An elevated SDMA level in your cat signals that the kidneys aren’t filtering as efficiently as they should, but the number itself isn’t something you treat directly. Lowering SDMA means addressing the underlying cause of reduced kidney function, whether that’s chronic kidney disease, dehydration, hyperthyroidism, or exposure to something toxic. The good news is that several proven strategies can slow kidney decline, and in some cases, SDMA levels do come back down.
What SDMA Actually Tells You
SDMA (symmetric dimethylarginine) is a waste product that the kidneys filter out of the blood. When kidney filtration drops, SDMA builds up. The International Renal Interest Society uses SDMA alongside creatinine to stage chronic kidney disease (CKD) in cats:
- Stage 1: SDMA below 18 µg/dL
- Stage 2: SDMA 18 to 25 µg/dL
- Stage 3: SDMA 26 to 38 µg/dL
- Stage 4: SDMA above 38 µg/dL
SDMA can detect kidney problems earlier than creatinine in some cats. One study found that an SDMA of 14 µg/dL corresponded to roughly a 24% drop in kidney filtration. However, a cutoff that low also produces false positives about 25% of the time, which is why the threshold was raised to 18 µg/dL. If your cat’s SDMA is only mildly elevated, it’s worth retesting before assuming the worst.
Rule Out Non-Kidney Causes First
Not every elevated SDMA means permanent kidney damage. Research on hyperthyroid cats shows that thyroid hormone status independently raises SDMA, regardless of how well the kidneys are actually working. Cats with untreated hyperthyroidism tend to have higher SDMA than cats with normal thyroid levels. If your cat hasn’t had a thyroid panel, that’s an important piece of the puzzle, because treating the thyroid problem can bring SDMA back down on its own.
Dehydration is another common culprit. A cat that isn’t drinking enough or has been vomiting will temporarily concentrate waste products in the blood, pushing SDMA higher. Acute kidney injuries from NSAID exposure, urinary tract obstructions, infections like pyelonephritis, or even a recent general anesthesia event can also spike SDMA. These causes are often reversible once the underlying problem is treated.
Switch to a Kidney-Supportive Diet
Dietary change is the single most evidence-backed intervention for cats with CKD. According to Cornell University’s College of Veterinary Medicine, therapeutic kidney diets that restrict protein, phosphorus, and sodium while increasing water-soluble vitamins, fiber, and antioxidants can both prolong life and improve quality of life.
These diets work by reducing the waste products the kidneys have to process. Less dietary protein means less nitrogen waste. Lower phosphorus slows the cascade of damage that happens when the kidneys can no longer clear phosphate efficiently. Commercial prescription kidney diets from brands your vet carries are specifically formulated to hit these targets. Transitioning gradually over one to two weeks helps your cat accept the new food, since many cats are picky about changes.
For cats in early-stage CKD, phosphorus management may be especially important. Research shows that a hormone called FGF-23 rises in cats with elevated SDMA even before blood phosphorus levels look abnormal on standard tests. Your vet may recommend measuring FGF-23 to decide whether phosphorus restriction should start sooner rather than later.
Keep Your Cat Well Hydrated
Kidneys that are already struggling perform worse when dehydrated. Encouraging water intake is one of the simplest things you can do at home. Wet food is a practical first step since it’s roughly 70 to 80% water, compared to about 10% in dry kibble. Water fountains, multiple water bowls in different rooms, and adding a small amount of warm water or low-sodium broth to food can also help.
For cats with more advanced CKD who can’t stay hydrated on their own, veterinarians often prescribe subcutaneous fluids given at home. The International Society of Feline Medicine recommends this approach for managing dehydration in CKD cats. Owners who give subcutaneous fluids typically report that their cats show fewer symptoms and have fewer complications like constipation. Your vet will show you the technique, and most cats tolerate it well once you both get used to the routine.
Medications That Protect the Kidneys
When CKD causes protein to leak into the urine (proteinuria), your vet may prescribe medication to reduce the pressure inside the kidneys’ tiny filtering units. Two main types of drugs do this by blocking a hormone system called the RAAS, which the body ramps up during kidney disease. That system raises pressure inside the kidneys to maintain filtration in the short term, but over time it damages the filters and drives inflammation and scarring.
Telmisartan, an angiotensin receptor blocker, is commonly used in cats for this purpose. It blocks the damaging effects of the hormone angiotensin-II at the receptor level and has additional protective properties through a secondary pathway that other drugs in its class don’t share. Benazepril, an ACE inhibitor, works by reducing production of that same hormone. Both are given once daily by mouth. Your vet will choose based on your cat’s specific situation, and periodic bloodwork and urine tests help track whether the medication is working.
These medications don’t directly lower SDMA, but by protecting the kidneys from further damage, they help preserve the filtration capacity that determines where SDMA ends up.
Omega-3 Fatty Acids
Fish oil supplements rich in DHA and EPA may offer some kidney protection. Research in cats with early CKD has tested DHA-enriched fish oil at doses of 250 to 500 mg per kilogram of body weight daily, with the goal of reducing proteinuria and inflammation. The minimum daily requirement for combined DHA and EPA in adult cats is only 1.6 mg/kg, so therapeutic doses for kidney support are significantly higher than what a cat would get from regular food.
If you want to add fish oil, work with your vet on the right dose. Too much can cause digestive upset or interfere with blood clotting, and not all fish oil products are appropriate for cats. A veterinary-specific supplement is the safest option.
Remove Kidney-Damaging Exposures
Some of the most dramatic SDMA spikes come from toxic exposures that cause acute kidney injury. Lilies are the most dangerous household plant for cats. Every part of the plant, including the pollen and water in the vase, can cause fatal kidney failure. NSAIDs like ibuprofen and naproxen are another common cause of kidney damage in cats, and even veterinary NSAIDs can occasionally cause problems. If your cat’s SDMA rose suddenly, think about whether anything new entered the environment: a bouquet of flowers, a dropped pill, access to antifreeze, or a recent medication change.
For cats already diagnosed with CKD, avoiding further insults to the kidneys matters even more. That means being cautious with any medications that require kidney clearance and keeping your cat away from known toxins.
Monitoring Over Time
SDMA is most useful as a trend rather than a single snapshot. One elevated reading could reflect dehydration, a lab quirk, or a temporary illness. Repeated measurements over weeks or months tell you whether kidney function is stable, declining, or actually improving with treatment. Your vet will likely recheck SDMA alongside creatinine, urine protein levels, and phosphorus at regular intervals.
In early-stage disease, rechecks every three to six months are typical. In more advanced stages, every one to three months gives a clearer picture. If your cat’s SDMA was elevated but other kidney values looked normal, a retest in a few weeks can help clarify whether you’re dealing with true kidney disease or a temporary bump. Cats with mildly elevated SDMA and no other abnormalities sometimes retest within normal range, especially once hydration and diet are optimized.