CRF, diabetes insipitus and psychogenic polydipsia

[peterg2]

Hello All,

In December of last year I told you of my cat who went in for a dental cleaning, tooth extraction and the biopsy of a lump. The cat was given an overdose of Metacam 0.4 mg/kg as opposed to 0.2 mg/kg but this was
discovered soon afterwards and she was put on an IV for 24 hours. Here is the original post:

http://www.pets.ca/forum/showthread....bun+creatinine


Anyhow, here is a brief summary with a bit of additional information from January (this was good) and then finally the bad now.


Just prior to surgery a blood panel was done and her bun and creatinine
25.21 and 1.56 respectively (In SI terms 9 and 138 respectively). A week after the IV was withdrawn she was tested again and her bun was down to 22.41 and creatinine was up to 1.92 (normal range of the lab is from 0.57 - 2.00). In SI terms it was 170 on a scale going up to 177. I then heard something which has become a mantra with the vets there and that is normal is normal (which is not correct as high normal is indicative of something and there is indeed creatinine staging re renal disease). Urine Specific Gravity was at 1.035 which I was happy with, albeit not as concentrated as I would have liked.

Go forward a month to January and I had another panel done and this was good. Bun was 21 (SI unit 7.5 mmol/L) and creatinine was 1.40 (SI unit 124 umol/L). I assumed this event was behind me as these were great values.

A couple of weeks ago I started noticing her drinking more than normal. She eats almost exclusively canned - about 1 1/4 5.5 ounces a day with a little bit of added dry. But not much. Six months ago she was eating roughly 2-1 wet to dry. I measured her water intake and whilst varying I would put it at about 160 ccs a day. This still was quite a lot more than what she would drink before. I was getting really nervous now.

Last Friday I took her in for a complete geriatric panel (she is 11) and hopefully a urinalysis. Unfortunately, her bladder was empty and with her previous experience I did not want to leave her there for hours. I received the bloodwork Monday and with the glucose fructosamine test I specified in addition to standard glucose (through prior experience) and the T4 I ruled out diabetes mellitus and hyperthyroidism (what I was hoping for). However, and this was unfasted so bun could be elevated her creatinine was up again 1.92 (lab maximum is 2.0) (SI unit 170 with lab maximum of 177). Her Bun was 26.89 (SI unit 9.6 mmol/L max 13) with a maximum for the lab of 36.41. This is what it was essentially in the first few weeks after the overdose. But in December and January there was no polydipsia.


Clearly a urinalysis and USG needed to be done and I took a sample yesterday and ran it to the vet. They checked it there and the USG was 1.009 which shocked me. It was not the first pee of the day but somehow I don't see it getting much better. No infection was seen.

To me this was all related to the Metacam incident whereas the vet repeated the "normal is normal" with the high creatinine. She felt it might be due to diabetes insipidus (which is quite rare) or perhaps it was psychogenic (compulsive drinking) which I doubted very much as well. Just to add everything else was fine with no hypercalcemia, hypokalemia etc. She had by the way also lost 2 pounds since December but that could be diet (clutching at straws time) but she was still chubby at 12 pounds.

Anybody have any ideas on this? I will have another urinalysis done, either tomorrow or on Monday and try and make sure it is the first of the day but with the drinking I do not see it changing much.

All replies most appreciated.

Peter