Strange hypercalcaemic cat

Re: Strange hypercalcaemic cat

Kara Gibson — Fri, 11 Oct 2013 03:14:07 GMT

Thank you for all the comments! I took some thoracic radiographs (which included the cranial abdomen) and performed an abdominal ultrasound yesterday. This cat has several fluid filled structures within the liver and an opacity evident at this location on the radiograph. I can also see an opacity in the left caudodorsal lung field. I'm awaiting his owners decision about the next step in terms of diagnostics versus palliative care as he is an elderly cat.

Re: Strange hypercalcaemic cat

Kate Richardson — Wed, 09 Oct 2013 16:14:19 GMT

First step always with hypercalcaemia is to repeat and demonstrate persistent hypercalcaemia. Great advice so far from above, cross reference to this thread as well http://www.vetsurgeon.org/forums/t/16466.aspx

[quote user="James Laidlaw"]

Diet? - apparently some of the "all meat/natural" type diets can lead to hypervitaminosis D and hypercalcaemia as a result.

[/quote]

Hypervitaminosis D has been demonstrated with commercial diets.

[quote user="John Flynn"]You can take the appropriate blood samples (with a bit of effort...) for PTH, PTHrp (i've never done this in a cat... but assuming possible?) and Vitamin D[/quote]

Yes you can test PTHrp in cats.

Re: Strange hypercalcaemic cat

John Flynn — Wed, 09 Oct 2013 15:56:55 GMT

[quote user="James Laidlaw"]Diet? - apparently some of the "all meat/natural" type diets can lead to hypervitaminosis D and hypercalcaemia as a result.[/quote]

Phosphorous would be high too if due to all meat diet though would it?

Have seen this in a dog once (I think...) - does it happen in cats also?

Is this different from meat-diet induced hyperparatyroidism?

Re: Strange hypercalcaemic cat

John Flynn — Wed, 09 Oct 2013 14:29:41 GMT

[quote user="Kara Gibson"]I guess the reason I feel confused is because azotaemia preceeded the hypercalcaemia so when I saw this I assumed it was secondary to chronic renal failure but now the azotaemia has resolved.[/quote]

As you say, not always straightforward to distinguish which is the chicken and which is the egg re hypercalcaemia and azotaemia, but I think the picture has become clearer in favour of the hypercalcaemia being the cause of the azotaemia by now:

High ionised calcium
Azotaemia not as severe as would suspect if hypercalcaemia secondary to CKD
Resolution of azotaemia

CKD is a way more common cause of PUPD, dilute urine and azotaemia in a cat than hypercalcaemia is - indeed if you hadn't tested the calcium (and had sampled the cat when it wasn't dehydrated and thus the azotaemia couldn't be pre-renal in origin), I'd have been saying by far most likely to be CKD - goes to show you'll mis-label some cases if don't include calcium here as you did - good effort

[quote user="Kara Gibson"]I have already booked him in for thoracic rads and abdo US but wondered if anyone had any other pearls of wisdom![/quote]

My only pearl would be that ideally I'd get 3 views (2 x lateral and VD) and have them manually-inflated under GA to maximise chances of seeing any lung mets if they are there.

A single sedated chest rad will still stand a reasonable chance of picking up a primary lung neoplasm, so worth doing even if can't get "perfect" set of films.

You can take the appropriate blood samples (with a bit of effort...) for PTH, PTHrp (i've never done this in a cat... but assuming possible?) and Vitamin D and start on preds without worrying about messing up your diagnosis if the patient is sufficiently unwell that you feel waiting for sequential tests is not a good idea but don't want to spend a small fortune on the weird and wonderful prior to getting the imaging done (probably less hastle just to do the imaging though...) Dechra Specialist Labs (formerly CSLS) are who I use and can post you out aprotonin tubes and email info on investigation of hypercalcaemia and sample requirements etc if you think you'll be using them, otherwise EDTA plasma (well-mixed, centrifuged and frozen immediately) and serum (sepatared then frozen) should do fine.

EDIT: was the calcium level on the original sample with azotaemia at least towards the top of the reference interval?

Re: Strange hypercalcaemic cat

James Laidlaw — Wed, 09 Oct 2013 12:06:48 GMT

Diet? - apparently some of the "all meat/natural" type diets can lead to hypervitaminosis D and hypercalcaemia as a result. Would want to confirm persistent hyper Ca before getting too concerned though

Re: Strange hypercalcaemic cat

Kara Gibson — Wed, 09 Oct 2013 11:57:52 GMT

Thanks for the prompt reply!

I guess the reason I feel confused is because azotaemia preceeded the hypercalcaemia so when I saw this I assumed it was secondary to chronic renal failure but now the azotaemia has resolved.

I have already booked him in for thoracic rads and abdo US but wondered if anyone had any other pearls of wisdom!

Re: Strange hypercalcaemic cat

John Flynn — Wed, 09 Oct 2013 11:13:39 GMT

[quote user="Kara Gibson"]Given that this cat is no longer azotaemic do I assume the hypercalcaemia is no longer associated with renal insufficiency[/quote]

Hypercalcaemia causes azotaemia (even in a patient that is not clinically dehydrated) and dilute urine - this is a functional effect of the hypercalcaemia on the kidneys and does not mean that there is any problem with the kidneys themselves.

The IRIS thing (which is more a research thing rather than of use in general clinical practice IMO) is a means of staging confirmed chronic kidney disease rather than being part of the diagnosis; it would not be relevant to a patient with hypercalcaemia.

If the owner does not wish detailed investigations, then I'd send home (perhaps after a drip for 24hrs on saline if required) on prednisolone (perhaps 5mg q12-24hrs initially) and let the cat eat what it wants.

If they want detailed investigations, then I'd think neoplasia top of list and would do survey imaging - someone else will hopefully comment on how one would investigate more thoroughly

[quote user="Kara Gibson"]With this temperature I'm wondering about granulomatous disease.[/quote]

Don't forget to include neoplasia on your list for pyrexia, expecially given the unexplained hypercalcaemia.