Re: Is Matty IR? Questions about sample treatment.

merlin5clougher <clougher@...>

--- In EquineCushings@..., "Christine" <muff747@...> wrote:

I just spoke to my vet and he explained why they were saying he should be fasted - he is governed by the recommendations of how the lab wants the horse to be treated before the blood is drawn. We came to a compromise after reading their literature, that sample could be taken first thing in the morning when he had been fed soaked hay overnight (I make sure he has plenty of soaked hay to last till morning) but not given a feed that morning.
Then we discussed how the sample will be treated once drawn. I thought it had to be processed as quickly as possible in preparation for shipment to the lab - but my vet said it is not that important for the IR test, only for the ACTH test. Is he right? Am I going to risk wasting my time and money again if he treats the sample incorrectly?
Chris/Matty UK 07/09
Hi, Chris -

Here is the information I have been given by one of my labs (Idexx):

ACTH (endogenous) 1 mL frozen EDTA plasma (Lavender top)
ACTH Separate plasma into plain tube, freeze, ship frozen on ice (mandatory)

Collect blood into a chilled lavender top tube, centrifuge and separate plasma into a plain plastic tube & freeze immediately, ship on ice

Glucose 0.5 mL serum(centrifuged SST), or 0.5 mL sodium fluoride/potassium oxalate plasma (Grey top)
GLU Refrigerate, ship on ice Run on receipt, result same day Post prandial values may be elevated, fasting sample strongly recommended
SST must be centrifuged after being allowed 20 minutes to clot, gel must completely separate clot and serum
Grey tops should have at least 1 mL of blood drawn or resulting hemolysis may cause falsely elevated results
Sodium fluoride suppresses but does not stop glucose metabolism

Insulin 1 mL serum (Red top) INS Refrigerate, ship on ice Referred out, please allow 1 week for results
Recommend freezing serum and shipping on ice
If you have questions regarding fasting requirements for insulin testing, please contact one of our pathologists

And here is the link to information on a variety of blood handling recommendations from the same lab:

The long and short is: glucose in particular will continue to be metabolized unless kept chilled/frozen and the serum separated from the clot. If this is not done, the results will be falsely low. I have had the lab tell me that insulin is good, refrigerated, for 48 hours, but they recommend separating, freezing, and sending on ice just to be sure of good quality sample. ACTH must of course be frozen.

The horse is a trickle feeder, not at all like dogs, cats and people, who eat meals separated by longish periods without food. Feeding soaked hay overnight before the blood draw is perfect.

Here is a link to the recommendation for blood handling from Cornell:

This is in the Blood file/Sending Blood to Cornell folder. Good info.

Hope that helps.

EC Support


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