Interpreting SDMA and Creatinine Kidney Values

KidneyQ&AMeongsiljang Veterinary Advisory Board

SDMA and creatinine are key blood markers for assessing kidney function in pets. We’ll explain what each value means, their normal ranges, and how to respond if abnormal results appear—all in clear, easy-to-understand terms for pet owners.

What’s the Difference Between SDMA and Creatinine?

Illustration comparing SDMA and creatinine blood tests

SDMA (symmetric dimethylarginine) and creatinine are two key blood markers used to assess kidney function in pets. The most important thing to remember is that these two values should always be evaluated together. SDMA levels begin to rise when kidney function is impaired by approximately 40%, whereas creatinine levels typically do not show a noticeable increase until kidney damage exceeds 75%. Therefore, it is helpful to think of SDMA as an "early warning signal" and creatinine as a "confirmatory indicator."

Why Should Both Values Be Evaluated Together?

Because creatinine is produced in muscle, pets with low muscle mass—such as underweight animals or senior dogs and cats—may show deceptively low creatinine levels even when their kidneys are compromised. In contrast, SDMA levels are largely independent of muscle mass, allowing for earlier detection of kidney disease in pets with reduced muscle. To avoid misinterpretation, SDMA should not be evaluated in isolation; instead, it should be interpreted alongside creatinine, BUN, and urine specific gravity as a comprehensive panel.

SDMA vs. Creatinine: A Quick Comparison

Item	SDMA	Creatinine
Point of detecting kidney damage	At about 40% damage	At about 75% damage
Muscle mass influence	Almost none	Greatly affected
Normal range (dog/cat)	0–14 µg/dL	Dog 0.5–1.4 / Cat 1.0–2.4 mg/dL
Utility for early diagnosis	High	Low
Included in IRIS staging criteria	Adjunct indicator	Primary indicator

Normal ranges and cutoff criteria may vary by testing laboratory and analyzer, and values near the reference limits require more caution in interpretation. Please check the reference range printed on your result sheet first.

What Does It Mean If the Values Are High?

If these values exceed the reference range, it means the kidneys are not filtering waste products from the blood effectively. Check for the following signs as well.

Elevated SDMA only: May indicate early chronic kidney disease or the initial stage of dehydration or acute injury.

Elevated creatinine only: May indicate muscle damage, recent high-protein diet, or transient dehydration.

Elevated SDMA and creatinine: May indicate moderate or worse decline in kidney function, possibly progressing to IRIS stages 2–4.

Low urine specific gravity as well: Indicates the kidneys have also lost their concentrating ability, requiring immediate consultation with a veterinarian.

A veterinarian explaining blood test results to a cat on the examination table.

Criteria for Immediate Veterinary Visit

If any of the following signs appear, please bring your pet to the clinic the same day rather than waiting. - SDMA levels are consistently rising or significantly above the reference range (typically 14 µg/dL) - Creatinine levels are more than twice the upper limit of the reference range - Water consumption is more than double the usual amount, or urine output has suddenly increased - Vomiting, decreased appetite, or weight loss persist for more than one week - Your cat is using the litter box frequently, but the urine clumps are unusually large Kidney disease in cats often progresses silently. If any of these signs are present, prompt re-evaluation is the safest course of action.

Interpreting Values Based on IRIS Stages

The International Renal Interest Society (IRIS) guidelines primarily use creatinine levels, with SDMA serving as a supplementary indicator.

Stage 1: Creatinine is within the normal range, but SDMA remains above 14, or other renal abnormalities such as decreased concentrating ability are present → Begin early management.

Stage 2: Mild elevation in creatinine (dogs: 1.4–2.0 mg/dL; cats: 1.6–2.8 mg/dL) → Implement comprehensive dietary management.

Stage 3: Moderate elevation in creatinine (dogs: 2.1–5.0 mg/dL; cats: 2.9–5.0 mg/dL) → Combine medication and fluid therapy.

Stage 4: Creatinine exceeds 5.0 mg/dL → Intensive treatment phase.

However, these values can vary depending on the testing laboratory and analytical methods, so they should not be viewed as definitive cutoffs. Clinical signs and urine specific gravity must be evaluated alongside the numerical results.

Checklist When Values Are Slightly Elevated

If a value is only slightly above the reference range, further evaluation is needed to determine whether it indicates true kidney disease or is merely a temporary fluctuation.

Check for dehydration: Assess skin turgor and gum moisture.

Blood draw timing: Blood drawn within two hours of a high-protein meal can cause a temporary rise in creatinine.

Non-renal causes: Factors that affect renal blood flow, such as severe dehydration or cardiovascular abnormalities, can also temporarily elevate SDMA levels.

Retest timing: Repeat the test in 2–4 weeks under the same conditions (fasting and calm).

Urinalysis: For accurate assessment, urine specific gravity and urine protein levels should also be evaluated.

Veterinary textbooks do not recommend diagnosing kidney disease based on a single elevated result alone.

Senior dogs drinking clean water and eating kidney-supportive meals

Don’t Let Your Guard Down Even If Values Are Normal

Even if SDMA and creatinine levels fall within the normal range, an inability to maintain appropriate urine specific gravity may indicate impaired renal concentrating ability. In fact, SDMA can rise before the kidneys lose their ability to concentrate urine, so rather than assuming everything is fine based on normal values alone, it’s important to also evaluate urine specific gravity. The appropriate reference range for urine specific gravity differs between dogs and cats, and reference intervals may vary depending on the laboratory. Therefore, always refer to the reference ranges provided on the test report and consider your veterinarian’s clinical judgment. For senior pets aged seven years and older, the most reliable preventive measure is to regularly monitor both kidney values and urinalysis results together.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

My dog’s SDMA level is 15, but the creatinine is normal. Is that okay?

Early kidney dysfunction may be suspected. Recheck SDMA, creatinine, and urine specific gravity together after 2–4 weeks while fasting; if levels remain consistently elevated, consult your veterinarian about dietary management.

Is fasting required before blood collection?

Yes, we generally recommend fasting for 8 to 12 hours. Since creatinine and BUN levels can temporarily rise after eating, a fasting state is best for obtaining accurate results. However, your pet can drink water freely.

My cat is on the lean side, and their creatinine level came back low. Is this something to worry about?

Low muscle mass can lead to low creatinine levels, so it’s hard to feel reassured based on creatinine alone. Be sure to check SDMA and urine specific gravity as well, since they are less affected by muscle mass.

Once kidney values rise, can they return to normal?

If the issue is acute dehydration or dietary factors, it can often be resolved with proper hydration and dietary adjustments. However, with chronic kidney disease, the damaged kidney tissue cannot be restored, so the goal shifts to "managing" the condition to prevent further deterioration of the values.

Do most general veterinary clinics offer SDMA testing?

Most tests are sent to external laboratories. Typically, blood is drawn at a local clinic and sent out for analysis, with results returning within one to three days. However, more clinics are now equipped with in-house analyzers, allowing for faster on-site testing.

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References

[1] Langston CE, Eatroff AE. Chronic Kidney Disease. Small Animal Critical Care Medicine, 3rd Edition

[2] The Cat, Clinical Medicine and Management, 2nd Edition - Urinary Tract Disease

[3] IRIS (International Renal Interest Society) Staging Guidelines 2023