Someone please explain pTT and pt! I don't get it!

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Can someone please give me a dumbed down, simple explanation of pTT and pt??? For some reason I am totally stuck on these two things. I get that they are tests for clotting time, but I don't get the difference between the two and how they relate to real life nursing.

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Just a tip to tell which ones goes with which the "tt" in ptt looks like an H!!!!!! so it's heparin ... =) =)

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Specializes in Emergency, Critical Care (CEN, CCRN).

PT and INR (of which INR is just a standardized version of PT) measure the extrinsic pathway of coagulation, which is blocked by Coumadin and accelerated by Vitamin K. Since the PT lab test is done with a biologically derived reagent whose activity isn't the same from batch to batch, the lab result must be corrected by an "activity factor"; that correction is what gives you the INR. Hence, in clinical practice it's only the INR that you really care about. A normal INR should be 0.8-1.2; a patient on Coumadin should have an INR in the 2.0-3.0 range. Anything over 3 is cause for concern, and over 5 is dangerously anticoagulated (get orders for Vitamin K and possibly cryoprecipitate or FFP as well).

PTT (and by extension aPTT) is a measure of the intrinsic pathway, which is blocked by heparin and faulty in hemophilia. A normal PTT is 25-35 seconds; a patient on heparin should have a PTT 1.5-2x the reference range. Anything over that is dangerously anticoagulated, and if heparin is involved, you should be looking for a protamine order.

Hope this helps!

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Just a tip to tell which ones goes with which the "tt" in ptt looks like an H!!!!!! so it's heparin ... =) =)

and PT boats go to war (warfarin-coumadin)

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