Elevated GGT and Insulin on Steglatro / TG normal / ACTH equivocal


Sheri and Peaches
 

Peaches is a 2011 APHA mare with IR, but no history of laminitis.  On Steglatro since July 22, 2021 for the IR, along with hay soaked / tested / supplements to balance / dry lot / exercise.  She has finally been able to lose weight while on Steglatro, from 1,272 lbs to 1,115 lbs.

As of July 18, 2022, Peaches' Triglycerides were back to normal at 49 mg/dL (ref 14-65), while consistently getting one tablespoon L-Carnitine per day.  (Her TG had risen in April when I ran out of the supplement.)  However, Peaches' July 18, 2022 insulin was a disappointing 90 uU/mL (ref 0 - 42), which is as high as pre-Steglatro insulin.  Insulin results since starting Steglatro were 36 - 40 - 60 - 68 - 47 and now 90 uU/mL (ref 0 - 42).

In addition, Peaches' GGT has risen to 68 IU/L (ref 2 - 36).  This is her highest GGT ever.  Previous GGT results since starting Steglatro were 26 - 14 - 32 - 49 - 29 and now 68 IU/L.  In 2021, Dr. Frank at Tufts advised that Steglatro should be discontinued if GGT exceeds 75 IU/L.  My vet drew blood on July 25 for re-test, and I am waiting for those results.  In the meantime, I have stopped giving Peaches Steglatro because of the GGT approaching 75 IU/L.

On July 18, Peaches' non-fasting ACTH was an equivocal 24 pg/mL (ref <15 pg/mL normal in July and November; 15-50 pg/mL is Equivocal).  Previous ACHT tests have all been okay (October 2019, 2020 and 2021; June 2021 was one point into Equivocal).  My vet feels that her ACTH is fine and she is not PPID.  I'm wondering why her insulin has risen and am worried about having taken her off of Steglatro.  Is this a situation where a small dose of Pergolide may be warranted?   

Thank you for your insight and guidance.

--
Sheri P in IL 2021
Peaches Case History & files:  https://ecir.groups.io/g/CaseHistory/files/Sheri%20and%20Peaches


Eleanor Kellon, VMD
 

That 75 IU/L cutoff for GGT is purely arbitrary and not supported by any research but my goal with horses on SGLT2 inhibitors is normal liver enzymes. I agree that in this situation starting pergolide may be warranted since it doesn't seem like anything has changed except time of year. Maybe you could talk to your vet about starting pergolide at least for the seasonal rise period and then stopping end December, testing with TRH stimulation in early Spring. It is also possible your hay supply is not consistent. Send a retest of sugar and starch on the hay she is currently eating.
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Eleanor in PA

www.drkellon.com 
EC Owner 2001


Sheri and Peaches
 

Further to the above discussion in July, retest of Peaches' hay came back pretty consistent.  The earlier test in November 2021 showed 5.2% ESC + 1.0% starch.  Retest in August 2022 of the remaining supply of the same hay showed 4.7% ESC + 0.7% starch.  As of September 2022, Peaches has been switched to new supply of 2022 hay which tested at 7.2% ESC + 0.5% starch.


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Sheri P in IL 2021
Peaches Case History & files:  https://ecir.groups.io/g/CaseHistory/files/Sheri%20and%20Peaches
Blood results summary:  https://ecir.groups.io/g/CaseHistory/files/Sheri%20and%20Peaches/Peaches%20-%20Triglycerides%20Study
Peaches photos:  https://ecir.groups.io/g/CaseHistory/photosearch?p=title%2C%2C%2C20%2C1%2C0%2C0&q=sheri+and+peaches