The 12th Invest in ME Conference, Part 1
OverTheHills presents the first article in a series of three about the recent 12th Invest In ME international Conference (IIMEC12) in London.
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Abnormal Day 1 CPET, should I investigate metabolic myopathies or...?

Discussion in 'Autonomic, Cardiovascular, and Respiratory' started by ryan31337, Feb 9, 2017.

  1. ryan31337

    ryan31337 Senior Member

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    South East, England
    Hi all,

    Back in the summer I had a couple of CPETs, separated by a few weeks. On both occasions I had early AT and significantly low VO2Max. My VO2max was under 50% of predicted. More details in this thread: http://forums.phoenixrising.me/index.php?threads/vo2max-exercise-test.18431/

    From what I understand this isn't necessarily indicative of ME/CFS, in which day 1 test is usually normal(ish) and only a repeat test on day 2 is impacted?

    I was lucky to have a senior physiologist run one of the tests and his summary, in brief, was that there was cardiovascular limitation with functional impairment due to metabolic disease. We talked a little after the test and he was keen to know if I had had muscle biopsies taken or any similar investigations (I had not).

    So my question would be: would you think it valuable to send myself off to metabolic disease/myopathy consultant, if I can find one in the UK?

    Thanks,
    Ryan
     
  2. Valentijn

    Valentijn Senior Member

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    A one-day CPET would only be close to normal in mild patients. For those patients, a 2-day CPET could be useful in showing the impairment which doesn't show up on day 1. But for moderate and severe patients, the 1-day results are bad enough to show there is a pathology present, rather than deconditioning.

    I think it would be extremely valuable. Mitochondrial myopathies can certainly cause the symptoms seen in ME patients. It's not clear if the exercise intolerance is identical to PEM, as it's a patient group which I think has not been compared to ME patients after exertion.

    I'm currently trying to get assessed for MELAS, as I've got a couple symptoms of it (diabetes and hemiplegic episodes) in addition to my "usual" ME stuff.
     
    ryan31337 likes this.
  3. ryan31337

    ryan31337 Senior Member

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    South East, England
    Just to add a little more context, I decided to play the foolish game of reading some literature on metabolic myopathies in isolation and leap to some conclusions, so take with a pinch of salt :rolleyes:

    This flow diagram interested me:
    nihms195802f1.jpg
    from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2872126/

    - I have a very significant negative reaction to normal/high carbohydrate diet - considered reactive hypoglycemia by endocrinologist but not confirmed by testing, and seemingly much more significant than most doctors expect for typical RH.

    - I don't know much about Hemolytic anemia and how it presents, but I did notice elevated bilirubin occurs as a result and this is something I have always had (explained away as Gilbert's)

    ---

    Thanks @Valentijn, I was hoping you might reply as I had been following your thread on MELAS. I've yet to dive into genetics but know its something you're very clued up on, so could you tell me if there is this 23andme data has any relevance to myoadenylate deaminase deficiency?
    AMPD1 rs17602729 AG

    I'm afraid I don't know how to interpret it but had seen a publication suggesting heterozygous mutation sometimes had an impact, especially when coupled with other myopathy.

    Thanks.
     
  4. Valentijn

    Valentijn Senior Member

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    You'll note that the top and bottom paths both involve myoglobinuria. Basically that would involve peeing a rather disturbing red or brown color, and it makes diagnosis a lot easier for those conditions. Without that symptom, it's only the center path which remains, leading to mitochondrial disease.

    It looks like mutations on that gene are only pathological if there's basically no enzyme activity at all as a result. And that only happens when homozygous or compound heterozygous. Even some homozygotes aren't affected, due to the gene occasionally skipping the exon with the nonsense mutation, therefore continuing on to create most of the rest of the enzyme.

    Often heterozygotes can have a mild version of a disease, but probably not in this case, since any level of activity is enough. It is possible that you have another heterozygous mutation on the gene which isn't tested by 23andMe, but that's probably pretty unlikely.
     
    Hutan likes this.

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