I believe the DRVVT (Dilute Russell's Viper Venom Time) is one of the tests used to screen for the Lupus Anticoagulant.
A while back I posted a question about my wife potentially having 'seronegative APS'. I was going through her lab tests the other day and noticed her DRVVT screen test was 42 seconds. After doing some research, it seems like some labs would consider this 'borderline', but hers would only do the 'reflex testing' if it was over 45.
I'm not too familiar with this test. Is this something that's standardized between laboratories? If so, why do different labs have different ranges?
Do you have any thoughts or further reading material?