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Elevated creatinine w/normal BUN?

post #1 of 15
Thread Starter 
Hi everyone,

Does anyone know what could cause elevated creatinine with normal BUN? I'm kind of confused. I'll be talking to the vet more in depth next week, but I'm just curious about it. The bloodwork this time didn't include a CBC since we were running it to re-check her calcium (which is suddenly high again, after 2 years of being back within the normal range).

Her BUN is 21 (ref 10-30) and creatinine is 2.1 (ref 0.3-1.6). Phosphorous is 4.0 (ref 3.4-8.5), so that's low-normal. Everything else is within normal range except for total calcium, which is 15.0 (ref 8-11.8). I know that's quite high, and additional testing is in order, but I'm just curious about the BUN/creatinine thing. Does anyone have any ideas?

post #2 of 15
Info about creatinine

Creatinine is the end product of phosphocreatine metabolism, which is important in muscle contractions. High levels indicate kidney failure or disease, dehydration, shock, certain toxin ingestions, poor circulation to the kidneys and urinary obstruction. Low levels indicate liver disease or starvation.
In other articles I've seen arthritis, hyperthyroidism and diabetes also mentioned with elevated levels.

Good calcium related info here

I'd like to ask you if I may, is your kitty on some kind of special/restricted diet? What about a supplement containing vit D? Is she taking calcitriol?
post #3 of 15

This is very good info about hypercalcemia
post #4 of 15
Normally, I wouldn't respond to this kind of question, because I don't know anything about "bun" or "creatinine" data and what implications they have for cats.

However, when my cats were affected by the 2007 pet food poisoning (melamine and cyanuric acid), that's exactly how their tests came back: normal/high-normal bun numbers with high creatinine numbers.

Not something to alarm you with, just something to be aware of as you collect information.
post #5 of 15
Following up on this......In addition to other toxins, medications can also be toxic and elevate creatinine levels. Since you have a problem with creatinine and hypercalcemia as well, JennyJen, please give us more info, let us know what meds your kitty is taking.
post #6 of 15
Thread Starter 
Thanks for the info, everyone. Bailey's history is a complex one. She's 14 years old. The only medication she's on is lactulose. Her food contains vitamin D, but she's not on any supplements. I did think that lactulose may have been causing her elevated calcium, but after cutting her lactulose dose in half over 2 months, her calcium actually went up. I'm in the process of digging through her records in an attempt to find a pattern, but here's the abridged version of the story:

In May of 2007, elevated calcium and creatinine were noted during a trip to the emergency vet after she stopped eating. Creatinine went back to normal after getting IV fluids though. Over the next 3 months, we did just about every possible diagnostic test to find the cause. After ruling everything out, the only answer was that she had idiopathic hypercalcemia. We were about to start treating her with prednisone when her calcium levels (total and ionized) went down to almost normal level and stabilized, so it was decided not to treat it and monitor her. All of her blood work was normal (including calcium, which eventually got down to high-normal) until October of 2008, when she was diagnosed with hyperthyroidism (all other values were normal). In December of 2008, she received radioiodine treatment for hyperthyroidism. In January of 2009, follow up blood work showed normal thyroid hormone levels, and everything else was normal as well. In March of 2009, she had dental work done and pre-op blood work was all normal. In April, Bailey had a bad bout of constipation, so after getting an enema at the vet, I increased her lactulose. In August of 2009, routine blood work showed elevated total calcium (everything else was normal). I wondered if the increased lactulose may have caused this since I had previously wondered if there had been a connection back in 2007, so I decided to decrease her lactulose and have her calcium re-checked in a couple months. Now it's November of 2009, and her total calcium has gone up even more, along with the elevated creatinine.

I plan to have a complete workup done again, along with ionized calcium. Her ionized calcium level should give us an idea of where to go next. This is just confusing. All the diagnostic tests done in 2007 ruled out every known cause, so it's just really weird. I'm trying to think of anything I've done differently since January of 2009, which was the last time her calcium tested normal, and I can't think of anything. She's been on the same dry food since 2007, and she's always gotten a variety of different wet food. I guess it could be something to do with her wet food, but I'm not sure which one.

One thing I find interesting is that the first time we found her calcium to be elevated in May of 2007, she had completely stopped eating. Her total calcium was the highest it had ever been until now, yet I haven't noticed any obvious difference in her eating habits. An ionized calcium test might shed a little more light on this. I'm just at a loss, and I can't believe this is happening again.

Thanks again everyone! Hopefully I'll know more in the near future.
post #7 of 15
Thread Starter 
Well, after going through her lab results from the past few years, I'm still at a loss. I'm going to call the vet tomorrow and try to get her in ASAP for a complete workup with an ionized calcium test and ask about the possibility of excess vitamin D. In the meantime, if anyone has any other suggestions, I'd really appreciate hearing them. I'm telling you, this kitty is a medical mystery!
post #8 of 15
Thread Starter 
Well, Bailey's ionized calcium is 1.64, which is WAY high. Now I'm officially freaking out, and I feel like I'm going to throw up. Looks like we'll be starting the entire process over again.
post #9 of 15
and relax Bailey can sense your worry and that will not help her...

Have you discussed these results throughly with your vet? thought about a second opnion ?

other than blood work any tests done >?
post #10 of 15
Thread Starter 
We went through an extensive series of tests in 2007 (PTH/PTHrP, x-rays, ultrasounds, bone marrow aspirate, elspar trial) and came to the idiopathic conclusion. But her total and ionized calcium eventually came down to within normal limits without treatment. Now it's back all of a sudden. It looks like the next thing will be the PTH/PTHrP test again. I just hate the idea of putting her through this all over again. I wish we could just say it's idiopathic and treat it as such, but it's just too weird that her calcium levels were normal for 2 years and now all of a sudden, they're through the roof. So I just don't really know what to do. If we don't bring her calcium down SOON, then there's a pretty high risk of it ruining her kidneys. BUT I don't know if we should start using medication to bring her calcium down without trying to find the cause (or at least eliminating potential causes) first. But if we spend too much time looking for the cause, then she could end up with renal failure. I don't know what to do!!
post #11 of 15
I would ask the vet for the nearest cat specialist ... Unfortunately 2 years makes those tests invalid, most vets will only take six months or less .

Dumb question time : what is she eating>? brand and type.... does she go outside ? if yes supervised or unsupervised ?

I am like you and want the cause but since this is a second occurence I would likely start the meds and continue testing
post #12 of 15
Thread Starter 
Yeah, the vet said he is going to consult with the local internal medicine specialist. She is indoor only. She gets Hill's I/D dry (I know, I know, but that's what has worked for her) and a variety of canned food including Avoderm, Taste of the Wild, Weruva, Wellness, and Halo. I feel silly saying this, but could it have something to do with the tap water? Or maybe something to do with her cat litter? She's been using World's Best Litter since last December.

Sharky, do you think treating her hypercalcemia with medication could skew test results though?
post #13 of 15
I am NOT a vet ... so I would guess meds could sqew that but if you get it to a safe zone you will have more time with her to figure it out without other complications like kidney failure.
There are some studies relating to tap water , are you on a well?
Did you change flea control? New carpet?

So she has tummy issues with DRY foods but it fine with many wets?
post #14 of 15
Thread Starter 
I totally agree with you about getting her in a safe zone. I talked to the vet a little while ago, and we agreed that we should do the PTH/PTHrP test again. I mentioned starting treatment to avoid the complications that hypercalcemia can cause. He was receptive and said he wants to get the sample for the PTH/PTHrP test first, and that we could start treatment immediately after that. We'll talk about it more Monday, but that sounds like the best thing to do right now. Monday is the earliest we can do it due to shipping requirements for the sample and Thursday being a holiday.

No new flea treatment or carpet. We're not on a well, so it's city water, but it does seem to have a high mineral content.

As far as the food goes, she's a pretty finicky eater in general, which is why we rotate her wet food so much. I had tried multiple times to get her on wet food only, but I just couldn't get her to transition. I tried transitioning her slowly, giving her wet food multiple times a day, and slowly reducing her dry food, but I just couldn't get her to eat enough no matter what. The reason she's been on the I/D dry for a few years is because before that, I couldn't get her to eat ANY food for more than a couple weeks (that and/or she would puke it up, including wet food). She's been vomiting A LOT less since on the I/D Dry and she still eats it, so I haven't dared to change it.

Sharky, thank you for your input. I really appreciate it and the questions you ask. It's helpful to get some different ideas to consider when I'm practically banging my head against a wall.
post #15 of 15
many areas have a water district that will test water for free or they have the most recent tests on the water may be something to look into. Your very welcome
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