29 January 2025
: Case report 
Impact of Lupus Anticoagulant on INR Using Recombinant Prothrombin Time Reagent
Unusual clinical course, Challenging differential diagnosis, Unusual or unexpected effect of treatment, Diagnostic / therapeutic accidents, Clinical situation which can not be reproduced for ethical reasons
Fatmawati Kamal
ABCDEF 1*, Halimatun Radziah Othman ABCDEF 2
DOI: 10.12659/AJCR.945579
Am J Case Rep 2025; 26:e945579
Table 2. PT mixing test at our laboratory.
| Our laboratory | Reference laboratory | |||
|---|---|---|---|---|
| Method | Photo-optical | |||
| Coagulation analyzer | Sysmex CS-2500 | Intrumentation Laboratory (IL) | ||
| Werfen ACL Top 550 CTS | ||||
| PT Reagent | Siemens Dade Innovin | Werfen HemosIL | ||
| RecombiPlasTin 2G assay | ||||
| Date | 24.1.22 | 27.1.22 | ||
| Rosner Index – (Mix PTT-NP PTT)/Patient PTT ×100. Rosner index of ≤10, indicates correction, and ≥15 is no correction. RI 11–14 is inconclusive and the mixing test should be repeated. ND – not done. | ||||
| Patient’s results | Reference range | Patient’s results | Reference range | |
| Prothrombin time (PT) (sec) | 37.2 | 9.3–10.8 | 13.8 | 10.3–12.7 |
| International normalized ratio (INR) | 3.8 | <1.2 | 1.2 | 1.0–1.1 |
| FVII antigen | 78.4% | 50–129% | ||
| FVII inhibitor | No inhibitor | |||
| PT mixing test | ||||
| Prothrombin time (PT) (sec) | 36.9 | |||
| Normal pool plasma (NPP) PT | 12.4 | |||
| PT immediate mixing test (1: 1 mix) | 26.8 | |||
| Rosner Index | 39 | |||
| APTT mixing | ND | |||
| Rosner Index – (Mix PTT-NP PTT)/Patient PTT ×100. Rosner index of ≤10, indicates correction, and ≥15 is no correction. RI 11–14 is inconclusive and the mixing test should be repeated. ND – not done. | ||||