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TPMT Testing before starting Imuran / Azathioprine

Was your TPMT tested prior to starting AZA?

  • Yes I was tested

    Votes: 40 71.4%
  • No I was not tested

    Votes: 13 23.2%
  • Beats me

    Votes: 3 5.4%

  • Total voters
    56

David

Co-Founder
Location
Naples, Florida
I'm curious how many of you had your TPMT tested before starting Imuran? TPMT is the enzyme that allows the body to process thiopurines of which Imuran is one.

Thiopurines [azathioprine (AZA), 6-mercaptopurine (6-MP) and thioguanine (6-TG)] have a well-established role as immunosuppressive agents in a variety of chronic inflammatory conditions, haematological neoplasia and in transplant rejection. Despite good overall clinical response rates, particularly when used as steroid sparing agents, adverse effects are a limiting problem leading to withdrawal in up to a quarter of patients. Severe myelosuppression is the most serious toxicity occurring early or occasionally later during treatment. An understanding of the competing pathways involved in the metabolism of thiopurines has important implications for predicting some of the more severe toxicity seen with these drugs.

Thiopurine methyl transferase (TPMT) is an enzyme catalysing the methylation of 6-MP, competing with xanthine oxidase (XO) and hypoxanthine guanine phosphoribosyl transferase (HGPRT) to determine the amount of 6-MP metabolised to cytotoxic thioguanine nucleotides. Allelic polymorphisms in the TPMT gene predict the activity of the enzyme such that 1 in 10 of the population are heterozygous and have approximately 50% of normal activity, whilst 1 in 300 are completely deficient. As a result, these individuals are at high risk of severe myelosuppression. Conversely, individuals with very high levels of TPMT activity are hyper-methylators in whom clinical response is less likely. Prior knowledge of TPMT status avoids exposure of individuals with zero TPMT to potentially fatal treatment with AZA or 6-MP and provides one of the best examples of predictive pharmacogenetics in therapeutics. This article reviews literature on the role of TPMT measurement prior to treatment with thiopurines and provides some guidance to the use of TPMT as a guide to tailoring thiopurine therapy.
Source
 

DustyKat

Super Moderator
When Sarah started Imuran 5 years ago the test wasn't available here.

When Matt was prescribed Imuran in December they drew the blood and started him on 50mgs whilst awaiting the results, it took about 3 weeks. Once the results were in and he was positive for the enzyme they upped him to his ideal dose of 100mgs.

I'm not sure but I think one of the reasons the GI prescribed it straight up at the lower dose was because Sarah has had no trouble tolerating it.

Dusty. :)
 
I dont think I was ever tested for that, but I have taken imuran for about a year once before, so I should be alright I hope.
 
I was not tested. Insurance was not paying for it in '06. It is rather expensive to pay for it alone. Instead the doctor and I decided to do regular blood tests, tapering back from once every two weeks, to monthly, to every two months. That was when I developed pancytopenia. That was the closest to death I ever want to be. My platelets dropped from an expected average count of 250,000 to 10,000. At the time my platelet count was so low, I was jaundiced, with blue lips! I have pictures to prove it... It took three weeks, and three transfusions for me to get back to "normal".
 
How much does the test cost?

Dusty. :)
IIRC, it was over 1,000$, maybe around 1100. This was in '06, so I am sure it is more expensive now.

My blood test for celiac's was almost 700$ before insurance. After the insurance carriers "discount" I ended up paying ~70$. Healthcare is a luxury in the US.
 
Yes, and it was ok, but when it came to it I couldn't tolerate it and ended up with Pancreatitis even on a low starting dose.
 
I have no idea. I had every test under the sun when I was first diagnosed. I was just out of the hospital where I almost died and every doctor I saw was poking me, or hurting me one way or the other. After a while I stopped asking why they were poking me and I just waited for the torture to end. Maybe I had it maybe not, still I was on AZA for a year and I ended up with a major flare and more poking and hurting.
 
My doctor told me it was critical to have the test done before starting Imuran. I also had it sent to Prometheus in CA and I paid $280 (US) for it because it was not covered by insurance. That was about 5 yrs ago. I am not sure why there is so much variation in the price?
 
I didn't and I'm sorry. My doc never even mentioned it. Now I'm just hoping my liver will recover. *facepalm* Why didn't the doctor mention itchy skin as a side-effect telling you your liver is compromised???????? I'm so upset with myself. I'm usually so good about looking up side-effects. I just figured itchy skin was, well, dry itchy skin. However, when you start leaving welts on yourself.... Oh, sheesh. I should have known. Please, please, please, get this test done before you take the drug.
 
I didn't and I'm sorry. My doc never even mentioned it. Now I'm just hoping my liver will recover. *facepalm* Why didn't the doctor mention itchy skin as a side-effect telling you your liver is compromised???????? I'm so upset with myself. I'm usually so good about looking up side-effects. I just figured itchy skin was, well, dry itchy skin. However, when you start leaving welts on yourself.... Oh, sheesh. I should have known. Please, please, please, get this test done before you take the drug.
If whenever you are being put on another drug, I would suggest some homework first.

Usually, you can google whatever meds your Doc is pushing, and a few minutes of homework can really make a difference in your decision to, or not to use said medication.

I have a nurses drug handbook that tells me everything there is to know about whatever medication I am being prescribed. From it's effects, to the side effects on the entire body, not just your tummy, or bottom...

We all have to remember that doctors are "practicing" their medicine on us. WE have to be vigilant in protecting our own best interests to avoid being hurt, even if it is inadvertent injury ( I would always hope a Dr would not deliberately hurt us.)

Take care!!:ghug:
 
Prometheus tests ran a little over $400. Medicare covers it. I did have to sign saying I agreed to pay if they refused to cover it.

If your insurance company turns you down, it can be appealed. Fight back. I don't want to hijack the thread, but for anyone in the US having trouble getting claims paid, I will be happy to tell you how to go about it.
 
My insurance covers it, which is what baffled me when my doc never suggested it. Just be sure to ask for it first. Just sayin.
 
I went on it three weeks ago without testing, but had been on it previously (not had any meds for about 3 years) but have stopped with possible pancreatitis . Next GI appointment is 7th December with no chance to see him sooner as hes on leave. But the nurse specialist was great and very supportive.
 
I was tested (for 6-MP). My doctor has been pretty serious about monitoring my bloodwork and ordering all sorts of fancy tests to test the drug levels in my system periodically -- I'm definitely glad I'm still covered by my dad's health insurance.
 
I had the test and my GI said my genetic make up wasn't good for me to go on imuran. He had actually called in the prescription to my pharmacy and by the time I got there, he had left 3 voice mail messages on my cell/home/work and called the pharmacy also. When I got there, there were sticky notes all over with my name on it like a red alert for me not to take this drug. Now, 6 months later because remicade isn't working on its own he has prescribed me imuran and I am concerned. How can something that was dangerous to me 6 months ago now be prescribed to me?
 
Hi,

Sorry to hear things have not worked out well for you.

I'd call the Doctor and remind them of what was said six months ago. Then ask them to justify the current decision. If you are not comfortable with the response, then discuss what other treatment alternatives are available to you.

Good luck.

Mark
 
I started Imuran last week. My doctor started me on 75mg a day based on weight and I had the blood drawn for the genetic testing the same day and am still waiting for the results. She told me that my insurance may not cover it even though it is now considered "standard of care" to have the testing done.
 

David

Co-Founder
Location
Naples, Florida
I had the test and my GI said my genetic make up wasn't good for me to go on imuran. He had actually called in the prescription to my pharmacy and by the time I got there, he had left 3 voice mail messages on my cell/home/work and called the pharmacy also. When I got there, there were sticky notes all over with my name on it like a red alert for me not to take this drug. Now, 6 months later because remicade isn't working on its own he has prescribed me imuran and I am concerned. How can something that was dangerous to me 6 months ago now be prescribed to me?
That IS concerning. As Mark said, I wouldn't take it until you consult with him.

What dose did he prescribe?

There is a small subset of the population that CANNOT take thiopurine medication (what Imuran is). There is another subset of the population that needs a reduced dose.
 
That IS concerning. As Mark said, I wouldn't take it until you consult with him.

What dose did he prescribe?

There is a small subset of the population that CANNOT take thiopurine medication (what Imuran is). There is another subset of the population that needs a reduced dose.
50 mg to start. My weight is 120.
 

David

Co-Founder
Location
Naples, Florida
While that's a low dose, with the big hoopla they made last time, I'm worried that you're in the group that should not take it at all. Definitely get ahold of him first.
 
My doctor was well ahead of me on this one. He was obviously using his experience and anticipating the course my condition was taking, and suggested checking my TPMT levels "just in case" Aza was going to be needed.
I was not keen to step up my meds, but it turns out he was totally on the ball. My flare kicked off big style, I ended up on steroids and by the time I had had enough and realised I desperately had to get on top of things, the TPMT results were ready (they took 28 days) and I could start the Aza straight away.

If he'd not been so proactive, I'd have had to wait another month for the results, and so have been on the steroids longer while waiting for the Aza to take effect. He saved me a lot of time and grief.
 
Yes, I was tested. It was ran along the other battery of tests like the PPD/Lung x-ray to test for TB and hepatitis tests.

Salofalk failed, Mezavant failed, I'm starting Imuran this week and I can't wait.
 
Yes, I was tested. It was ran along the other battery of tests like the PPD/Lung x-ray to test for TB and hepatitis tests.

Salofalk failed, Mezavant failed, I'm starting Imuran this week and I can't wait.
Hey, I was on salofalk & mezavant too, then methotrexate (failed too), then on to remicade, had the 3 loads, then at 5 weeks after 3rd dose, flared again, so now on remicade with the Imuran. You're following in my footsteps.
 
I'm really confused. I was just prescribed Azathioprine. The PA said i was one of less than 2% of the population per the tpmt test, and that I metabolize the medication. Does this mean I am homozygous or heterozygous? (If that's misspelled, sorry about that.) I will have blood tests every 2 weeks. Does it sound like this is safe? I know I will need to clarify this with the provider, but in the meantime does this make sense? The more I read online the more confused I get.
 

DustyKat

Super Moderator
Hi maja,

Do you mean that you don’t metabolise the medication?

If you don’t then I don’t think it matters whether you are homozygous or heterozygous, only that you don’t have the one of the pathways needed to metabolise the drug. That pathway being the enzyme thiopurine methyltransferase (TPMT).

Presence of the enzyme tends to lessen the risk of the developing the more serious side effects of the thiopurne drugs, that does not mean that people with the enzyme won’t get them though. For those without the enzyme a decision to use it by the GI would not be taken lightly and strict monitoring would need to be in place. Some doctors may use Allopurinol in combination with Imuran/6MP as a way of reducing the amount of thiopurne needed to be therapeutic.

Doctors differ in their monitoring regimens but this is the one I prefer, if you don’t have the enzyme you would need a stricter regimen than this over the long term:

Table 0901.jpg

I think it best that you discuss with your GI exactly what the results of the test were.

Dusty. xxx
 
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