Published by: Ingrid King. Last Updated on: February 1, 2023 by Crystal Uys
This post is sponsored by IDEXX Laboratories
Chronic Kidney Disease, also known as Chronic Renal Failure (CRF) is a common condition in aging cats. It is the result of a gradual decrease in kidney function. Healthy kidneys act like a filter to remove waste products from the body. They regulate electrolytes such as potassium and phosphorous, and they produce erythropoietin which stimulates red blood cell production. Kidneys produce rennin, which contributes toward regulating blood pressure. Kidneys also play a major role in turning vitamin D into its active form, which controls calcium balance in the body.
When kidney function becomes compromised, cats may not even show symptoms at first. However, the disease is progressive and damage is irreversible, which is why early diagnosis and intervention is so important.
New biomarker provides early warning
SDMA, short for symmetric dimethylarginine, is a new biomarker for kidney function. Since SDMA is almost exclusively eliminated by renal filtration, it is a good estimate of glomerular filtration rate (GFR), an indicator of how well the kidneys are working.
Currently, kidney disease is diagnosed by testing blood levels of creatinine and BUN, and by urinalysis. However, since creatinine levels are dependent on lean body mass, an underweight cat in renal failure may have normal blood creatinine levels, so the diagnosis of kidney failure could be missed if only a blood chemistry is run. SDMA is not influenced by muscle mass.
Earlier detection allows for better treatment success
Travis Pond, DVM, the owner of American Pet Hospital in Las Vegas, NV, was part of a field trial of the new test. “We used the test on about 100 cats over a period of two to three months,” said Dr. Pond. They found elevated SDMA levels in a few older cats that were not showing any symptoms of kidney disease, but a more common scenario was that the blood chemistry came back with borderline values. “These were the cases where we would be scratching our heads, wondering whether this was real kidney failure, or whether the cat was just dehydrated at the time the blood was drawn,” said Dr. Pond. “The SDMA marker helped clarify the other values.”
Dr. Pond’s clients have been very receptive to the new test. “I was impressed with how educated my clients were,” said Pond. “They knew about kidney disease, and they understood how important it was to diagnose it early.”
Earlier detection will lead to more successful treatment via medical and dietary means. Medical intervention can include increasing hydration by eliminating dry food, providing plenty of fresh water, and using supplements or medications that protect kidney function.
Diet changes may include phosphorus and sodium restriction. Many vets still recommend so-called prescription diets with restricted protein, but the studies that have evaluated the effect of reduced protein diets did not evaluate long term effects on the whole cat. Protein restriction causes muscle wasting, which is associated with decreased longevity and quality of life. Cats will actually use amino acids in their own muscle if inadequate protein is fed. There may be some benefit to reducing protein in the late stages of kidney disease.
Ask your vet about the SDMA test
Be sure to ask your vet about this test the next time you take your cat in for her check up. Dr. Pond recommends the SDMA test for cats as young as five years old, as kidney changes can start at that age. The test should definitely be included in preventive diagnostics for cats age six or older.
For more information about the SDMA test, please visit the IDEXX Laboratories website.
FTC Disclosure: This post is sponsored by IDEXX Laboratories, which means that I was compensated to feature this content. Regardless of payment received, you will only see products and information featured on this site that I believe will be of interest to you.
Ingrid King is an award-winning author, former veterinary hospital manager, and veterinary journalist who is passionate about cats.