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kitty update
I asked if we could just jump to the more expensive, conclusive test and be done, but that wouldn't tell us if there's a parathyroid problem and it wouldn't be good to ignore that if he does have a problem. Oh well.
The vet is also suspicious that it might turn out that Erik just has high calcium levels and nothing's really wrong. She bases this suspicion on the fact that two years ago (first data we have) his blood-calcium level was 12.8 (something) and this time it was 13.1 -- a slight rise, but not a big one and he hasn't been sick in the meantime. (Except, I pointed out, he's been losing weight. And the cats I know who have had kidney failure have also lost significant weight. But she's not convinced that's relevant here.) Normal blood-calcium level is 8.2 to 10.8, she said.
I feel confident that the vet is doing her best to try to explain things to me, and that she's showing more concern than I'm used to from vets, but I still feel like I'm not completely getting this. I think I need to spend more time with Veterinary Partner, but I also need to ask her to write down the names of the tests she's doing and the measures she's looking for.
I have an appointment for Monday evening for her to draw more blood. (I asked if she could draw enough for both tests and set some of it aside, rather than making me come in again if we don't like the results of the first test, but she doesn't know if blood can be held that long.)
A short treatise on hypercalcemia :-)
OK -
most common causes of mild hypercalcemia noted on repeated samples
1) Early renal failure.
Note: there has to be loss of >75% of kidney function before there are bloodwork changes. The urine specific gravity (concentration) will drop first. A urine specific gravity of <1.030 (or ten-thirty) would be suspicious. Heska (a vet specialty company) makes a test kit called ERD (for early renal disease detection ... looks for a specific protein in the urine that is an early indicator of kidney problems)
2) Hyperthyroidism
Overactive thyroid (I think this one I mentioned before). Likely one of the followup tests being considered is T4 (total thyroid hormone) and/or fT4 (free thyroid hormone ... the part that is available for the cells in the body to use). The fT4 tends to rise before the T4; it costs a bit more that the T4, and takes two to three days to get a result (due to the test technique).
3) Vitamin D overdose (but unless he's sneaking pills behind your back...)
4) Primary hyperparathyroidism (overactive parathyroids)
5) Hypoadrenocorticism (underactive adrenal glands - very rare in cats!)
6) granulomatous diseases (hmmm ... ask if they've done a check for FIP - feline infectious peritonitis - without other changes in the bloodwork, and a cat who seems healthy otherwise, it's not likely, but it's the leading "granulomatous disease that comes to mind .... and it can be potentially contagious to other cats in the house, so have the screening done, if not done already)
7) Neoplasia (cancer). Not likely if the Ca level has been up for 2 years already :-) Also, the Ca levels tend to be higher with cancer that we're seeing here (well over 13; elevations in the 10 to 13 range were most commonly associated with kidney problems)
8) Calcium oxalate urinary stones have been associated with hypercalcemia (I suspect your vet is going to take a good, long, hard look at the urine, again, as the crystals may be found in the urine.)
9) the ever-popular "idiopathic". Means it's there, but we don't know what's causing it. There are some (small) studies coming up in my search that indicate an acidifying diet (commonly used for cats with a history of urinary crystals (struvite, not calcium oxalate!)) may lead to hyperCa; in some cats, a diet switch may clear up the problem. Also, it seems some cats with idiopathic hyperCa responded to treatment with prednisone :-)
Hope this helps :-)
_M_
Re: A short treatise on hypercalcemia :-)
If that comes back normal, then there's a possible kidney problem and a different (more expensive) test to investigate.
I suspect she might be looking at sending in a calcium profile to Univ of Mich lab - they have a panel that looks at total and ionized Ca, as well as parathyroid hormone.
As some point, if there's blood or protein showing up on the routine urine screens, they may want to get x-rays or an ultrasound to rule out hephroliths (stones in the kidneys, as opposed to in the bladder (bladder stones are much more common in animals).
_M_
Re: A short treatise on hypercalcemia :-)
1) Early renal failure.
Note: there has to be loss of >75% of kidney function before there are bloodwork changes.
She told me the 75% figure when calling with the results of the bloodwork, too. I asked how we would know if not from the bloodwork, and that's when she asked for the urine sample. But we still don't know, it seems. It sounds like the approach is "eliminate everything else first and then worry about kidneys", which is a little unsettling. I'll ask about that ERD test you mentioned. (I'll also find out what the specific gravity actually was and record it here; I didn't get that number when we talked. Actually, I'll bet I can get that from the office without specifically needing to talk with the vet.)
The reason I have a two-year-old calcium reading at all is that about two years ago I noticed that Erik was having (uncharacteristic) trouble jumping -- he couldn't jump as high and he was sometimes just plain missing his target, which never happened before that I saw. I wondered if he had injured a back leg somehow and took him to the vet. The vet found some swelling in his joints and put him on prednizone for a couple weeks, which cleared up the problem. But he also took an X-ray to rull out a hairline fracture or the like, and that X-ray happened to catch the kidneys as well, and he noticed small amounts of calcium buildup in the kidneys. (Is this the early stages of kidney stones, I wonder?) He said that wasn't necessarily worrisome but we should check his blood calcium levels, and that's when the first test was done. He also put Erik on a new diet at that time, which I gathered was low-calcium; the bag actually says "for renal failure" even though that's not what he has. (The brand is IVD, something you can only get through vets. I asked my current vet if that was appropriate food for him and she thought it was probably ok though she wouldn't have thought to prescribe it herself.)
That vet I saw two years ago is no longer available. :-(
3) Vitamin D overdose (but unless he's sneaking pills behind your back...)
She actually mentioned that the Vitamin D levels in the blood were normal, though I didn't know why that was significant at the time. (And hey, if he's sneaking pills he should share them with me; FitDay thinks I'm a little low on Vitamin D...)
Based on our conversations, I think she's focusing primarily on hyperthyroidism and hyperparathyroidism right now.
ask if they've done a check for FIP - feline infectious peritonitis
Thanks for the tip. I will ask about this, especially as there are two other cats in the house.
Neoplasia (cancer). Not likely if the Ca level has been up for 2 years already :-)
Yeah, she said much the same thing. :-)
the ever-popular "idiopathic". Means it's there, but we don't know what's causing it.
I could live with that (not that I get a vote :-) ), especially if she can suggest ways to keep it from getting out of hand and ways to monitor the kidneys before the 75% failure that causes it to show up on a blood test.
I guess I'll get my next round of data next week.
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172 matches when I searched on "hypercalcemia causes" and limited teh search to cats.
I love VIN (a vets-only membership service I belong to with an online searchable database)!
_M_
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