Understanding Your Coagulation Test Results
Direct Answer
Your question lacks critical context about what "that" refers to, making it impossible to determine if a specific factor caused your INR of 1.4, PT of 15.3 seconds, and elevated aPTT. However, I can provide guidance on what these values mean and common causes of such patterns.
Interpretation of Your Results
INR and PT Values
- Your INR of 1.4 is mildly elevated above the normal range (typically 0.9-1.1), though it falls below the therapeutic anticoagulation target of 2.0-3.0 used for conditions like atrial fibrillation or venous thromboembolism 1.
- Your PT of 15.3 seconds is mildly prolonged compared to typical normal ranges (11.5-14.5 seconds) 1.
- For warfarin therapy, an INR ≤1.4 is considered acceptable for certain procedures like neuraxial anesthesia 1.
aPTT Elevation
- An elevated aPTT in combination with mildly elevated INR/PT suggests several possibilities 1:
- Anticoagulant medication effect (heparin, warfarin, or novel oral anticoagulants)
- Coagulation factor deficiencies
- Lupus anticoagulant or other inhibitors
- Liver disease
- Vitamin K deficiency
Common Causes to Consider
Medication-Related Causes
- Warfarin can cause both INR and aPTT elevation, though your INR of 1.4 represents subtherapeutic anticoagulation if you're taking warfarin 2.
- Heparin (unfractionated) directly prolongs aPTT and can also affect PT/INR; therapeutic aPTT targets are typically 1.5-2.5 times control (45-75 seconds) 1.
- Novel oral anticoagulants (dabigatran, rivaroxaban) can prolong both INR and aPTT, though standard tests are not ideal for monitoring these drugs 3, 4.
Non-Medication Causes
- Liver disease impairs synthesis of clotting factors, prolonging both PT and aPTT 2.
- Vitamin K deficiency primarily affects PT/INR but can also impact aPTT 2.
- COVID-19 infection can cause coagulopathy with prolonged PT (though typically modest: 15.5 seconds in non-survivors vs 13.6 seconds in survivors) 1.
- Disseminated intravascular coagulation (DIC) causes prolongation of multiple coagulation parameters 1.
Critical Pitfalls
Testing Considerations
- INR and aPTT results vary significantly between laboratories and reagents, with coefficient of variation particularly high for novel anticoagulants 4, 5.
- Sample handling matters: plasma samples for PT/INR remain stable for 24 hours refrigerated, but aPTT samples deteriorate after 12 hours even when refrigerated 6.
- If you're on heparin, blood for PT/INR should be drawn at least 5 hours after IV bolus, 4 hours after stopping continuous infusion, or 24 hours after subcutaneous injection 2.
Clinical Context Required
To determine what caused your specific results, you must identify:
- Current medications (especially anticoagulants, antibiotics, or supplements)
- Recent illnesses or infections
- Dietary changes (vitamin K intake)
- Liver or kidney disease
- Recent procedures or surgeries
- Bleeding symptoms
Next Steps
Contact your healthcare provider immediately to:
- Review your complete medication list and recent exposures
- Determine if repeat testing is needed
- Assess for bleeding risk given your coagulation abnormalities
- Consider additional testing (fibrinogen, platelet count, specific factor assays, or liver function tests) based on clinical context 1
Without knowing what "that" refers to in your question, I cannot definitively state causation, but the pattern suggests either medication effect, mild coagulation factor deficiency, or early liver dysfunction.