Apologies for multiple posts but I did the TRH stimulation test for both of my horses, and I'm afraid things can get mixed up.
Atticus's TRH stimulation test was negative for PPID, but there was a blip of ACTH at 30 minutes. The vet said that according to the new Cornell protocol the 30 minute reading is optional and the elevation isn't significant, so he wasn't concerned, but I am.
His plasma ACTH was 17.6 pg/ml pre TRH administration, 90.2 pg/ml at 10 min, and 69.5 pg/ml at 30 min. His non-fasting insulin was within the range, 27.56 uIU/ml, but leptin was slightly elevated, 10.42 ng/ml.

Thank you very much for your help interpreting this!
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Ed P in TX 2022
Atticus's Case History
Atticus's album
Gunner's Case History
Gunner's album

I’m pretty sure I’ve read here that 10 minutes post stim is long enough.
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The TRH Stimulation test is more likely to give a false positive, and it is less likely to give a false negative.  However, the timing of the 10 min draw is critical, it must be at 10 minutes, not 9 and not 11.  Could timing have been a factor for Atticus?  If not, I would consider this a negative.

I think you had fall 2022 bloodwork, too, but I'm not seeing it in the Case History.  But I think it was Gunner who had the ACTH pushing 50 in the fall, not Atticus, which is consistent with what your TRH Stim tests are telling you.

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Kirsten and Shaku (EMS + PPID) and Snickers (EMS) - 2019
Kitimat, BC, Canada
ECIR Group Moderator
Shaku's Case History
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Snickers' Case History
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Thank you Sherry, Martha, and Kristen for responding!

I'm not letting my guard down. It is tempting to let one's wishful thinking to take over, but I think I now know better than that. The test results are the only objective feedback that I get from the changes in diet, supplements, and overall management that I've implemented. I'm trying to interpret these results and I'm skeptical of the vet's conclusion (negative for EMS, negative for PPID) - Atticus did founder, after all. In trying to make sense of this, what are the numbers that I should consider safe to maintain? Sherry, you are saying that non-fasting 27.5 insulin is IR. Cornell gives the 10 - 40 range as being normal or <20 for horses fasted overnight. These numbers are what I think the vet is going by. If this is too optimistic then how should I scale it?

For TRH stimulation, the vet was following the protocol. He was the one who set the timer, but Atticus was right there waiting so there should not have been any time discrepancy. His 10-minute reading is well within the range Cornell provided, but if their insulin range is off, is it also the case that the ACTH range is off also? My concern was the 30-minute reading that was elevated, but the vet was saying that a) it was only elevated slightly, and b) that the 30-minute reading was optional to begin with.

Kristen, I just updated Gunner's case history yesterday, so his is current, and I'm in the process of updating Atticus's. Time gets away from me and I don't document every change that happens, and then going back and reconstructing the dates is a challenge. I need to stay more current with the case histories so that there are no big gaps to fill. My fault entirely. I'll update Atticus's case history asap. 

With Gunner, I need to figure out the pergolide dosage and how to start. His September ACTH was 49.8 (pushing 50, as you said, Kristen), but it was only 16 in January pre-TRH administration. What I keep reading is that the pergolide dose needs to be the lowest that maintains normal ACTH, so if the baseline ACTH is normal already but the TRH Stim is positive, how do you figure the dose? I have a separate post asking this so I shouldn't really bring this up here, but you mentioned Gunner, and so he's another big question mark.

Atticus's ACTH in September was 35.7 and 17.6 in January pre-TRH administration.

Thank you again for all your responses!
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Ed P in TX 2022
Atticus's Case History
Atticus's album
Gunner's Case History
Gunner's album

Hi Ed, to expand on Sherry's response, I suggest reviewing this link:
https://www.ecirhorse.org/FastingInsulin-LabRefRanges.php
Particularly the section " Why Reference Ranges are not Normal".  The reference range includes horses that are not symptomatic for laminitis, as well as fasted, non-fasted, grain-fed, etc, horses.  As Sherry said, anything above about 12-13 uIU/ml is abnormal for a non-fasted horse on forage only.  Depending on the lab and the insulin assay they use, that cut-off can vary a bit, but it gives you an idea.  Atticus is an Andalusian, a breed highly prone to having EMS (all Spanish breeds are).  His insulin results confirm that.  He does not need to have PPID to explain his past founder.  Keeping his insulin in the 20s or lower would be ideal, but below 40 uIU/ml for sure.  Even at 40 you may see signs of sub-clinical laminitis, like stretched whiteline and sensitivity turning or on hard ground.  The same study that set the non-fasting EMS cutoff at 12-13 uIU/ml found that horses with insulin above ~80 can develop acute laminitis.

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Kirsten and Shaku (EMS + PPID) and Snickers (EMS) - 2019
Kitimat, BC, Canada
ECIR Group Moderator
Shaku's Case History
Shaku's Photo Album

Snickers' Case History
Snickers' Photo Album

Sherry and Kristen, thank you for responding! I studied the article last night and got a much, much better idea of what the ranges are and what the goal is. Very much appreciate the help and the link!
Kristen, thank you also for providing additional numbers. Yeah, he's an andalusian and Gunner is a half-arab. Both  are genetically predisposed. They have both been below 40 for a year now, and I thought it was okay, but I now have another goal of keeping them below 20 or even 15. Thank you both so much again!
Kristen, thank you for commenting in the Gunner's post also. I was typing a response when you posted, so our posts "crossed" so to speak, but I really appreciate your input there as well!!!
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Ed P in TX 2022
Atticus's Case History
Atticus's album
Gunner's Case History
Gunner's album