ACTH still high


Mikaela Tapuska
 

The vet called this morning with Zahr's ACTH (and CBC) results from July 27. Unfortunately his ACTH is up from when we tested it in May, and came back at 31 pmol/L. At the time of testing he was on 3mg compounded pergolide and 0.5 tab of prascend, which we were treating as an equivalent to the 3mg prascend he had been on since the beginning of June. I should have his actual blood work results back from the clinic shortly, so I can get those numbers and documents added as quickly as I can to his case history.

We started titrating his meds up again on the 29th, he is now at 4mg as of Sunday and with his correct Rx this time - 4mg CP + 1 tab prascend. Clinically he seems to be doing well and is still quite comfortable after his trim last weekend. I know the rise had already started when we tested him in July, but if it was that high then I know it will continue to push up higher as we reach the peak of it.

I wonder if I should keep him at the 4mg for now, monitor clinical signs, and then retest at the end of September as planned when he in theory should have reached the peak of the rise, or if I should bump him up another 0.5mg now while it still might be able to make a difference in his ACTH levels. Either way, if I retest in 3 weeks or at the end of September I think we will already be into high point where further adjustment of meds won't have a significant effect. Any thoughts on this?

On a positive note, his overall white blood cell count has started to come back up again after continually trending down since November 2021. Technically his numbers are still low but at least improved from last time! He was off all NSAIDs for the two and a half months prior to bloodwork, so hopefully that was the culprit and his WBCs continue to normalize as he progresses.

Thank you!
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Mikaela Tapuska in Calgary AB, 2021

Case History: https://ecir.groups.io/g/CaseHistory/files/Mikaela%20and%20Zahr

Photo Album : https://ecir.groups.io/g/CaseHistory/album?id=274255


Sherry Morse
 

You're chasing the rise at this point and a .5mg bump up will probably not do that much so if you are going to add more meds in you need to be thinking in terms of 1mg or more.  Did they provide you with an adjusted range for during the rise or just the standard 2 - 10pmol/L range?

Were this my horse since we are still a month out from the peak of the rise I'd probably err on the side of caution and bump him up another mg now and monitor with a plan of testing him after the rise to see if the dose is keeping him well controlled or not.  If his level is in the reference range at that point you can consider decreasing to a lower level but testing prior to the rise starting again to confirm that dose is correct for him or not.




We started titrating his meds up again on the 29th, he is now at 4mg as of Sunday and with his correct Rx this time - 4mg CP + 1 tab prascend. Clinically he seems to be doing well and is still quite comfortable after his trim last weekend. I know the rise had already started when we tested him in July, but if it was that high then I know it will continue to push up higher as we reach the peak of it.

I wonder if I should keep him at the 4mg for now, monitor clinical signs, and then retest at the end of September as planned when he in theory should have reached the peak of the rise, or if I should bump him up another 0.5mg now while it still might be able to make a difference in his ACTH levels. Either way, if I retest in 3 weeks or at the end of September I think we will already be into high point where further adjustment of meds won't have a significant effect. Any thoughts on this?

On a positive note, his overall white blood cell count has started to come back up again after continually trending down since November 2021. Technically his numbers are still low but at least improved from last time! He was off all NSAIDs for the two and a half months prior to bloodwork, so hopefully that was the culprit and his WBCs continue to normalize as he progresses.


Mikaela Tapuska
 

Hi Sherry,

As far as I know just the standard 2 - 10 pmol/L range. I've not seen the files yet, but when we have tested over the fall in the past that is the range Idexx has provided. Although, the vet mentioned that fall numbers for normal non-PPID horses can go up into the 30s (pmol/L) but of course that is not ideal for one with PPID.

That sounds like a good plan. He has continued to eat well throughout the last two increases (fingers crossed that keeps up) so I am hopeful that would continue if we do the 0.25mg titration up every 4 days again. I'll plan to increase meds again this Thursday and work up from there.

Thank you!
 
--
Mikaela Tapuska in Calgary AB, 2021

Case History: https://ecir.groups.io/g/CaseHistory/files/Mikaela%20and%20Zahr

Photo Album : https://ecir.groups.io/g/CaseHistory/album?id=274255


Mikaela Tapuska
 

I received the document from the vet’s today so have his lab results uploaded under his file (and will update his dosage information etc. in his CH asap as well, apologies for it not being done yet - it has been a crazy week). All it said regarding the 2 – 10 pmol/L range was “The equine endogenous ACTH reference interval reflects values obtained in mid to late summer, prior to the expected seasonal (Fall) increase seen in this species.”

 

Today Zahr was walking slower than he has been recently, which is usually how things will start before he goes full on footsore. We are increasing his meds again tomorrow, but every time it feels like we make progress and his symptoms improve, after a very short period they come back…

 

In the group’s experience, would it be overdoing it to continue titrating him up all the way to 8mg CP (~6mg pergolide)? I’ve been recently reading another thread that sounds like it may be a similar case to Zahr’s in terms of dosage and ACTH struggles, and tripling the dose was suggested - https://ecir.groups.io/g/main/topic/92800912#281310

I have a 90-day supply of 4mg CP capsules that we just started using, so I can easily titrate up with prascend and get him to the point where he is on 2 caps daily instead of one + multiple prascend tabs which at least is much more reasonable cost-wise. I just want to stop this before he has yet another flare up.

 

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Mikaela Tapuska in Calgary AB, 2021

Case History: https://ecir.groups.io/g/CaseHistory/files/Mikaela%20and%20Zahr

Photo Album : https://ecir.groups.io/g/CaseHistory/album?id=274255


Sherry Morse
 

Hi Mikaela,

That's a good plan if you have the meds on hand to do it.  I would titrate him up as quickly as you feel comfortable with.




Mikaela Tapuska
 

Thank you Sherry, I am aiming to increase by 0.25mg every two days. Fingers crossed that he responds well.

Would it perhaps be worthwhile to try Metformin with Zahr if he continues to present with symptoms of high ACTH, to at least keep insulin in check through the seasonal rise? Maybe that is putting the cart before the horse as we haven't even reached his 6mg pergolide (8mg CP) yet. I know the PPID is the underlying issue and Metformin won't address that, but I am thinking it may be something to keep in my back pocket in case we can't get his ACTH down adequately at this point.
 
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Mikaela Tapuska in Calgary AB, 2021

Case History: https://ecir.groups.io/g/CaseHistory/files/Mikaela%20and%20Zahr

Photo Album : https://ecir.groups.io/g/CaseHistory/album?id=274255


Sherry Morse
 

Hi Mikaela,

Unless you tested his insulin and it was high enough to be in the danger zone I would keep Metformin as a 'in case of emergency' item.




Mikaela Tapuska
 

Okay, that sounds like a good plan. I suppose the first step will still be to see where his ACTH actually is in September, and then we can go from there and do other tests as needed. Thanks again Sherry!

--
Mikaela Tapuska in Calgary AB, 2021

Case History: https://ecir.groups.io/g/CaseHistory/files/Mikaela%20and%20Zahr

Photo Album : https://ecir.groups.io/g/CaseHistory/album?id=274255