PTT & PT theraputic level?

[moliuchick, RN]

I am going to take the NCLEX this coming Monday and I am still very confuse about the PTT & PT level.

This is what I know:

PTT is used with heparin therapy. norm PTT is 20-45 sec and if you are on heparin the theraputic level should be 1.5-2.5 times 20-45 sec that means it takes longer time to have blood to clot.

PT is used with Coumadin therapy. Norm is around 9.6-12 sec and if you are taking Coumadin, the therapeutic level should be 1.5-2.5 times 9.6-12 sec?

Am I right? How come different books said different NORM?

Then what about INR? is it always used with Coumadin and heparin therapy?

Is the Norm for INR 2-3 when you are on blood thinner? Or is 2-3 Norm for normal person without the blood thinner.

Sorry that this is a dumb question but this is all I have learned about PTT & PT from my nursing school.

[CritterLover, BSN, RN]

Ok, you are going to get different "norms" because different labs use different machines and reagents, and have different normal ranges. (this, by the way, is true for most every test. Very important to check the normal ranges for the lab that did the test [usually printed on the written report]).

You are correct in that pt/inr is used to monitor coumadin therapy, and ptt is used to monitor heparin therapy.

Goals for pt/inr and ptts vary according to why the patient is on the anticoagulant. For example, you want a higher ptt if a patient is receiving heparin for a dvt or pe than if it is for cardiac reasons.

Similarly, you want a higher pt/inr for mechanical heart valve patients that for someone who is receiving coumadin for a-fib.

These goals also vary from facility to facility, but are generally similar. What you posted seemed about right, but I would have to look it up.

Now, on to pt/inr. Inr stands for international normalized ratio. It was developed because coumadin really doesn't have a wide therapeutic range, and as i mentioned above, different labs have different normals. So if your pt sample was sent to lab x one week, where their normal is 12 sec, and to lab z the next week, where their normal is 14 sec, there might be an inappropriate adjustment in your therapy if the difference in reference ranges isn't noted. That "inappropriate adjustment" could have serious consequences. Inr is pt's pt divided by the labs normal. So if the pt's pt is 14, and the lab's normal is 14, then the inr is 1. If the pt's pt is 28 and the lab's normal is 14, then the inr is 2. (please note the subtle difference between "normal" and "normal range." if the lab's normal pt is 14, normal range might be 12-16).

Does this help? Do I need to clarify anything?

[moliuchick, RN]

I am still confused about the inr. If the inr is >3, does it mean that there is a need to redo the pt test on the patient?

Wait, let me back up a step. what does it mean if a patient inr is between 1-3? is it a good sign? If a patient inr is >3, what does that mean?

[dianah, ASN]

The greater the INR, the longer it takes the blood to clot. An INR of 1 means the blood clots "normally" for that pt. If the pt is taking Coumadin (warfarin) to anticoagulate for a mechanical heart valve, the therapeutic INR should be around 3. An INR of three means the blood takes about three times as long to clot compared with the normal value for that pt. In our cath lab, we usually don't cath a pt if the INR is greater than 1.5-1.7, as the risk of hemorrhage from the punctured artery is increased (let's not increase risk to the patient from doing the exam!).

If the pt is taking Coumadin and the INR comes back 4, the dosage of Coumadin is usually decreased a little, and the test repeated, say, in a week to a month, depending on how well the anticoagulation clinic knows this particular pt and his/her patterns of response to Coumadin.

It takes about 5 days off the Coumadin in order for the INR to return to 1.

Now, some liver conditions create a coagulopathy that can cause the coags (PT, PTT, INR) to elevate. In that case, treat the underlying condition, if possible, while also treating the symptoms (if possible).

Short answers, hope they help. Good luck.

[moliuchick, RN]

dianah said:

The greater the INR, the longer it takes the blood to clot. An INR of 1 means the blood clots "normally" for that pt. If the pt is taking Coumadin (warfarin) to anticoagulate for a mechanical heart valve, the therapeutic INR should be around 3. An INR of three means the blood takes about three times as long to clot compared with the normal value for that pt. In our cath lab, we usually don't cath a pt if the INR is greater than 1.5-1.7, as the risk of hemorrhage from the punctured artery is increased (let's not increase risk to the patient from doing the exam!).

If the pt is taking Coumadin and the INR comes back 4, the dosage of Coumadin is usually decreased a little, and the test repeated, say, in a week to a month, depending on how well the anticoagulation clinic knows this particular pt and his/her patterns of response to Coumadin.

It takes about 5 days off the Coumadin in order for the INR to return to 1.

Now, some liver conditions create a coagulopathy that can cause the coags (PT, PTT, INR) to elevate. In that case, treat the underlying condition, if possible, while also treating the symptoms (if possible).

Short answers, hope they help. Good luck.

Now I got it. Thanx!

[CardioTrans, BSN, RN]

You have been given excellent information. There will always be different values "wanted" by each MD, and depending on the disease.

One thing that may have or have not been covered in your book, about the medication itself. Instruct the pt to always take the same kind of medication.

IE; if they have always taken warfarin (which is considered the generic), instruct them to make sure they always get warfarin from the pharmacy. If they have always taken Coumadin (the brand name), make sure they always get Coumadin. Even though we have all come to know that "generics are the same medicine just cheaper", it may not always be the case with these 2. The chemical makeup is slightly different. The same goes for Lanoxin and digoxin, digitek.

And don't forget to instruct them on foods to avoid with high Vit K content. Since Vit K is the antidote for coumdain/warfarin overdose.

Good luck on your boards!! Just remember, text book answers, and not real world answers.

[mepuck]

Interestingly, No one has answered the question about what the Ptt and Pt therapeutic ranges should be. I, too, am taking the NCLEX soon, and have found that many of the practice questions give a Ptt or Pt level without any clarifying information to evaluate whether or not the value is within a normal range. So frustrating to not have a basic normal therapeutic range for comparison.