Cushings question

Re: Cushings question

Martin Atkinson — Wed, 08 May 2013 17:36:26 GMT

[quote user="Sarah Wheatley"]When would you do an ACTH stim test again? and When would you start trilostane again?[/quote] This is the first time I've looked at this thread so unless some posts have been deleted I'm rather intrigued as to where the sudden excitement about bradycardia came from as there is no mention in the OP. As for the quoted question: NOW! How can you rely on a test you don't know the result for and relied on someone else's interpretation especially with such a dramatic response to Trilostane therapy?

Re: Cushings question

Christopher Saul — Mon, 06 May 2013 19:39:13 GMT

[quote user="David Mills"]http://www.ncbi.nlm.nih.gov/pmc/articles/PMC425359[/quote]

Lifted straight from the text of this article:-

.Conversely, dexamethasone had no direct effect on potassium secretion by single microperfused tubules, but it caused a sharp increase in urinary flow and sodium excretion, and secondarily enhanced urinary potassium

[and this was in rats]

In other words its effectiveness in this matter is secondary to increasing diuresis; something that can be achieved by fluids. I do often give a one-off dex dose to addisonians but only as part of a treatment regime including aggressive fluids. I would also normally follow up hydrocortisone which has more mineralocorticoid activity, and of course fludroortisone once the patient is euvolaemic and able to accept oral meds.....

Re: Cushings question

David Mills — Mon, 06 May 2013 17:18:34 GMT

Interestingly, dex does appear to increase potassium excretion by the kidney:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC425359/

Although it may well be attemuated by any hypovolaemia.

Re hyperkalaemia generally, the question is surely when to treat. Serumm potassium has porr correlation with ECG changes, bradycardia is inconsistent, and ECG changes are highly variable and may well be obscured by sympathetic (clinic) overdrive. Bradycardia in this scheme may well be the most sensitive indicator of hyperkalaemia that definitely requires treatment because of its clinical significance. With correctly functioning renal system, normokalaemia is quickly restored IME.

Re: Cushings question

Christopher Saul — Mon, 06 May 2013 15:54:54 GMT

Hello Michael

[quote user="Michael Woodhouse"]All I was trying to ascertain was if the dog was an emergency or not.[/quote]

It's a really nice idea, I agree it would be lovely to use this but I should point out that only around 25% hyperkalaemics will present with a noticeable bradycardia, so this is a very insensitive test for of making that decision. You'll miss 75% of hyperkalaemic patients in this way. Moreover if it is does have a hyperkalaemic bradycardia then it really may need aggressive emergency fluid resuscitation.

I'm really sorry if I misinterpreted your original post Michael, I didn't mean to upset you or cast doubt on your awareness of this but you did say

[quote user="Michael Woodhouse"]

If it had a daft low HR then I'd see it and give it a small shot of dex.

[/quote]

Chris

Re: Cushings question

Sarah Jane Denny — Mon, 06 May 2013 15:31:52 GMT

Hello Again,

Thank you all for your very helpful answers.

Just to update you. The Cushings dog presented that night, BAR, HR 80 BPM in consult, pulses normal, hydration normal, mildly HyperK, stopped vetoryl, home. Have kept in touch by phone since, much brighter since stopping meds according to O. Plan that they should have ACTH stim/meds reviewed early this week. The original dose was high I suppose and pushing this dog towards an Addisoninan state. But also possibly another underlying cause which I have discussed with the owner.

The owner would need to be very reliable for me to trust them to take a heart rate correctly in this particular situation. An incorrect measurement and misunderstanding over the phone could lead to a very sick dog being unattended overnight. Some owners are wonderful with medical matters. Others are terrified at any intervention apart from feeding, walking and picking up 'poo' and so would not like to put in a position to have to measure a heart rate. But if I had a client that I knew very well, and who could be relied on, then I might ask them to check the heart rate I suppose, but would probably see the dog anyway.

PS Sorry Micheal, seem to have done something to your post, 'verfied it' by accident!

Re: Cushings question

Michael Woodhouse — Sat, 04 May 2013 23:52:25 GMT

[quote user="Christopher Saul"]Really? A profound bradycardia would imply hyperkalaemia and an addisonian crisis. Dexamethasone, though a powerful glucocorticoid, has virtually no mineralocorticoid activity and thus on its own is not an effective treatment for a crisis. Whilst I would give dexamethosone as part of a treatment plan for an addisonian crisis (though if owners could afford I would choose something with more mineralocorticoid activity eg hydrocortisone or methylprednisolone), the most important single treatment (assuming the patient is in crisis) is FLUIDS. I normally give a bolus of 1/3 shock dose over an hour then reassess at that point. Quite frequently fluid resuscitation will all but correct the hyperkalaemia but if this remains stubborn then I generally go for insulin and glucose.[/quote]

All I was trying to ascertain was if the dog was an emergency or not. When starting a dog on Vetoryl I always make sure the owners have a dose of pred so they can administer it should anything 'weird' happen.

Perfectly aware they need fluids, if in a true crisis and hyper K+.

Re: Cushings question

Christopher Saul — Sat, 04 May 2013 21:42:37 GMT

Andy makes a nice point; definitely worth at least checking the original results. Sarah, feel free to post them here if you have the results to hand....

I've corrected a couple of typos in my post - I of course meant over-supression not overstimulation, and I also meant that bradycardia is not very specific for HYPERkalaemia

Re: Cushings question

Andrew Kent — Sat, 04 May 2013 18:10:21 GMT

My first reaction to dogs who do odd things on trilostane is to revisit whether the diagnosis is correct. Hyperplasia isn't classic liver change with HA so I would go back through the diagnostics. Were the adrenals visualised on ultrasound and were they abnormal? Was a urinalysis done? And how convincing was the ACTH? If any doubt then more investigations (eg LDDST) may be a good idea!

Re: Cushings question

Christopher Saul — Sat, 04 May 2013 13:05:35 GMT

[quote user="Sarah Wheatley"]

What dose regime of trilostane do you usually start on?

[/quote]

The data sheet starting dose of 3-6mg/Kg is very high, we would normally advise a starting dose of 2-2.5mg/kg/day and titrate the dose as necessary. Whilst the majority of cases will need higher doses than this to achieve ultimate control, even at 2mg/kg/day, there is the potential to cause iatrogenic hypoadrenocorticism in some cases

Trilostane has been associated (albeit rarely) with adrenocortical necrosis so this is not a benign treatment.

I agree that over-supression is likely but of course you cannot eliminate other causes (hypoglycaemia? heart failure?) until you see the patient; I would suggest a full physical examination (paying particular attention to pulse quality) as well as electrolytes, biochem and blood gasses if available.

[quote user="Sarah Wheatley"]Can over-suppression happen this quickly-24hrs on 2mg/kg dose? [/quote]

It does seem very quick, I agree, but not impossible so hence why phys exam and electrolytes etc so important

[quote user="Sarah Wheatley"]

When would you do an ACTH stim test again? and When would you start trilostane again?

[/quote]

I guess if it depends on if your physical exam reveals any evidence for another pathology, but assuming it doesn't then I would do one now, before starting any steroids. As for when I would restart, depends on the ACTH stim result I guess....

Michael's approach of asking the owner to count the heart rate is very trusting of the owner's ability to accurately assess the cardiovascular status of his/her pet. Personally I wouldn't trust an owner I'd never met, especially as bradycardia is not very sensitive for hyperkalaemia.

[quote user="Michael Woodhouse"]if it had a daft low HR then I'd see it and give it a small shot of dex.[/quote]

Really? A profound bradycardia would imply hyperkalaemia and an addisonian crisis. Dexamethasone, though a powerful glucocorticoid, has virtually no mineralocorticoid activity and thus on its own is not an effective treatment for a crisis. Whilst I would give dexamethosone as part of a treatment plan for an addisonian crisis (though if owners could afford I would choose something with more mineralocorticoid activity eg hydrocortisone or methylprednisolone), the most important single treatment (assuming the patient is in crisis) is FLUIDS. I normally give a bolus of 1/3 shock dose over an hour then reassess at that point. Quite frequently fluid resuscitation will all but correct the hyperkalaemia but if this remains stubborn then I generally go for insulin and glucose.

Hope this helps

Chris

Re: Cushings question

Michael Woodhouse — Sat, 04 May 2013 00:16:11 GMT

If an owner rang me now and asked about the dog I'd get them to put their hand on the dog's chest and count the heart rate. As long as dog not profoundly bradycardic and not collapsed, give no more pills and come to surgery tomorrow. If it had a daft low HR then I'd see it and give it a small shot of dex.

Worry what else may be wrong after the bank holiday.