Протромбиновое время (ПВ)/PT
Code:3003
| Includes | Протромбин по Квику Международное нормализованное отношение (МНО) |
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Analysis details
Methodology
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Expected Turnaround Time
1 day
Special Instructions
- For infants younger than 1 year, avoid feeding for 30–40 minutes before the blood draw.
- For children 1–5 years old, fast for 2–3 hours prior to collection.
- For older children and adults, fast for 12 hours before the test; plain, noncarbonated water is permitted.
- Avoid physical exertion and emotional stress for at least 30 minutes before sampling.
- Do not smoke during the 30 minutes preceding specimen collection.
How to use
Coagulogram No. 1 (Prothrombin [Quick], INR) measures the prothrombin time and reports results as the International Normalized Ratio (INR) and prothrombin activity by Quick. The assay supports management of therapy with vitamin K antagonists (eg, warfarin) by helping balance anticoagulation with bleeding risk. In addition, the test is used to assess factor VII activity as part of evaluating the extrinsic pathway of coagulation. Common synonyms include prothrombin time (PT), protime, and international normalized ratio.
Limitations
Prothrombin time (PT) evaluates the extrinsic pathway of coagulation. In this panel, results are reported as prothrombin by Quick and as the International Normalized Ratio (INR). Prothrombin by Quick expresses clotting activity as a percentage of normal derived from a calibration curve generated with dilutions of reference plasma. Although not standardized across reagents, the Quick percentage remains useful for assessing components of the extrinsic pathway such as factor VII. INR is a standardized metric calculated as the patient’s PT divided by the mean normal PT, raised to the international sensitivity index (ISI) of the thromboplastin reagent. Because INR adjusts for reagent sensitivity, it enables comparison of anticoagulation intensity across laboratories and instruments. Clinically, INR is used to gauge the degree of hypocoagulation during therapy with vitamin K antagonists (eg, warfarin and related agents), independent of the specific thromboplastin in use. Therapeutic targets are defined by clinical indication under international guidance and permit consistent monitoring and dose titration.
| Reference interval |
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|---|---|---|---|---|---|
| Indications | Therapeutic monitoring and dose adjustment during treatment with indirect anticoagulants (vitamin K antagonists, including warfarin)., Screening evaluation of the hemostatic system with emphasis on the extrinsic coagulation pathway. |
Specimen Requirements
| Specimen | Plasma |
|---|---|
| Container | Light Blue Top (3.2% Sodium Citrate) |