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Low platelets and Azathioprine - my test results

I've had a low platelets issue for several years now but since I am asymptomatic ie. not bleeding profusely if I cut myself, it was decided to "park" the issue. In September 2013 I felt that we really should investigate it further so we could decide if Azathioprine would still a viable drug for treating my Crohn's and to make sure there wasn't a more serious underlying problem. My gastro consultant supported this and the investigation started.

Two bone marrow biopsies later and we have the answer. The low platelets are not indicative of a bone marrow abnormality but are drug induced with the likely cause being to 8+ years of Azathioprine. It is a known side effect of this drug. Azathioprine is sometimes used to maintain Crohn's remission but if I get to the point where I need to go back on medication it will not be considered as an option.

The low platelets can return to their parking bay.

The above is just MY experience of taking that drug and as we all react differently to medications you should not assume you will end up in the same situation. Whilst I stopped taking it when we realised there was a potential problem it has not damaged my bone marrow sufficiently to need to take further action. The haematologist described it as like having a "four cylinder engine but only running on three". Would I have agreed to starting Azathioprine back in 1998 if I knew then what I know now? Yes. For nearly ten years it kept surgery at bay so that when the knife became inevitableI was in a much better position both financially and mentally to cope.

I've added a couple of posts on my blog detailing the tests and the conclusion. It's all here : http://goo.gl/f4hf5H


Super Moderator
hello there,

Sorry to hear that this medication did not work out for you. It is true that this can become a problem for some taking Imuran/Azathioprine/6-mp(mercaptopurine).

This is why it is important to get routine blood tests while on these medication. Even if you respond to the medication very well at first, over time your body changes and may choose to accept or reject the medication in a new way.

Your white blood cell count should be periodically monitored. You should also be periodically tested for liver toxicity via Prometheus TPMT blood testing:

TMPT test is an enzime blood test to help determine how well you will metabolize/process thiopurine. Imuran is a thiopurine medication and has it's own set of risks (as does all crohn's medication). I personally wouldn't even consider starting to take Imuran without this blood test having been done first.

The results of these tests should let you know the following about how you react to these types of medications:

6-TGN level / 6-MMP level = Clinical response (the likelihood of how your body will react to the medication)

Low/Low = Subtherapeutic dosing or non-compliance

Low/High = MP resistant

Normal/High = MP resistant or high risk for abnormal liver chemistries

Normal/Low = Responders or refractory

High/ Low = True refractory, responder or risk of leucopoenia

High/High = Over-dosed

* Low 6-TGN is defined as <235 pmol/8 ×108and high >450 pmol/8 ×108. High 6-MMP is defined as >5700 pmol/8 ×10