How do Vets Measure Kidney Disease?

Dr. Barchas, My question relates to chronic kidney failure. I have had a total of three cats with this, two now and one that passed...

Dr. Eric Barchas  |  May 2nd 2008


Dr. Barchas,

My question relates to chronic kidney failure. I have had a total of
three cats with this, two now and one
that passed away about four years ago.

I have always been uncertain exactly what the
BUN number means. What does it show to you, the
vet, and what role it has in diagnosis along with
the creatinine numbers. I understand they both show
the stage of where of the kidneys are but I would
really like to understand more about
their role.

Thank you very much – This will help me to
understand this disease a little better.

Karin
Phoenixville, PA

Sadly, many cat lovers have experience with feline kidney disease (also known as chronic renal failure). Kidney failure is the most common major medical problem in elderly cats. It is a leading cause of feline death.

Veterinarians test their patients’ kidneys in a variety of ways. Physical examinations, X-rays, ultrasound exams, and urine tests all provide important information. But the most commonly used benchmarks are two values that are measured in the blood: BUN (pronounced “bee-you-inn”) and creatinine.

To understand the meaning of BUN and creatinine, you must understand the function of the kidneys. In the course of normal metabolism, the body’s organs and tissues consume nutrients and produce waste products. These waste products are released into the blood. It is the job of the kidneys to remove these waste products from the blood and eliminate them as urine.

If the kidneys begin to fail, the waste products accumulate in the blood. Higher levels of waste products correlate with lower levels of kidney function.

BUN and creatinine are two such waste products. Their levels generally correspond to the overall levels of waste products in the blood. Measurements of BUN and creatinine therefore allow veterinarians to assess the status of the kidneys, as well as to monitor each patient’s response to treatment.