Setting Up the Experiment
Required Configuration
- ISI — The International Sensitivity Index for the current reagent lot, from the reagent's package insert. This must be the same value that was programmed into the analyzer. Enter it exactly as it appears in the package insert, preserving decimal precision.
- Normal Patient Mean PT — The geometric mean PT established for the current reagent lot on this analyzer, from the Geometric Mean & VRI study for this lot. This must be the value that was (or should have been) programmed into the analyzer.
- Number of Specimens — The number of PT/INR pairs to verify (3–5). A minimum of 3 specimens is required; 5 is recommended for a more complete check across the measurement range.
Optional Fields
- Operator — The person performing the verification
- Reagent lot number — The lot being verified
- Reagent expiration date — For documentation purposes
Data Entry
For each specimen, enter both values exactly as reported by the analyzer:
| Field | Description |
|---|---|
| Sample ID | A unique identifier for each specimen (e.g., sequential numbering or accession number). |
| ProTime (PT) | The Prothrombin Time in seconds as reported by the analyzer for this specimen. Used as the input to the INR recalculation. |
| INR | The INR value as reported by the analyzer for this specimen. This is the value being verified against the independently calculated INR. |
Specimen selection: Include specimens that span the clinically relevant INR range — ideally one near normal (INR ~1.0), one in the therapeutic anticoagulation range (INR 2.0–3.5), and one at a higher value if available. This confirms that the analyzer's calculation is correct across the range, not just at a single concentration.