Isn't Calcium a Good Thing??

Sunday I mentioned that one of my cats had some blood work that showed an elevated calcium level. I'm sure most people wouldn't think that was a big deal. Calcium is important and we all know it's "good for us." But too much of ANYTHING is bad. In the case of calcium, it can signal bad things and if it remains elevated, can CAUSE bad things.


We call elevated blood calcium hypercalcemia. In dogs this is generally a level above 12.0 mg/dl (milligrams/deciliter) and in cats, above11.0 mg/dl.  What is measured in a pet's blood work is the total calcium. The level can be affected by some things:
- dehydration (from many causes)
- blood protein levels (notably albumin)
- fat in the blood (lipemia)
- growth (it IS normally elevated some in growing kittens and   
             puppies)


In a normal, healthy animal, and barring any of the above listed situations, the pet is able to maintain calcium within a specific range in the blood. It doesn't matter what they eat, how much of it they eat, if they are athletic or not, etc. This is how the system works:

From a human resource but it's the same in our pets.

Very often, there are no signs in these pets. Sometimes I hear that a pet is drinking and urinating a lot (this is because the body is ATTEMPTING to bring this level down but cannot). 


So we often see it because we are doing screening blood work or we are working on another problem. When I see an elevated Ca level, I do one of two things depending on the amount of elevation and how the pet is doing: repeat blood work in a few weeks/months or go further with diagnostics ( more extensive bloodwork, xrays/ultrasound). 


The first NEXT test is a more involved blood panel that measures parathyroid levels (PTH) and ionized Ca (these things will tell us if the body's feedback system for controlling Ca levels is working ok). 


The reason is that outside of one of those benign things causing Ca to rise, most of the time there is a pathologic or bad reason. The most common reason in pets is cancer. There ARE some cases of parathyroid problems (a small gland that is involved in control of Ca levels). 


But why does cancer cause this? Some tumors make a molecule that acts just like PTH. The most common ones that do this are: lymphomas and anal sac adenocarcinomas (hence the reason all dogs with this should get a rectal exam). A few other, less common cancers do this too.


The other thing of concern is that having an elevated calcium, especially as it gets a few points above normal, can result in kidney damage AND calcification of organs leading to systemic organ failure.


So we need to do things if your pet has an elevated calcium level: 
1. Find out why - this will involve expense and probable multiple hospital visits
2. Bring this level down as soon as we can - in some cases, we will use oral steroids to help this, in cases where the animal may be going to chemotherapy, we have to hold off on this and use fluids and other drugs


In Skittles' case, she has, as is more common in cats, idiopathic hypercalcemia (meaning we don't know why).  This does happen in some cats, they "think" because of some little pumps that move Ca in and out of cells being abnormal or absent in some cases. In her case, it's not high enough to cause damage but it's something I keep an eye on with yearly blood work.