Can someone please explain INR & Coumadin therapy to me?

It was easier for me to remember Coumadin this way:

Certain conditions or inactivity can cause clotting. Clotting is bad. Clotting makes DVTs, PEs, MIs and strokes. So basically anyone at risk for clotting needs some kind of anticoagulation therapy--SCDs, Lovenox, Heparin, and/or Coumadin.

Heparin and Lovenox work fast, so patients will be given those while in the hospital. Simultaneously, the doc will start them on Coumadin. The reason is that Coumadin takes a few days worth of doses to begin to be effective.

You check the INR. Most people have a normal INR of around 1.0. It's really not necessary to remember exactly what the letters stand for--I think it's International Normalized Ratio, so that wherever you go in the world, the numbers will be the same, so that everyone is on the same page when the numbers come in.

When the Coumadin kicks in, the INR should go up. The desired INR will vary for the condition being treated. A person who is an A-fibber will usually go home once the INR reaches around 2.2, but a person who had a heart valve replacement needs to be a little higher.

That is why the Coumadin is given at around 1800. It then has a chance to peak in the system when labs are drawn for the morning. You check the daily Prothrombin/INR labs to make sure that the patient is becoming therapeutic.

Then you'd check in the Dr.'s Progress notes to see what the plan is, and what number he's shooting for, because quite a few of these patients literally are stuck in the hospital till their INR numbers are right.

I hope that helps a little, and I'm sure others will be happy to contribute to this thread, because Coumadin/anticoagulation therapy is a Biggie drug, and everyone really needs to know it inside and out.

Here's some good links:

Understanding Deep Vein Thrombosis
Has pictures of what leg looks like with DVT.

Warfarin Therapy: Evolving Strategies in

Anticoagulant Therapy

ENW: Research- International Normalized Ratio (INR) [Emergency ...


Anticoagulation therapy supplement.


Very Technical:
Guide to Anticoagulant Therapy: Heparin A Statement for Healthcare ...

40 hr CE Program, costs $$ : Anticoagulation Therapy Management Certificate Program

Wow, excellent reply Angie O'Plasty! That's a good explanation about heparin acting faster and Coumadin slower. Many pt's ask why they are on both. Also I believe each medication affects a different end of the coagulation cascade (remember that from phys class? ).

In some facilities you will see a protocol or sliding scale to determine the daily Coumadin/warfarin dose. When I worked in a subacute nsg home, we had a paper printout, much just an insulin sliding scale. For example, if daily INR was 1.0, then give 5 mg Coumadin... if INR is 2, hold Coumadin today, etc... Where I work now, we have a computerized protocol. The computer pulls the daily INR lab results and determines what amount we should give at 1800. Sometimes the protocol tells us to call the physician for the amount.

While people are in the hospital, they usually have daily INR's. If people are on coumadin for chronic health problems such as stroke or afib like Angie said, then they will most likely go into their family clinic to have their INR's checked every couple of weeks or monthly or so.

Usually while on Coumadin therapy, the INR should be between 2 and 3. Occasionally the range should be 2.5 to 3.5. Many things can affect the INR; antibiotics for one, and an increase or decrease in consumption of green, leafy vegetables. Patient's on Coumadin need very good education, stressing the importance of their periodic INR draws. Too high of an INR can lead to bleeding, etc..., and too low of an INR can results in clots; PE, etc...Also, many patient's are taken off of their Coumadin before procedures/surgeries due to the risk of bleeding and placed on Heparin or Lovenox, which have a much quicker clearance.

Here's a post I wrote in another thread:

PT/PTT are laboratory tests that measure the clotting time (how long it takes blood to clot.)

PT/PTT are blood tests and INR is a ratio calculated from the PT.

At least a dozen blood proteins, or blood clotting factors, are needed to clot blood and stop bleeding (coagulation).

Prothrombin, or factor II, is one of several clotting factors produced by the liver. Prothrombin time (PT) measures the presence and activity of five different blood clotting factors (factors I, II, V, VII, and X). This test measures the integrity of the extrinsic and common pathways of coagulation. The prothrombin time (PT) measures the clotting time from the activation of factor VII through the formation of the fibrin clot. Adequate amounts of vitamin K are needed to produce prothrombin. Warfarin (Coumadin) is sometimes prescribed as a "blood thinner" because it is an effective vitamin K antagonist (blocks the formation of vitamin K).

The activated partial thromboplastin time (PTT) measures the function of several other clotting factors, found in the intrinsic and common blood clotting pathways. It measures the clotting time from the activation of factor XII through the formation of the fibrin clot. PTT prolongations are caused by factor deficiencies (factors VIII, IX, XI, and/or XII), or inhibitors (most commonly, heparin). Heparin prevents clotting by blocking certain factors in the intrinsic pathway.

PTT and activated partial thromboplastin time (aPTT) are basically the same thing. The aPTT has largely replaced the older PTT, which was unable to incorporate variables in surface/contact time: http://www.rnceus.com/coag/coagptt.html

PT is used to monitor treatment with warfarin (Coumadin). Once warfarin is discontinued, it usually takes several days to clear it from the system. The PTT test allows the provider to check that there is enough heparin in the blood to prevent clotting, but not so much as to cause bleeding. Once heparin is discontinued, its blood-thinning effects usually only last a few hours.

The greater the PT/PTT values, the longer it takes the blood to clot. HIGH PT/PTT = risk for BLEEDING. LOW PT/PTT = risk for blood clots/ stroke.

The INR stands for International Normalized Ratio. The INR is calculated from the PT and is intended to allow valid comparisons of results regardless of the type of PT reagent used among different laboratories (INR = [patient PT / mean normal PT]). The INR is a method of standardizing the PT for coumadin anticoagulation. Before the INR, different labs using different reagents had different controls and widely differing PT value ranges.

An INR of 1 means the blood clots "normally" for that pt. The greater the INR, the longer it takes the blood to clot.

The warfarin (Coumadin) dosage for people being treated to prevent the formation of blood clots is usually adjusted so that the prothrombin time is about 1.5 to 2.5 times the normal value (or INR values 2 to 3). A patient may take warfarin to anticoagulate for atrial fibrillation (target INR around 2.5) or for a mechanical heart valve (target INR 3). An INR of 3 means the blood takes about three times as long to clot compared with the normal value for that pt.

Which value, PT or PTT, does heparin influence?

Which one does coumadin?

Stumped?
You can find the right answer by counting to 10:

- - - - - - - - - - = 10

H E P A R I N (7 letters) + 3 (PTT) = 10

C O U M A D I N (8 letters) + 2 (PT) = 10

Here's another one:

What is the antidote for heparin overdose?

Protamine sulfate (just remember P M S)

What is the antidote for too much Coumadin?

Vitamin K (just remember the hard "C" at the beginning of coumadin!)

thank you for this explanation

I once was told this and it really helps me remember INR
Ok so the if the normal persons blood takes 30 secs to clot a person on coumadin you want their inr to be 2 or 3 so you want their blood to take 60 to 90 secs to clot
so 90/30=3
if i prick your finger it would take 30 secs
i want my pt's pricked finger to take 60 to 90 secs to prevent complications
bingo inr

Hello,

This is Kitt and the info and the links posted here were fantastic. Many clinics now run a Coumadin Clinic or Anticoagulation Management Service and see their patients on a regular basis by a RN or NP. It is proving to be very beneficial to the patients in keeping thier levels in control.

Also there is a huge emphasis on patient education when the patient comes into the clinic to be seen and evaluate their lab results. This provides the patient with a one on one monitoring by a trained person that deals only with Anticoagulation management.

It is important to have regular INR (International Normalized Ratio) done to to ensure optimal therapy.

Respectfully,
Kitt