Bile Acids Test

[Cheri McDonald]

Briar is going in next week for her Bile Acids Test now that she has been on the pheno for about 6 months. Question is there seems to be a urine test and a blood test. The blood test has to be fasting and that is hard to do when she has to have the pheno with food. I have a call out to the vet to see what test they will do. Also she has recommend every six months to have this done and I recently read that it should be done every 3 to 4 months. Suggestions?

[AK dog doc]

Bile acids are done as a test of liver *function*. You can also test liver enzymes, but these can be abnormal for a variety of reasons which may or may not relate to liver function, ie, the ability of the liver to do its job. So if you're looking to find out if the liver is able to do its job, bile acids are the better test.

 

Phenobarbital is one of many drugs that is metabolised by the liver. Some dogs live very well on pheno (and other medications) for many many years. Some have trouble metabolising them, and will consequently have liver enzyme elevations and/or changes in hepatic function.

 

The FDA has regulations about monitoring of some of these drugs, which means that vets have to honor that schedule if they want to keep their DEA liscensure. Right now the guidelines on Pheno are every six months. We (meaning the vets at our clinc) usually do alternating tests - liver enzymes one time, pheno levels the next - and in general I reserve bile acids for testing if I start seeing enzyme levels come up or for other reasons have concern about liver function. However, doing bile acids is certainly an alternative. My *personal* preference is to do the liver enzymes, because my opinion is that I may see liver enzymes elevating BEFORE I see changes in liver function, which would alert me to smaller changes than the bile acids, ie, changes sufficient to release enzymes into the blood stream, but insufficient to injure the ability of the liver as a whole to do its job. The liver has a tremendous reserve capacity (in other words, it can take a pretty big hit before it starts losing function or goes into failure). Because of this, my thought is that I'd prefer to catch the injury BEFORE it goes far enough to damage function, and I feel that checking enzymes is a reasonable way to do this. However, bear in mind that my opinion isn't the only valid one in the world, and this is just what works best in my hands. That doesn't mean there aren't other right ways to do things. (Liver enzymes can be done on an un-fasted dog, though I personally prefer for them to have not eaten for 3 or 4 hours before the test, in order to avoid having a high post-feeding fat content in the blood, which can cause false readings).

 

I currently hold my testing to every 6 months UNLESS I see a problem which I feel needs closer monitoring. However, if you and/or your vet feel more comfortable with every three to four months, that is by no means wrong; certainly it would allow you to catch any changes sooner, if they are occurring. Again, this is my opinion, not the word of God, and we should always bear in mind that I'm a general practice vet - not a boarded neurologist or internal medicine specialist.

 

Can you be more specific about the urine test that your vet discussed? There are lots of things to be done with urine, not sure which one you're referring to here.

[Cheri McDonald]

Here is something that I read recently regarding testing.

 

"URINE BILE ACIDS TESTING

 

ADVANTAGES

There are several advantages of urine bile acids testing over blood serum bile acids measurement:

1. This test requires no fasting.

2. One urine sample is all that is needed: no double blood draws.

3. The urine sample can be collected at any time--no need to go to the vet's office unless you have problems collecting the sample yourself.

 

4. This test is less expensive than pre- and post- bile acid blood draws, which require a vet visit in addition to the test fee.

5. The test is as sensitive as the pre- and post- bile acid blood draws."

 

The cost thing is not a factor as both dogs have health insurance. Just worried about the fasting and having to give her the pheno. Whatever the best method is what we would want to do. Thanks for you information and I will ask our vet about the other testing.