How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Richard Carter — Wed, 12 Sep 2018 17:54:21 GMT

anyone think in these chronically stressed dogs that one might get a 'type 2 exhaustion' type effect on the adrenals which would explain the almost miraculous recovery on even small amt cortisone supplementation? (just thinking about type 2 diabetes where is not due to loss of cells, just cannot keep up production)

Think the low cortisol reading you already have in a stressed dog is already significant

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Martin Atkinson — Wed, 12 Sep 2018 14:19:39 GMT

So its not going to be a classic Addisonian but as suggested in a very stressed normal dog you would expect a stress leucogram and mild hyperglycaemia so still possible its atypical glucocorticoid only deficient Addisons.

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Aisling McGrath — Wed, 12 Sep 2018 11:35:45 GMT

Na:K ratio was 40

Eosinophil and lymphocyte counts both normal - both roughly in mid reference range (on in house lasercyte)

Glucose 7, so completely normal

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Emily Rainbow — Tue, 11 Sep 2018 22:51:39 GMT

Also make sure you send your ACTH stim to the lab rather than using in-house testing as there’s less cross reaction if had previous dexamethasone administration.

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Martin Atkinson — Tue, 11 Sep 2018 17:24:59 GMT

[quote user="Aisling McGrath"]So I took bloods for in house haem/chem17/lyte. Only abnormalities mild to moderate haemoconcentraion[/quote]What was the Na:K ratio, they may have been individually normal but IME a Na:K ratio of <30 is suspicious, <27 very suspicious, <24 almost certainly Addisonian. Could be its glucocorticoid deficient only so take a close look at the haematology: did you do a separate eosinophil and lymphocyte count - you'd expect an eosinopaenia and lymphopaenia in a stressed dog so normal values may still be abnormal. Equally, if the glucose is normal is it low normal? You need to know these as your baseline 'cus if it is Addisonian an ACTH stim test is not a lot of use for monitoring, apart from also being a faff and expensive to keep repeating.

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Aisling McGrath — Tue, 11 Sep 2018 15:43:43 GMT

So just to update you all, and thanks for the input so far, after giving the dog dex only on friday night (so no more preovmax), he was fantastic for around 48 hours, then began to be lethargic and off food again, and stools looser and vomited once.

He's a mad stressy hairy little dog (weird yorkie cross?) and was super stressed Friday evening at his c/u, but his heart rate was 80 (!!!). So I took bloods for in house haem/chem17/lyte. Only abnormalities mild to moderate haemoconcentraion - he got so stressed for bloods I'm convinced his spleen must have contracted to cause that, as he appeared in no way clinically dehydrated. Also his amylase was low, but everything else fine.

I took blood for a basal cortisol, which has come back today as low (<10).

Having spoken to IDEXX, they have advised that given the last dex was friday, it should be almost completely out of his system by now, so I should be fine to do an ACTH stim test tomorrow, which is my plan...

Gut feeling is Addissons.... but could be proved wrong!

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Anthony Dennison — Mon, 10 Sep 2018 19:38:09 GMT

[quote user="robloxley"]Maybe I'm thinking of some of the less acute addisonian crisis cases, more grumbling symptoms, where adding a basal cortisol to a standard profile is somewhat cheaper and easier than ACTH stim[/quote]

I would say the grumbling ones are harder to interpret. I'm more likely to do a basal cortisol only in a suspected addisonian crisis.

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Rob Loxley — Mon, 10 Sep 2018 19:26:28 GMT

[quote user="Anthony Dennison"]

[quote user="robloxley"] However I'd consider running a basal cortisol as a normal (about 50 I think, more precisely) will rule out Addison's[/quote]

When I've done this through Idexx they normally say anything over 40 rules out Addisons. I would prefer an ACTH stim straight off.

[/quote]

Maybe I'm thinking of some of the less acute addisonian crisis cases, more grumbling symptoms, where adding a basal cortisol to a standard profile is somewhat cheaper and easier than ACTH stim

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Anthony Dennison — Mon, 10 Sep 2018 10:18:55 GMT

[quote user="robloxley"] However I'd consider running a basal cortisol as a normal (about 50 I think, more precisely) will rule out Addison's[/quote]

When I've done this through Idexx they normally say anything over 40 rules out Addisons. I would prefer an ACTH stim straight off.

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Martin Atkinson — Mon, 10 Sep 2018 09:08:58 GMT

My understanding is that a single dose of dex will not affect the ACTH stim test. There are occasions when in an emergency situation a patient has to be given some steroids and the test is a secondary consideration so dex would be best choice in these situations. But Addisons should be flagging with electrolytes (albeit some glucocorticoid deficient only cases may not show a change in these) and lack of a stress leucogram (but your dex may have affected that).

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

Rob Loxley — Sat, 08 Sep 2018 13:06:37 GMT

[quote user="Aisling McGrath"]Any input appreciated[/quote]

My understanding is dex won't cross react with the cortisol assay but may suppress the HPA. However I'd consider running a basal cortisol as a normal (about 50 I think, more precisely) will rule out Addison's , and you may be able to get this run before you get a chance to do an ACTH stim (if we take friday evening we usually get results back saturday, even if sent in post saturday often back monday before your in-house biochem). If low basal cortisol, then you still need an ACTH stim to confirm. Have you checked electrolytes.

Equally he may have responded to the prevomax, so interesting to see the response to just dex?

RE: How long after Dex admin can I do an ACTH stim test on suspect Addissons dog?

JenRowland — Sat, 08 Sep 2018 11:25:47 GMT

There is a great article on Addisons by Ian Ramsey in this week's In Practice. Have copied the relevant part in case you don't have access. Hope this helps!

Dealing with the patient that has received steroids
Sometimes clinicians are presented with a case of suspected hypoadrenocorticism
that has been treated with one dose of dexamethasone. In this situation, patients
should be supported with symptomatic treatment (such as fluid therapy) and an
adrenocorticotrophic hormone (ACTH) test should be performed 36 hours later.
Hypothalamic–pituitary–adrenal (HPA) axis suppression should have resolved
by this time but results should still be interpreted with caution. Longer courses
of steroids will have more effects that will last longer. Even topical steroid-
containing preparations have the potential to cause HPA axis suppression. Studies
have shown that 35 days of prednisolone at 0.5 mg/kg every 12 hours will suppress
the ACTH stimulation test for a further month after cessation of the steroid
and for the first two weeks this response could easily be confused with that of
hypoadrenocorticism. A single dose of a long-acting methylprednisolone injection
will affect ACTH stimulation tests for up to five weeks.
In addition, if steroids have been given very recently to any animal then it is worth
remembering that some (eg, hydrocortisone and prednisolone) cross-react in the
cortisol assay and therefore give false increases. For this reason, prednisolone
should not be given during the 24 hours before an ACTH stimulation test.