Activated Protein C Resistance
Private Activated Protein C Resistance blood test in London for £140, assessing one clotting marker with results in approximately 4 business days.
Turnaround time
4 business days
Biomarkers count
1
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Overview of the Activated Protein C Resistance
The Activated Protein C Resistance blood test is a specialist functional coagulation test used to assess how effectively activated protein C helps regulate blood clotting.
Activated protein C, commonly abbreviated to APC, forms part of one of the body's natural anticoagulant pathways. Working with its cofactor Protein S, APC helps limit excessive clot formation by inactivating activated clotting factors Va and VIIIa.
When Factor V does not respond normally to activated protein C, this regulatory mechanism becomes less effective. This is known as activated protein C resistance, or APC resistance, and it can be associated with an increased tendency towards venous blood clot formation.
The test contains 1 biomarker: Activated Protein C Resistance.
The most common inherited cause of APC resistance is Factor V Leiden, a variant in the F5 gene that alters Factor V so that it is less readily inactivated by activated protein C. However, APC resistance and Factor V Leiden are not identical. A functional APC resistance assay evaluates the behaviour of the clotting system, while a Factor V Leiden genetic test looks directly for a specific DNA variant.
Other inherited Factor V variants and acquired factors can occasionally produce an abnormal APC response. Pregnancy, oestrogen exposure, lupus anticoagulant and changes in other coagulation proteins may influence APC sensitivity depending on the clinical circumstances and assay method.
This makes the test useful as part of a thrombophilia investigation, particularly following venous thromboembolism or where a clinician suspects an inherited clotting tendency.
An abnormal result does not mean that a blood clot will definitely occur. Conversely, a normal APC Resistance result does not exclude other inherited or acquired thrombophilias.
Results should therefore be interpreted alongside personal and family history, previous clotting events, medication, other coagulation tests and, where appropriate, Factor V Leiden genetic analysis.
What Does the Activated Protein C Resistance Test Check?
This test measures 1 biomarker.
Activated Protein C Resistance
Functionally assesses how the blood clotting system responds to activated protein C. A reduced response may indicate APC resistance, most commonly associated with the inherited Factor V Leiden variant, although other inherited or acquired influences can also affect the result.
Who May Benefit From the Activated Protein C Resistance Test?
This test may be suitable for people whose personal history, family history or previous clotting investigations suggest that an inherited thrombophilia should be considered.
Previous unexplained deep vein thrombosis - APC resistance may form part of a thrombophilia assessment following a DVT, particularly when the event occurred at a relatively young age or without a strong temporary trigger.
Previous pulmonary embolism - Investigation may be considered following a PE where an inherited clotting tendency is clinically suspected.
Recurrent venous thrombosis - More than one episode of venous thromboembolism may prompt specialist assessment of inherited and acquired risk factors.
Blood clot at a relatively young age - Earlier-than-expected thrombosis can increase clinical suspicion of an inherited thrombophilia.
Strong family history of venous thromboembolism - A pattern of DVT or pulmonary embolism among close relatives may make targeted clotting investigations relevant.
Family history of Factor V Leiden - Functional APC testing may provide useful information, although direct genetic testing may be preferable when a specific familial mutation is already known.
Thrombosis in an unusual clinical setting - Selected patients with unusual or unexplained clotting events may be referred for specialist thrombophilia testing.
Previous abnormal coagulation investigation - APC Resistance may provide additional functional information where earlier tests suggest an abnormal clotting tendency.
Specialist-requested thrombophilia testing - The test can be arranged privately when recommended by a haematologist, GP or another suitably qualified clinician.
How to Prepare
The current specialist laboratory requires a citrate sample with specific processing requirements. If transport to the laboratory is delayed, the plasma requires specialist separation and freezing procedures.
These are laboratory and phlebotomy handling requirements rather than steps you need to perform yourself. However, they mean that collection arrangements should be confirmed before booking, particularly for a home or hotel appointment.
Do not stop anticoagulation simply to obtain an APC Resistance result. If medication could interfere with the assay, the safest testing strategy should be discussed with a clinician or laboratory.
Symptoms and Reasons to Consider the Activated Protein C Resistance Test
Activated Protein C Resistance itself generally does not cause symptoms unless a blood clot develops. Testing is therefore usually prompted by medical or family history rather than by day-to-day symptoms.
Previous deep vein thrombosis - A DVT commonly develops in a deep vein of the leg and may present with pain, swelling, tenderness or warmth.
Previous pulmonary embolism - A PE occurs when a clot travels to the lungs and may cause sudden breathlessness, chest pain or coughing up blood.
Repeated unexplained blood clots - Recurrent thrombosis can prompt assessment for inherited and acquired clotting risk factors.
Blood clot without an obvious temporary trigger - Thrombosis occurring without recent surgery, prolonged immobility or another clear provoking factor may lead to further investigation.
Clotting during pregnancy or the postpartum period - Pregnancy itself increases venous thrombosis risk, and additional inherited risk factors may sometimes be investigated following specialist assessment.
Clot associated with oestrogen-containing medication - Combined hormonal contraception or some forms of hormone therapy can increase venous clot risk, particularly when other risk factors coexist.
Close relative with Factor V Leiden - Family history may prompt discussion about whether functional or genetic testing is appropriate.
Strong family history of DVT or pulmonary embolism - Multiple affected relatives can suggest an inherited contribution to thrombosis risk.
Previous borderline thrombophilia results - Functional APC testing may contribute additional information depending on what has already been measured.
A clinician has recommended thrombophilia assessment - APC Resistance may form one part of a broader investigation following an appropriate clinical risk assessment.
APC resistance should not be used as a general screening test simply because someone is considering contraception, pregnancy or hormone treatment. Whether thrombophilia testing is appropriate depends on personal clotting history, family history and clinical circumstances.
A positive APC Resistance result indicates increased functional resistance to activated protein C but does not establish that a person currently has a blood clot.
New unilateral leg swelling or pain, sudden unexplained breathlessness, chest pain, coughing up blood, collapse or severe deterioration can indicate DVT or pulmonary embolism and requires urgent medical assessment rather than routine outpatient thrombophilia testing.
How to Book Your Activated Protein C Resistance
Booking your Activated Protein C Resistance test with London Blood Tests is simple, although this specialist coagulation sample requires appropriate handling.
Choose the Activated Protein C Resistance
Select the Activated Protein C Resistance test online and review the included specialist coagulation biomarker before booking.
Select your sample collection option
Choose an in-clinic blood draw (+£35) or a home or hotel phlebotomy visit (+£60) where available and where the time-sensitive citrate sample processing and transport requirements can be met.
Attend your appointment
A trained professional will collect the required citrate blood sample and arrange handling according to the specialist coagulation laboratory requirements.
Laboratory analysis
Your sample is sent to the laboratory, where a functional coagulation assay assesses the response to activated protein C.
Receive your results securely
Your result is sent securely by email, ready to review yourself or discuss with a GP, haematologist or other suitably qualified healthcare professional.
When Will I Receive My Results?
The customer-facing turnaround time for the Activated Protein C Resistance test is approximately 4 business days after the laboratory receives the correctly prepared sample.
The specialist laboratory currently lists approximately 3 laboratory days for the underlying APCR assay, while London Blood Tests provides a 4-day customer turnaround to allow for processing and reporting.
Your result is sent securely by email once specialist analysis and laboratory authorisation are complete.
Because coagulation samples have strict handling requirements, sample transport issues, repeat analysis or specialist laboratory review can occasionally extend the expected turnaround.
Understanding Your Results
The Activated Protein C Resistance test typically assesses how much a clotting measurement changes when activated protein C is introduced, with the laboratory reporting an APC resistance ratio or its own interpretive result.
A reduced APC response or low APC Resistance ratio may indicate activated protein C resistance. The most common inherited cause is Factor V Leiden.
Factor V Leiden changes Factor V so that activated protein C cannot inactivate it as efficiently as usual. This allows activated Factor V to remain active for longer and can increase thrombin generation and venous clotting tendency.
An abnormal functional result does not automatically prove that Factor V Leiden is present. Other Factor V variants and acquired influences can occasionally produce APC resistance, and assay interference also needs to be considered.
For this reason, Factor V Leiden genetic testing may be recommended following an abnormal or equivocal functional result. Genetic testing directly examines the F5 gene and is not affected by anticoagulant medication in the same way as a functional coagulation assay.
A normal APC Resistance result means the assay has not demonstrated abnormal resistance under the conditions tested. It does not exclude other thrombophilias such as Prothrombin G20210A, antiphospholipid syndrome, Protein C deficiency, Protein S deficiency or Antithrombin deficiency.
Medication is particularly important when interpreting functional coagulation tests. Direct oral anticoagulants, heparin and other anticoagulant effects can interfere with some APC resistance methods. Lupus anticoagulant and other coagulation abnormalities can also complicate interpretation.
The exact reference interval depends on the assay used by the analysing laboratory. Your result should therefore be interpreted using the laboratory's own cut-off rather than applying a numerical threshold from another laboratory.
Most importantly, APC resistance represents a risk factor rather than a prediction that thrombosis will definitely occur. Overall clot risk depends on multiple inherited and acquired factors, including age, previous thrombosis, surgery, immobility, pregnancy, oestrogen exposure, smoking, cancer and other medical conditions.
Why Book With London Blood Tests?
Private thrombophilia testing in London - Access specialist Activated Protein C Resistance testing through London Blood Tests.
Functional clotting assessment - The assay measures how the coagulation system responds to activated protein C rather than simply looking for a genetic variant.
Relevant to Factor V Leiden investigation - Factor V Leiden is the most common inherited cause of APC resistance and genetic confirmation may be considered after an abnormal functional result.
Focused one-biomarker test - Assess APC resistance without automatically booking a larger thrombophilia profile.
Specialist coagulation laboratory analysis - The sample undergoes dedicated haemostasis testing with specific citrate sample-processing requirements.
Useful alongside other thrombophilia investigations - APC resistance can be interpreted with Factor V Leiden, Prothrombin mutation and antiphospholipid testing where clinically appropriate.
Clinic and selected home visit options - Sample collection can be arranged according to laboratory handling requirements and location availability.
Clear pricing before booking - The Activated Protein C Resistance test is priced at £140, with sample collection charges shown separately.
Private Activated Protein C Resistance Blood Test in London
London Blood Tests provides the Activated Protein C Resistance blood test in London for people who require specialist functional assessment of an inherited or acquired tendency towards abnormal blood clotting.
The test costs £140 and measures one biomarker: Activated Protein C Resistance. It is particularly relevant when Factor V Leiden or another thrombophilia is being considered following an appropriate medical assessment.
The assay requires a specialist citrate blood sample with time-sensitive processing, so collection must be arranged in a way that meets the laboratory's handling requirements. In-clinic collection is available, while home or hotel phlebotomy may be possible where appropriate transport and processing can be arranged.
An abnormal APC Resistance result does not independently diagnose Factor V Leiden or determine whether someone will develop a blood clot. Depending on the result and clinical history, a haematologist or GP may recommend Factor V Leiden genetic testing or additional thrombophilia investigations.