Setting Up the Experiment
Required Configuration
- Reagent ISI — The International Sensitivity Index from the current reagent lot's package insert. Must be a positive number (typically 1.0–1.4 for modern thromboplastin reagents). The ISI is lot-specific and must be updated each time the reagent lot changes.
- Total Number of Samples — The number of normal subjects in the study (20–500). Must be entered before data upload and must match the number of PT values provided.
- PT Lower Limit — The lower boundary of the PT reference interval in seconds (e.g., 10.0 s). Established by the laboratory's reference interval study or adopted from the reagent manufacturer's package insert.
- PT Upper Limit — The upper boundary of the PT reference interval in seconds (e.g., 14.0 s). Must be greater than the PT Lower Limit.
- Compute INR from PT — When checked (default), INR values are computed from PT values using INR = (PT / NPM)^ISI and INR reference limits are derived from the PT limits. When unchecked, INR values and limits must be provided directly.
Optional Fields
The following fields are for documentation and traceability only — they do not affect the calculations:
- Operator — The person performing the study
- Reagent Source — The reagent manufacturer or vendor
- Reagent Lot Number — The specific lot being characterized
- Reagent Expiration Date — The lot expiration date (format: YYYY-MM-DD)
Data Entry
For each normal subject, enter:
| Field | Description |
|---|---|
| Sample ID | A unique identifier for the subject (e.g., sequential numbering). Each sample must have a distinct ID. |
| PT Value | The raw Prothrombin Time in seconds for this subject. Must be a positive number. INR is computed from this value when the checkbox is enabled. |
Data can be entered manually or uploaded via CSV. See the data upload guide within the module for the expected CSV format.