Interestingly, Tripodi has also written in JTH (doi:1111/jth. MANNUCCI Journal of Thrombosis and Haemostasis, 6: 243≢48. See The international normalized ratio to prioritize patients for liver transplantation: problems and possible solutions A. For the INR to be used in liver disease and other groups of patients one would have to be sure that the ISI as determined on warfarinised patients, is also applicable to these other groups of patients and there is evidence that this is not the case. As we know, the ISI is determined by performing PTs on a group of stabilized warfarinised patients and some normals calibrating against one of the International thromboplastin standards. With respect to Dr Brace, the INR is calculated mathematically but the calculation is based on 2 measured components, the PT and the ISI. With respect to Dr Brace, the INR is calculated mathematical It is true that most clinicians who have entered the profession in the past 20 years only know the test by “ INR,” and, in fact, the INR is nothing more than a ratio computed directly from the PT in seconds, so why not just use it? I’d like to hear from our participants on this subject. However, I’ve never been able to refute his argument, presented above with eloquence. To screen for extrinsic pathway coagulopathies, we must use and report the PT in seconds compared to our locally developed PT reference interval. Brace and I have had this discussion on one or two occasions in the past, and I’ve stubbornly hewed (hewn?) to “conventional wisdom,” asserting that the INR was only developed for monitoring Coumadin. What would you do? There is no way that an INR upper limit of 1.1 would ever work.įrom Geo: Dr. We have 3 Stago instruments in 2 locations – the Satellite is at an off-site. We just completed our evaluation of a new lot of PT reagent. I simply adjusted the PT in seconds to match the INR. When we did our last normal range verification, it comes as no surprise that our normal range in seconds did not match the upper and lower limits based on the INR. Personally, I would be just as happy with an INR upper limit of 1.2 and will lobby for that with the newest lot of reagent (see below). BTW, the upper limit of 1.25 was based on clinician input because they were unhappy chasing clinically irrelevant “abnormal” results. (Yes, we still report both, but I don’t know for how much longer). I bring this up because during my most recent CAP inspection at Edward, the CAP inspectors had a fit about the upper end of our normal range in seconds (which corresponded to an INR of 1.25). This causes no end of grief because it is almost impossible to explain to clinicians why one result is flagged as normal and the other as abnormal. If you adopt as normal an INR of 0.9–1.2, but determine independently the reference interval for the PT in seconds, you invariably get situations in which the INR is normal but the PT in seconds is not, or vice versa. If someone would really need to have a normal reference interval for the PT in seconds (and I don’t know why they would), the upper end of the normal range would be the PT in seconds that correlates to an INR of 1.2 and the lower end of the reference interval would be the PT in seconds that corresponds to an INR of 0.9. Isn’t the INR a “standardized” assay? We say it is, and that every laboratory that reports INR should match every other laboratory that reports INR.

We don’t do normal reference intervals for cholesterol, we just adopt them based on ATP guidelines because cholesterol is a “standardized” assay. I think that the PT in seconds should be eliminated and we should view the INR in the same way we view cholesterol. We know that the general consensus is that the international normalized ratio ( INR) is considered normal to at least 1.2 (maybe 1.25 if you calculate to 2 decimal points). We should no longer have to do a normal range for the PT in seconds. Here is my view on prothrombin time ( PT) in seconds. Larry Brace, Edward Hospital, Naperville, IL: I need an opinion.

Inr normal range vs therapeutic