Lever
Lifestyle
- Regular monitoring of INR levels
- Consistent dietary vitamin K intake
- Avoiding alcohol overconsumption
Blutwerte · Marker
Quick / INR
Prothrombin Time · PT · INR · Quick-Wert
Gerinnung
- Einheit:
- ratio
The Quick / INR test quantifies the time it takes for blood to clot, specifically measuring the activity of the extrinsic and common coagulation pathways.
Reference Ranges
Reference
0.8–1.2ratio
0.8
1.2
LowNormalHigh
Reference
Unit · ratioReference ranges may vary slightly depending on the laboratory and the specific thromboplastin used.
Overview
Übersicht
The Quick / INR test, also known as Prothrombin Time (PT) or International Normalized Ratio (INR), is a critical measure of the coagulation cascade, specifically assessing the extrinsic and common pathways of blood coagulation. It evaluates the time taken for blood to clot by measuring the activity of clotting factors I, II, V, VII, and X. Clinically, this test is essential for monitoring patients on anticoagulant therapy, particularly those using vitamin K antagonists like warfarin. It helps ensure therapeutic levels are maintained to prevent thrombosis while minimizing bleeding risks. Researchers found that variations in thromboplastin reagents and coagulometer models can affect INR results, necessitating careful standardization and validation of ISI values across laboratories. For athletes and biohackers, maintaining optimal coagulation balance is crucial to avoid bleeding risks during intense physical activity or when experimenting with supplements that may affect coagulation. However, the INR is not typically used for performance enhancement or longevity but is vital for those on anticoagulant therapy. Caveats include potential interference from dietary vitamin K intake, liver function, and certain medications. Researchers observed that fasting is not required for this test, but consistent timing of sample collection is recommended to minimize variability.
Klinische Bedeutung
Elevated INR values indicate a prolonged clotting time, suggesting potential bleeding risks or effective anticoagulation therapy. Reduced INR values may indicate a risk of thrombosis or inadequate anticoagulation.
Dynamics
Trend Interpretation
Rising Values
Progressively rising INR values suggest increased bleeding risk or effective anticoagulation. Re-test within 1-2 weeks.
Falling Values
Progressively falling INR values may indicate reduced anticoagulation efficacy or increased thrombosis risk.
Re-test Interval
4 weeks if outside optimal range
Etiology
Causes — High & Low
Cause
Elevated Levels
- Vitamin K deficiency
- Liver disease
- Warfarin therapy
- Disseminated intravascular coagulation
- Factor deficiency
Cause
Low Levels
- Excessive vitamin K intake
- Hypercoagulable states
- Early stages of sepsis
- Technical error in testing
- Incorrect anticoagulant dosing
Protocol
How to Optimize
Lever
Nutrition
- Incorporate green leafy vegetables
- Maintain a balanced diet
- Limit vitamin K-rich foods if on warfarin
Lever
Supplementation
- Vitamin K supplements if deficient
Note:
Consult a healthcare provider before making dietary changes if on anticoagulant therapy.
Testing Guidelines
✓Fasting Not Required
✓Not Time-Sensitive
Testing Frequency
Frequency depends on anticoagulation therapy; typically every 1-4 weeks for those on warfarin.
Interfering Factors
- Dietary vitamin K fluctuations
- Liver dysfunction
- Certain medications
Open Research Questions
Current research suggests that there is significant variability in INR results across laboratories due to differences in ISI values and thromboplastin reagents, which complicates standardization efforts. Researchers have not yet established definitive reference ranges for INR in specific populations, particularly in patients with vitamin K deficiency or sepsis-induced coagulopathy. Unanswered clinical questions include the optimal INR targets for various patient groups and the impact of genetic factors on INR variability.
22 Research Publications
664
Total Citations
8
Human/RCT
4.1
Avg. Influence
2025
Latest
Sort
Filter
01Top
#01
Sepsis-Induced Coagulopathy: An Update on Pathophysiology, Biomarkers, and Current Guidelines.
ReviewInfluence9.0
153
This study updated the understanding of sepsis-induced coagulopathy (SIC) and its biomarkers. Researchers found that significant interactions between inflammation and coagulation occur in sepsis, leading to a prothrombotic state initially, followed by hypocoagulability in late stages. The study emphasizes the need for early identification of SIC to allow for timely therapeutic interventions.
02Top
#02
Standardization of Prothrombin Time/International Normalized Ratio (PT/INR).
ReviewInfluence8.0
121
This study examined the standardization of prothrombin time (PT) and international normalized ratio (INR) in clinical laboratories. Researchers found that despite efforts to harmonize INR results across laboratories, significant variability still exists, which can impact patient management. The study emphasizes the importance of appropriate verification and validation of ISI values to reduce discrepancies in INR reporting.
03Top
#03
Laboratory testing of anticoagulants: the present and the future.
ReviewInfluence6.0
111
This study provided an update on laboratory testing for anticoagulants, including PT/INR and APTT. Researchers found that while newer anticoagulants may not require routine monitoring, laboratory testing remains essential for certain situations. The study highlighted the need for proactive development of testing strategies in pathology laboratories.
04
#04
Standardization of prothrombin time for laboratory control of oral anticoagulant therapy.
Review
61
This study focused on the standardization of prothrombin time (PT) for monitoring oral anticoagulant therapy. Researchers found that using the WHO calibration model improves the consistency of INR results across laboratories. The study highlights the importance of sensitive reagents and local calibration to enhance monitoring accuracy.
05
#05
Laboratory investigations for bleeding disorders.
HumanInfluence3.0
48
This study explored the effectiveness of bleeding disorder panels that include PT/INR and other tests. Researchers found that while these tests had acceptable specificity, their sensitivity to clinically significant abnormalities was low. The study highlighted the need for expanded panels to improve the detection of bleeding disorders.
06
#06
Coagulation in Liver Disease.
Review
39
This study reviewed the role of the liver in hemostasis and its impact on coagulation tests. Researchers observed that PT and aPTT do not fully reflect the coagulation status in liver disease patients. The review highlights the need for better assessments of bleeding and thrombosis risks in these patients.
07
#07
International Normalized Ratio Is Significantly Elevated With Rivaroxaban and Apixaban Drug Therapies: A Retrospective Study.
HumanInfluence2.0
33
This study assessed the impact of direct factor Xa inhibitors, rivaroxaban and apixaban, on prothrombin time (PT) and INR in hospitalized patients. Researchers found that both drugs significantly elevated INR levels, with rivaroxaban causing a greater increase than apixaban. The study concluded that these drugs' effects on INR should be interpreted with caution due to variability in PT assay sensitivity.
08
#08
Clinical Evaluation of Bleeding and Bruising in Primary Care.
ReviewInfluence1.0
27
This study evaluated the clinical assessment of bleeding and bruising in primary care. Researchers found that initial laboratory tests, including PT and PTT, are crucial for diagnosing bleeding disorders. The study emphasizes the importance of thorough patient history and examination to guide further testing.
09
#09
Activated Partial Thromboplastin Time and Prothrombin Time Mixing Studies: Current State of the Art.
ReviewInfluence2.0
25
This study reviewed the current state of mixing studies used to investigate prolonged activated partial thromboplastin time (aPTT) and prothrombin time (PT). Researchers found that these tests can differentiate between factor deficiencies and inhibitors, but lack standardization in testing protocols and interpretation. The review highlights common indications for mixing tests and factors that can affect their performance.
10
#10
Coagulation.
Review
19
This study provided an overview of the limitations of PT and APTT tests in assessing the haemostatic system. Researchers found that these tests only evaluate the coagulation protein compartment and must be interpreted with caution in clinical contexts like anticoagulant monitoring and bleeding symptoms. The study suggests that routine preoperative screening using these tests is often unwarranted without abnormal bleeding history.
Clinical Trials (6)
6
Total Trials
2,494
Total Enrolled
Combining Fasting and Fibre Interventions to Optimise Their Gut Microbiome-mediated Health Benefits
NCT07691736NOT_YET_RECRUITING
Sponsor
Buchinger Wilhelmi Development & Holding GmbH
Enrollment
75
Started
2026
Primary outcome
Abundance of butyrate-producing gut bacteria
FastingDietary FibreGut MicrobiomeMetabolism ChangesOverweight , Obesity
Adaptive Platform Trial for Personnalisation of Sepsis Treatment in Children and Adults: a Multi-national, Treatable Traits-guided, Adaptive, Exploratory, Bayesian Basket Trial
Sponsor
Assistance Publique - Hôpitaux de Paris
Enrollment
2,000
Started
2026
Primary outcome
All-cause mortality
Sepsis
UNDERSTANDING THE T-CELL AND B-CELL RECEPTOR REPERTOIRE IN CHILDREN AND YOUNG ADULTS WITH ANTI-DRUG ANTIBODIES AGAINST PEG ASPARAGINASE
NCT07499336NOT_YET_RECRUITING
Sponsor
Aarhus University Hospital
Enrollment
45
Started
2026
Primary outcome
Identify biomarkers in children and young adults with ALL with hypersensitivity to PEG-asparaginase.
Acute Lymphoblastic Leukaemia - Category
Understanding the 'Durable Effect' Concept of B-cell Modulating Therapies
NCT06586177RECRUITING
Sponsor
Heinrich-Heine University, Duesseldorf
Enrollment
100
Started
2021
Primary outcome
Change from baseline in the peripheral immune cell profile
Relapsing-remitting Multiple Sclerosis
Proof-of-concept Trial of IVA337 in Diffuse Cutaneous Systemic Sclerosis
Sponsor
Inventiva Pharma
Enrollment
145
Started
2015
Primary outcome
Measurement of skin thickness by the Modified Rodnan Skin Score (MRSS)
Scleroderma, DiffuseDiffuse Cutaneous Systemic Sclerosis
Intermittent Calorie Restriction, Insulin Resistance, and Biomarkers of Brain Function
NCT02460783COMPLETED
Sponsor
National Institute on Aging (NIA)
Enrollment
129
Started
2015
Primary outcome
Mean Change in Neuron-Derived Extracellular Vesicle (NDEV) Phosphorylated Serine312-insulin Receptor Substrate-1 (pS312-IRS-1)
Alzheimer's DiseaseObesityDiabetes Mellitus
Publication Trend
Research publications about Quick / INR over time
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