assesses 1 coagulation biomarker: Prothrombin Time.
Prothrombin Time is commonly abbreviated to PT.
The result is usually reported in seconds and may also be converted to an International Normalised Ratio, or INR, particularly when Warfarin treatment is being monitored.
PT reflects the activity of several clotting factors, including Factors I, II, V, VII and X.
Many of these proteins are produced by the liver.
Several are also dependent on Vitamin K.
A prolonged Prothrombin Time can therefore occur when clotting-factor activity is reduced because of liver dysfunction, Vitamin K deficiency, anticoagulant treatment or selected inherited and acquired coagulation disorders.
Warfarin intentionally prolongs the PT/INR by reducing production of Vitamin K-dependent clotting factors.
In people taking Warfarin, the appropriate INR target depends on why anticoagulation has been prescribed.
A result that is appropriate for somebody receiving Warfarin would usually be abnormal in somebody who is not anticoagulated.
Prothrombin Time is often interpreted alongside Activated Partial Thromboplastin Time, Fibrinogen, Platelet Count and liver-function tests.
The test does not provide a complete assessment of every bleeding or clotting disorder.
Some coagulation conditions can occur despite a normal PT.
What Does the Prothrombin Time Test Check?
The test measures clotting time through the extrinsic and common coagulation pathways. This test measures 1 biomarker.
Prothrombin Time
Measures the time required for plasma to clot through the extrinsic and common pathways, helping assess clotting-factor activity, liver-related coagulation and Warfarin effect.
Who May Benefit From the Prothrombin Time Test?
PT testing can be useful when abnormal bleeding, anticoagulant treatment or impaired clotting-factor production is being assessed.
People taking Warfarin - PT converted to INR is routinely used to monitor Vitamin K antagonist anticoagulation.
People with unexplained bruising or bleeding - Prolonged clotting can be investigated using coagulation tests.
People with known or suspected liver disease - Reduced hepatic clotting-factor synthesis can prolong PT.
People with possible Vitamin K deficiency - Several factors assessed by PT require Vitamin K.
People preparing for selected procedures or surgery - Coagulation testing may be requested where bleeding risk needs assessment.
People with an unexplained abnormal coagulation result - Repeat or complementary testing can help characterise the problem.
People with suspected clotting-factor deficiency - PT can help determine which pathway may be affected.
People requiring monitoring after a significant medication change - Anticoagulant or interacting medicines can alter clotting.
How to Prepare
Symptoms and Reasons to Consider the Prothrombin Time Test
Abnormal coagulation can produce bleeding symptoms, although many mild PT abnormalities cause no obvious symptoms.
Easy or unexplained bruising - Reduced clotting-factor activity can increase bruising.
Prolonged bleeding from cuts - Delayed coagulation can make bleeding last longer.
Frequent nosebleeds - Recurrent bleeding can justify coagulation assessment.
Heavy menstrual bleeding - Coagulation abnormalities are one possible contributor.
Bleeding after dental work or surgery - Excessive procedural bleeding can raise suspicion of a clotting disorder.
Abnormal liver tests - PT can provide information about hepatic clotting-factor synthesis.
Warfarin treatment - Regular INR monitoring is required to maintain treatment within the prescribed range.
Heavy active bleeding, vomiting blood, black stools, significant head injury while anticoagulated or uncontrolled bleeding requires urgent medical assessment.
Do not change a Warfarin dose independently on the basis of a private result.
How to Prepare for the Prothrombin Time Test
Fasting :: Fasting is not required.
Hydration :: Maintain normal hydration before the appointment.
Warfarin :: Take Warfarin exactly as prescribed unless the anticoagulation team has given different instructions.
Medication :: Provide a complete medication list, including anticoagulants and recent antibiotics.
Vitamin K supplements :: Record Vitamin K-containing supplements or significant changes in dietary Vitamin K intake.
Liver disease :: Provide relevant liver diagnoses and recent liver-function results.
Bleeding history :: Tell the clinician about abnormal bruising, nosebleeds or previous surgical bleeding.
Sample collection :: The citrate blood tube must be filled correctly because underfilling can distort coagulation results.
L@@@
Do not stop anticoagulant medication solely for testing unless specifically instructed by the prescribing clinician.
Accurate citrate-tube filling and timely laboratory processing are important for reliable coagulation testing.
How to Book Your Prothrombin Time Test
The Prothrombin Time test can be booked privately for coagulation assessment.
Choose the Prothrombin Time
Select the individual PT blood test online.
Select your sample collection option
Choose an in-clinic blood draw or professional home or hotel phlebotomy where timely sample transport can be maintained.
Attend your appointment
A trained healthcare professional collects the required citrate blood sample.
Laboratory analysis
Your plasma undergoes measurement of Prothrombin Time, with INR reporting where applicable.
Receive your results securely
Your authorised result is delivered securely and can be interpreted alongside other coagulation and liver investigations.
When Will I Receive My Results?
The current London Blood Tests turnaround for Prothrombin Time is approximately 1–2 days after laboratory receipt.
The sample undergoes coagulation analysis, quality-control procedures and result authorisation.
Urgent anticoagulation monitoring may require a dedicated clinical pathway rather than routine private testing.
Understanding Your Results
A normal PT means clot formation through the measured coagulation pathways occurred within the laboratory's expected interval.
A prolonged PT means clot formation took longer than expected.
Possible causes include Warfarin therapy, Vitamin K deficiency, liver dysfunction or clotting-factor deficiency.
The INR standardises Prothrombin Time between laboratories.
For somebody not taking Warfarin, INR is usually close to approximately 1.
People taking Warfarin have a deliberately higher therapeutic INR target determined by the reason for anticoagulation.
A mildly abnormal value should not be interpreted without medication history and the wider coagulation profile.
PT can also become markedly prolonged in serious liver dysfunction or disseminated coagulation disorders.
Why Book With London Blood Tests?
London Blood Tests provides private Prothrombin Time testing for coagulation and anticoagulation assessment.
Measures blood-clotting time - PT assesses the extrinsic and common coagulation pathways.
Relevant to Warfarin monitoring - INR is derived from PT for Vitamin K antagonist treatment.
Useful in bleeding assessment - Prolonged clotting can contribute to abnormal bleeding.
Relevant to liver disease - The liver produces many of the clotting factors assessed.
Can identify Vitamin K-related abnormalities - Vitamin K deficiency can prolong PT.
Can complement a wider coagulation screen - APTT and Fibrinogen provide additional information.
Professional blood collection - Correct citrate-tube collection is essential.
Clear pricing - The Prothrombin Time test costs £58.
Private Prothrombin Time Blood Test in London
London Blood Tests provides private Prothrombin Time testing for people requiring assessment of blood coagulation.
The test costs £58 and measures 1 coagulation biomarker.
Results are expected approximately 1–2 days after laboratory receipt.
The result should be interpreted according to medication use, liver status and whether anticoagulation treatment is being monitored.