Protime Stability Study
Traditionally, protime procedure manuals usually state that specimens for protime testing may be stored at room temperature up to 24 hours if the collection tube remains unopened. Recently our laboratory undertook a study to determine if the protime remained stable after specimen tubes were opened.
Twenty patient specimens were initially run as usual on a Sysmex analyzer, then recapped, stored at room temperature, and reran after 24 hours. The original protime values ranged from 12 to 48 seconds and INR ranged from 1.0 to 5.8. Protime did not increase more than 2 seconds in any specimen and INR did not change more than 0.1. This study demonstrated that protimes can be reliably run on specimens that have been previously uncapped.
