There’s been a lively discussion in the comments section attached to a September 18, 2008 post entitled Reference Intervals for Pediatric PTs. One of our active participants, “nomorefede” from Argentina is supporting the use of the prothrombin time ratio (PTR) in place of prothrombin time in seconds with the PT is used for coagulopathy screening and not warfarin monitoring. He provides a formula and insists the PT reference interval should be provided as a PTR. Do you use the PTR? Do you advocate for the PTR in preference to the PT in seconds? I’d like to learn more about this. Geo.