Carsten column: The blood chemistry panel and your pet companion

Dr. Ron Carsten
The Integrative Pet Vet
Dr. Ron Carsten.

The blood-chemistry panel is an essential part of the health assessment for pet companions. It is used in conjunction with the complete blood count (CBC) to form a more complete picture of health status (see the Aug. 30 Glenwood Springs Post Independent article).

Unlike the CBC, which uses blood that has not clotted, the chemistry panel uses serum. Serum is the fluid that remains after clotting. The serum is removed from the clot before the blood-chemistry panel is performed. Removing the clot also prevents further changes resulting from ongoing contact with the blood cells.

It is important to remember that the CBC evaluates red blood cell (RBC), white blood cell (WBC), and platelet numbers and other blood-cell measures. This is in contrast to the chemistry profile that includes tests for organs like the kidneys and liver as well as basic tests like glucose, cholesterol and electrolytes like sodium, potassium, and calcium. Commonly available test profiles run from a handful of tests up to almost 30.

Beyond the basic chemistry profiles, an extensive list of specialized testing is available. Specialized testing would be requested based on the characteristics of the illness and the pattern of results from the CBC and the chemistry profile.

There are a number of situations where your veterinarian would recommend a chemistry panel (usually in conjunction with a CBC). These include when your pet is ill, when monitoring response to treatment or as part of a wellness evaluation or pre-surgery screening. Individual test results and patterns of results provide guidance for making a diagnosis or determining which drugs to use for anesthesia.

For example, it is recognized that kidney tests (like creatinine) are not abnormal until 2/3 to 3/4 of the kidney function is lost. The SDMA is a newer test that provides earlier indications than creatinine about potential kidney concerns. Adding to the challenge of interpreting kidney blood chemistry results, it is important to determine if the pattern of results indicates a problem preventing the kidney from functioning efficiently like low blood flow to the kidney, a primary kidney problem or something impeding the urine flow like kidney stones. Understanding where the problem is located or what is causing the change in test results related to the kidney is vital for formulating a treatment or support plan.

Another important consideration is determining if the kidney problem is acute or chronic. Pets with chronic kidney disease have the opportunity to adapt to the worsening kidney function, so they can withstand higher numbers for SDMA, creatinine, and BUN (blood urea nitrogen). However, the chronic change in kidney function can lead to elevated phosphorus, anemia and problems with blood pressure. Each of these patterns of results have impacts on how the pet is managed.

Blood chemistry results for liver tests can also be assessed for the pattern of values. Unlike the kidney tests, the typical liver tests don’t directly measure function. For example, the ALT is an enzyme released from liver cells as they die. Some amount of cell turnover (death) is normal. When liver cell turnover becomes excessive, the ALT will rise as long as the liver size is normal. On the other hand, liver tests like ALP provide information about the bile system. Complicating interpretation is that elevations in ALP don’t always mean liver. ALP can be induced to increase when there are increased steroids in the blood, either naturally occurring or given as a medication. Sometimes, it is important to perform additional tests like the bile acids panel to assess liver function.

Other common tests on the blood chemistry panel like the T4 and cholesterol may imply a low functioning thyroid in the dog. However, cholesterol can be elevated when the pet was not fasted prior to obtaining the blood sample. The T4 can be low due to the effect of diseases not directly involving the thyroid or certain medications. Untangling the thyroid results sometimes means performing additional tests like a thyroid panel that includes other tests in addition to the T4.

This brief discussion gives a glimpse of the power of the blood chemistry panel and how the different tests when interpreted together provide a broader understanding of the health of your pet companion. If you have concerns or questions about your companion’s health, contact your veterinarian. Perhaps a blood chemistry panel and CBC are indicated.

Ron Carsten, DVM, PhD, CVA, CCRT was one of the first veterinarians in Colorado to use the integrative approach, has lectured widely to veterinarians, and has been a pioneer in the therapeutic use of food concentrates to manage clinical problems. He is also the founder of Colorado Animal Rescue (CARE). In addition to his Doctor of Veterinary Medicine, he holds a PhD in Cell and Molecular Biology and is a Certified Veterinary Acupuncturist and Certified Canine Rehabilitation Therapist. He practices integrative veterinary medicine in Glenwood Springs.

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