How often should I get my INR checked when taking this medication?

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ajc1991

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Hello, I was diagnosed with Latent Tuberculosis (which means I am not contagious but the bacteria is still in my body and can cause Tuberculosis if I come in contact with someone who has Tuberculosis) and I am starting a treatment plan using the medication Isoniazid. Isoniazid is known to interfere with Coumadin, causing an increase in INR.

I go to the Coumadin clinic to get my blood tested. I was wondering how often I should go to the Coumadin clinic to get my blood tested after I start the medication. I was thinking of starting it today (Monday) and going to the Coumadin clinic on Thursday. I plan on getting my blood tested every 3 days. Would this be fine, or should I see them sooner?

Thank you,
Alex
 

dick0236

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In the past, when I have taken a new drug that may influence INR I might test a couple times per week for a week or so to check for interaction. You should not have to do the added testing for more than a week or two before you see a trend indicating a possible interaction. Testing more than every 3 or 4 days between tests will probably be a waste of your time and money. That's another reason to consider self-testing.
 

tom in MO

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Hello, I was diagnosed with Latent Tuberculosis (which means I am not contagious but the bacteria is still in my body and can cause Tuberculosis if I come in contact with someone who has Tuberculosis) and I am starting a treatment plan using the medication Isoniazid. Isoniazid is known to interfere with Coumadin, causing an increase in INR.

I go to the Coumadin clinic to get my blood tested. I was wondering how often I should go to the Coumadin clinic to get my blood tested after I start the medication. I was thinking of starting it today (Monday) and going to the Coumadin clinic on Thursday. I plan on getting my blood tested every 3 days. Would this be fine, or should I see them sooner?

Thank you,
Alex
Talk to your cardiologist. Mine wants me to call any time I get prescribed a new drug. They will tell you how often to test when you switch to a new medication that interacts with coumadin. For example, with strong antibiotics they want me to test on Day 5 and then 7 days later.
 

ajc1991

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Thank you both. I called the Coumadin clinic and they talked to my cardiologist and they both said to test in a week to see if it’s going to affect my INR.

Again, thank you both.
 

Protimenow

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I usually test every week. If my INR is lowered for surgery or another procedure, I give warfarin three days before testing - this usually brings it back into range.

I took amiodarone for a few days in March and April - the only thing it did for me was turn my intestinal contents into concrete. I don't know if it did anything to my INR.

Once you know what the medication will do to your INR, you can adjust your dose to compensate. This may require more frequent tests, but once it's under control, testing weekly will probably be fine.
 

SumoRunner

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I've been in the game a long time, so I went every 3-4 weeks, unless it's out of range wherein I'd go back in 2 weeks. Coumadin, which I was on for 28 years, has been discontinued, so a change to another brand of blood thinner has led me to a 3 week cycle.
 

pellicle

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I go to the Coumadin clinic to get my blood tested. I was wondering how often I should go to the Coumadin clinic to get my blood tested after I start the medication. I was thinking of starting it today (Monday) and going to the Coumadin clinic on Thursday. I plan on getting my blood tested every 3 days. Would this be fine, or should I see them sooner?
well, to me, no point in higher frequency than that. Be cautious about adjusting doses, wait till you see a clear trend. Then adjust in a minor way ... over correction is an issue

Lastly don't worry if you go a little out of range on the high side, and dipping lower than 2 for a few days is of relatively low risk.

Also, if you can avoid it, don't let monkeys manage you ...

Best Wishes
 

Protimenow

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Only one monkey manages MY INR, and this monkey is living in my skin. I'm stuck going to a 'coumadin clinic' to appease my new doctor, (and so I can compare the results on their CoaguChek XS to the results on mine). My INR will be in range, so the monkeys probably won't recommend any changes. I'll be interested in how often they want to see me.

SumoRunner - I'm glad that the interval you use works for you. I am more comfortable with weekly testing - sometimes extending to 10 days or so. One of the reasons is that, although a precipitous drop isn't likely, if your INR drops below 2, according to an old study by the Duke Clinic, you can form a clot in as little as ten day. I don't plan to take any chances (although, if stable, there's probably little practical risk of such drops).
 

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