Different types of insulin (or glucose) tests, vet is asking which one I want done


Laura and Ero
 

I'm having a 6 month follow-up metabolic panel done on Ero (Vit E re-check as well). Now that's he's moved to a new place, we're starting over on everything (again). I was going to have just insulin and glucose re-tested (via Cornell), but my vet asked which test I wanted done. Fasting or non-fasting. I thought it was the non-fasted (hay only up to four hours before testing, no turnout/exercise), but in researching this again I'm getting confused. 

https://ecir.groups.io/g/main/topic/77817897#256829 
I was reviewing the above thread and am looking for guidance and clarity so I can try to work WITH my vet (it's a delicate discussion). Which tests should I be requesting and should I be so bold as to ask which colored tube top be used? 

I can use yet another vet, but vet relationships are important. The large practice in my area uses Antech (not Cornell) and I'd like to keep the labs consistent. Given Ero's many ups and downs since January, I'm also debating just running a full metabolic panel again so that I have more information to compare to. His initial results are from Cornell and are in my CS and also posted in our file.

Appreciate input, advice. Vet is coming 6/16 at 9am so I'm trying to get very clear on what I'd like to have tested.

Thank you,
Laura


--
Laura and Ero

October 2020 | Colgate, WI USA 

Ero Case History

Ero Photo Album


celestinefarm
 

Laura, I was going to post this on a separate thread. Michigan State has changed the assay they are using to test ACTH and have changed all of their testing protocols and reporting to what I believe is how Cornell is reporting. Hallelujah! They are offering to provide insulin numbers for a horse that has only had hay to consume for the past four hours, and they also are providing numbers for a horse that has been given grain, commercial feed, etc. They will categorize it according to fasting or "fed" . 
This testing change is a vast improvement over what we were getting just last year. I realize there may be concerns that Dr. Kellon or others will have with MSU's current offerings, but for those of us located close, it is good to have a lab more aligned with Cornell.
I would stay with what you have been doing so you have a more apples to apples comparison.I believe from MSU's statements, fasted will give a more definitive result. I just had blood pulled this am for Tipperary and my vet was there at 7 am as we have done for a few years. However, it is good to know that if a horse has blood pulled after eating feed, etc. they can still provide numbers and a diagnosis of IR possible IR , or normal . See the information from MSU at this link. 
Equine Endocrine Testing | College of Veterinary Medicine at MSU

Dawn Wagstaff and Tipperary   

Saline, MI  2003

Tipperary Case History

Juniper Case history: https://ecir.groups.io/g/CaseHistory/files/Dawn%20and%20Juniper/Case%20history%20Juniper.pdf .


Laura and Ero
 

Good to know and thank you for the link and update on MSU labs. Ero is EMS (I feel in a constant subclinical status) and I believe had a recent bout of laminitis at his prior barn (rads showed no rotation though). He's now turned out on a dry lot daily and is stalled at night. I doubt he's PPID and I know he has high leptin based on his eating patterns and prior test results. 

He's barely working due to a series of injuries and hoof sensitivity despite sole growth and much improved hoof care since Nov. (I'm having FormaHoof done on his hinds for sure, to address NPA and the need to grow heel, and so that he can be comfortable enough on his feet to start under-saddle work again - exercise. Working with an osteo on his SI issues as well ... it's all connected.)

A revised diet will need to be done as soon as I can get the new hay tested (just came in off the field last weekend). For now, he's STILL on an emergency diet just to be safe and so that I have a baseline. 

Therefore, having this updated bloodwork is necessary for an updated and and accurate baseline. I haven't come THIS far, not to keep going and trying to get it right (well as close as I can). 

In summary, if I'm understanding you ... I should go with the fasted test (for consistency). I was also advised to run the TRH Stim test as his latest event boggled everyone. I've never done that, but I'm tired of being in the dark on what's going ... and I'm trying to eat information by the shovel-full. 

--
Laura and Ero

October 2020 | Colgate, WI USA 

Ero Case History

Ero Photo Album


Nancy C
 

HI Laura and Dawn
I should go with the fasted test (for consistency). I was also advised to run the TRH Stim test as his latest event boggled everyone.
I may be missing something, but ECIR does not recommend a full fasted test, which is what MSU is reporting on (6-12 hours fast).If he was fasted for his first test, I missed that, but either way, you want to see how he responds to low ESC and Starch diet. So, no grain, low or soaked hay, test four hours after a break in any overnight fast. IOW if he typically runs out of hay overnight.

Info here that you may have seen already on fasted labs and lab reference ranges:  https://www.ecirhorse.org/FastingInsulin-LabRefRanges.php

The above goes into the evolution of testing recommendations, including fasting and oral glucose developed from human testing.

If you feed the horse as above, you will get a more accurate picture of his EMS status.

The thread you referenced is relative to which tube to use to get most accurate results and Dr Kellon is saying : Bottom Line: Use serum or heparin tubes for insulin testing. Varying sample type between tests will not give you accurate results.

https://ecir.groups.io/g/main/topic/77817897#256829

Do not use the EDT tubes (purple top) for insulin. Not sure how this plays into MSUs new testing but IMO the safe bet is to use the serum or heparin (red top) tubes. I would absolutely ask which tube they are using for insulin and maybe have the study at the ready if needed. 

If you need to do TRH, now is a good time.

Hang in there. Lots to learn but it gets easier.

--
Nancy C in NH
ECIR Moderator 2003
ECIR Group Inc. President/Treasurer  2020-2021
Join us at the 2021 NO Laminitis! Conference, August 13-15, ECIR Virtual Conference Room


Eleanor Kellon, VMD
 

Dawn,

Do you have another link that specifies "fasted" includes horses on hay only?
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001


Sherry Morse
 

Hi Laura,

We recommend non-fasting testing (last hard feed at least 4 hours prior to testing, hay in front of the horse until tested if possible).  You can read more about lab reference ranges and fasting tests here: https://www.ecirhorse.org/FastingInsulin-LabRefRanges.php.  Since the vet appointment is at 9am that would mean that somebody should make sure Ero has hay at 5am.

Your vet should be used to Cornell's protocols and what is needed to submit results as you've already had results from Cornell so it's up to you if you want to quiz them on the submission guidelines. 

As far as what tests to run - you don't need to run leptin (unless you want to) but getting insuin, glucose and possibly an ACTH level may be a good idea at this point in time.  Since Ero's last test did not indicate he was PPID if you want to check that the TRH test may be a better option than the straight ACTH test.



Eleanor Kellon, VMD
 

Unless you get test results that do not match up with the horse's  clinical presentation, it's always best to stay with the same lab because comparisons will be more accurate.  I would stay with Cornell. You can print out (or link in an e-mail) the sample handling directions and request for mailers. Insulin, glucose and ACTH.

--
Eleanor in PA

www.drkellon.com 
EC Owner 2001


celestinefarm
 

Dr. Kellon,
The fasted definition is in the description under PPID and Insulin Dysregulation.
Aside from the timing of sampling in reference to a grain meal, there are no restrictions to feeding of hay. Of the tests described in this section, the insulin assay is of the least sensitivity and specificity for diagnosis of PPID. Insulin resistance is also a component of the condition in horses currently referred to as Equine Metabolic Syndrome.
--
Dawn Wagstaff and Tipperary   

Saline, MI  2003

Tipperary Case History

Juniper Case history: https://ecir.groups.io/g/CaseHistory/files/Dawn%20and%20Juniper/Case%20history%20Juniper.pdf .


Eleanor Kellon, VMD
 

If it's true that free access to hay =  fasting, the test interpretation is still way off. So are the "fed" numbers. They apparently were lifted from the Equine Endocrinology Group pages rather than current literature, e.g.

https://pubmed.ncbi.nlm.nih.gov/31554591/
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001


celestinefarm
 

Dr. Kellon, I"m confused. The link you posted above says compared to CGIT, sensitivity and specificity of FI for diagnosis of ID were 14.6% and 100% at a cut-off of 20μIU/mL and 63.4% and 87.2% at a cut-off of 5.2μIU/mL, respectively.

MSU's information page states: 
  • Fasted: insulin concentration > 145 pmol/L (20 μU/mL) supports insulin dysregulation.

Are they not saying the same thing, that Insulin dysregulation or resistance is diagnosed at at cutoff of 20?

Dawn Wagstaff and Tipperary   

Saline, MI  2003

Tipperary Case History

Juniper Case history: https://ecir.groups.io/g/CaseHistory/files/Dawn%20and%20Juniper/Case%20history%20Juniper.pdf .


Eleanor Kellon, VMD
 

100% specificity = no false positives. All horses over 20 are IR. However, the low sensitivity of 14.6% = 85.4% of cases are missed by setting the cutoff that high. The rest of that article recommends a much lower ceiling.

Note also that articles confirms the RISQI cutoff. The proxies weren't better than their corrected insulin cutoffs, but they weren't worse either.
--
Eleanor in PA

www.drkellon.com 
EC Owner 2001