SDMA in Cats: Early Kidney Disease Detection Guide
SDMA (Symmetric Dimethylarginine) is an early marker of kidney function that detects disease when only 25% of kidney function is lost—long before creatinine rises. Normal range: 0-14 µg/dL.
If your cat's bloodwork shows an elevated SDMA value, it's one of the earliest warning signs of kidney disease. SDMA is more sensitive than traditional markers like creatinine, making it crucial for catching chronic kidney disease (CKD) early when treatment is most effective.
What Is SDMA?
SDMA (Symmetric Dimethylarginine) is a biomarker produced during protein breakdown in the body. Unlike creatinine, which is affected by muscle mass and diet, SDMA levels correlate directly with kidney function and nothing else.
Why SDMA is Revolutionary:
- Early Detection: Rises when only 25-40% of kidney function is lost (vs 75% for creatinine)
- Unaffected by Muscle Mass: Reliable in thin, elderly, or sick cats
- Diet-Independent: Not influenced by protein intake
- Consistent Across Labs: Standardized testing methodology
Normal SDMA Ranges for Cats
- 0-14 µg/dL: Normal kidney function
- 15-17 µg/dL: Borderline (recheck in 2-4 weeks)
- 18-25 µg/dL: Mild kidney disease (IRIS Stage 2)
- 26-38 µg/dL: Moderate kidney disease (IRIS Stage 3)
- 39+ µg/dL: Severe kidney disease (IRIS Stage 4)
Note: SDMA should always be interpreted alongside creatinine, BUN, and urine specific gravity for the most accurate assessment.
SDMA vs Creatinine: The Key Difference
SDMA
- ✓ Detects disease at 25-40% kidney loss
- ✓ Not affected by muscle mass
- ✓ Independent of diet
- ✓ More sensitive early marker
- ✓ Ideal for thin/senior cats
Creatinine
- • Detects disease at 75% kidney loss
- • Influenced by muscle mass
- • Can vary with diet
- • Traditional marker
- • Less reliable in wasted cats
Real-World Example: A 15-year-old cat with muscle loss may have "normal" creatinine (1.8 mg/dL) but elevated SDMA (20 µg/dL), revealing early kidney disease that creatinine missed.
Not sure if your cat's SDMA is concerning or just borderline?
Upload your cat's bloodwork to VetLens for instant analysis comparing SDMA with creatinine, BUN, and clinical context.
Analyze Bloodwork NowWhat Causes High SDMA in Cats?
- Chronic Kidney Disease (CKD): Most common cause, especially in cats over 7 years old
- Acute Kidney Injury: Toxins (lilies, antifreeze), infections, or urinary blockage
- Dehydration: Can mildly elevate SDMA, but less than creatinine
- Hyperthyroidism: Can mask kidney disease; SDMA reveals true kidney function
Important Note:
Unlike creatinine, SDMA rarely gives false positives. If SDMA is elevated, there's almost always reduced kidney function—even if creatinine is still normal.
What to Do If Your Cat's SDMA Is Elevated
Step 1: Retest (for borderline values 15-17)
A single borderline value may be temporary. Recheck in 2-4 weeks along with:
- • Complete kidney panel (creatinine, BUN, phosphorus)
- • Urinalysis with specific gravity
- • Blood pressure check
Step 2: Stage the Disease (if confirmed elevated)
Your vet will use the IRIS (International Renal Interest Society) staging system:
- • Stage 1: SDMA 15-17, creatinine normal (early intervention)
- • Stage 2: SDMA 18-25, mild symptoms (diet changes, monitoring)
- • Stage 3: SDMA 26-38, moderate symptoms (medications, fluids)
- • Stage 4: SDMA 39+, severe symptoms (intensive management)
Step 3: Begin Management
- Kidney Diet: Lower protein and phosphorus (Hill's k/d, Royal Canin Renal)
- Hydration: Wet food, water fountains, subcutaneous fluids if needed
- Phosphorus Binders: If phosphorus is elevated
- Blood Pressure Control: ACE inhibitors if hypertensive
- Regular Monitoring: Recheck SDMA every 3-6 months
Can SDMA Go Back to Normal?
In some cases, yes—especially if the elevation was due to:
- • Dehydration: SDMA may normalize after rehydration
- • Acute kidney injury: If caught early and reversible (e.g., urinary blockage)
- • Hyperthyroidism treatment: Treating hyperthyroidism may reveal stable kidney disease without worsening
However, chronic kidney disease is progressive and irreversible. Once SDMA is persistently elevated from CKD, the goal is to slow progression, not reverse it.
When to Worry About SDMA
Contact your vet immediately if:
- • SDMA is above 25 µg/dL
- • Your cat is vomiting, lethargic, or not eating
- • SDMA has doubled since the last test
- • Your cat is drinking excessively or urinating outside the litter box
Get Your Cat's SDMA Explained in Plain English
Upload your cat's bloodwork into VetLens and get:
- ✓ SDMA interpretation with CKD staging
- ✓ Comparison with creatinine and BUN
- ✓ Personalized diet and treatment recommendations
- ✓ Questions to ask your vet at your next visit
Frequently Asked Questions
What is a normal SDMA level for cats?
Normal SDMA levels in cats range from 0-14 µg/dL. Values of 15-17 are borderline and warrant monitoring. Values 18 or higher indicate reduced kidney function and possible chronic kidney disease.
Why is SDMA better than creatinine for detecting kidney disease?
SDMA detects kidney disease when only 25-40% of kidney function is lost, while creatinine typically doesn't rise until 75% of function is gone. SDMA is also unaffected by muscle mass, making it more reliable in thin or senior cats.
What causes high SDMA in cats?
Elevated SDMA primarily indicates reduced kidney function from chronic kidney disease, acute kidney injury, or early-stage kidney damage. Unlike creatinine, SDMA is less affected by dehydration or diet, making it a more specific marker of kidney health.
Should I retest if SDMA is borderline (15-17)?
Yes. Borderline SDMA values should be retested in 2-4 weeks along with creatinine, BUN, and urinalysis. If it remains elevated or increases, your vet may diagnose early-stage CKD and recommend dietary changes and increased monitoring.