In the last edition of “At The Laboratory With Your Pet’s Doctor,” we studied the details of the complete blood count. Today, we will look at a battery of tests called the chemistry profile.

In the complete blood count, we were examining physical bodies, tiny little cells that circulate in the bloodstream. With the chemistry profile, we’re learning about the things in the bloodstream at the molecular level, truly the metabolic function of the body.

You’ve probably heard the doctors on “ER” or other hospital shows call for a Chem 7. This is a tiny little panel of chemistry tests that tells us only about 7 parameters.

What the laboratory we use calls a SuperChemistry Profile includes 26 parameters. Let’s look at them one by one.

Two tests tell us about how much waste product the kidneys are (or are not) removing from the blood. BUN, or blood urea nitrogen, measures nitrogen molecules broken off from protein molecules we’ve eaten. This nitrogen has to be removed from the blood as a waste item, or it becomes toxic.

Likewise, creatinine is a waste item produced by muscles that is removed by the kidneys. Together, the results of these two measurements tell us whether waste that is supposed to be removed by the kidneys is being removed from the blood quickly enough.

Now let’s look at liver tests. Routine screening tests do not test the function or capacity of the liver to do its job. All they do is tell us whether the liver has been damaged. First, let’s look at ALT, an important liver enzyme. Enzymes, by the way, are ingredients that help a chemical function to occur.

If your pet’s doctor finds that the chemistry profile is showing him that the ALT is elevated, he knows that the liver has been damaged and is leaking the enzyme. The damage could have been physical, such as a car accident, or chemical, such as a poison that killed part of the liver, releasing the enzyme.

How high the number goes can, but doesn’t always, tell us how bad the damage is, and a very high number doesn’t necessarily mean that the situation is hopeless.

Likewise, a low ALT doesn’t mean that everything in the liver is rosy. Remember, we said that none of these tests tell us how well the liver is functioning.

A classic example is that of a patient with cirrhosis of the liver, or a liver which has been poorly supplied with blood circulation for a long time. These are examples of livers which will function poorly but which have ALT levels that will likely be normal, because the liver isn’t leaking the enzyme.

Are you starting to understand why it’s not always clear-cut when the doctor can’t tell you exactly what’s wrong, even though he’s run a lot of tests?

Other test results in a broad-based chemistry panel that will tell us about the liver include SGOT, alkaline phosphatase (SAP) and bilirubin. Unfortunately, there isn’t space to go into detail about each of these.

Dr. Jim Randolph is a veterinarian at Animal General Hospital in Long Beach, Miss.