Re: High ACTH no symptoms

Kirsten Rasmussen

Hi Brenda,

I don't see your new results in Stormy's Case History, but looking at the previous testing I would say we generally don't recommend a TRH stim test in the seasonal rise because we have no knowledge of what the stim result should be for a diagnosis.  So not sure if the post-stim is actualky diagnostic, although it was awfully high.  His baseline was a smidge above normal but that was in August when the seasonal rise is underway so that on its own is not concerning.  Was Stormy the one with the mild symptoms and baseline ACTH of 176 more recently?  That higher baseline ACTH during seasonal rise is normally considered a positive for early PPID here.

I also learned here that PPID can flare up in some horses around the spring equinox, or March 21, which is interesting given that Stormy had elevated ACTH then (or did you transcribe the 107 glucose number there by accident?) plus a laminitis event on Mar 2.

As Martha said, ACTH does not tell the whole story.  There are other hormones that would be a better indicator of PPID that we should be testing for but do not/cannot at this time.
when you consider that of all the hormones put out by the pituitary in PPID, ACTH is by far at the lowest concentration. We're way past the time to switch to testing POMCs across the board or alpha-MSH instead.

I think I personally would not treat now (assuming they have no signs that have worsened in the autumn) and the seasonal rise is on the down swing.   But I would be closely watching ACTH and insulin in the spring and again next fall, as well as possible signs of PPID, and if you do another TRH stim test it should be between December and June.

Kirsten and Shaku (IR) - 2019
Kitimat, BC, Canada
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