What is SDMA in cats?

What is SDMA in cats?

SDMA (symmetric dimethylarginine) is a kidney function marker measured in routine cat blood work. It's the earliest sign of declining kidney function, often rising 6 months or more before creatinine becomes elevated. Normal range: under 14 µg/dL. The IDEXX laboratory introduced SDMA to clinical practice in 2015; it's now standard on senior cat panels.

What does an SDMA value mean for my cat?

• Under 14 µg/dL: normal. No kidney concern at this snapshot.
• 14 to 18 µg/dL: mildly elevated. Monitor. Recheck in 2 to 4 weeks. Could indicate early kidney function decline OR a transient dehydration.
• Over 18 µg/dL: the lab flags kidney concern. Work-up indicated. May correspond to IRIS Stage 2 or higher CKD.

These are general reference ranges from the IRIS staging system (2023). Always interpret SDMA in context with creatinine, BUN, urine specific gravity, and clinical signs. Source: IRIS Staging Guidelines for Feline CKD.

Why does SDMA matter more than creatinine for early CKD detection?

Creatinine doesn't rise until approximately 75% of kidney function is already lost. By then, the disease has been progressing silently for months or years. SDMA is more sensitive: it begins rising at around 40% loss of kidney function, giving you a 6+ month window to intervene before creatinine catches up. Catching CKD at IRIS Stage 1 vs Stage 3 changes prognosis significantly.

How does Pawtient AI help with SDMA interpretation?

Snap a photo of your cat's lab report with the Pawtient AI lab value translator. The app reads the SDMA value, places it in IRIS staging context for your cat's age and weight, and generates a one-page summary for the vet visit, with the right questions to ask based on the value's trajectory.

What questions should I ask my vet about an elevated SDMA?

1. What is my cat's IRIS stage based on this SDMA + creatinine + USG?
2. How does this value compare to last test? Is the trajectory up, flat, or down?
3. What's the next milestone I should monitor at home (water intake, weight, appetite)?
4. When should we retest, and what would change treatment?
5. Is a prescription kidney diet appropriate at this stage?
6. What's the worst-case sign that means I should call you immediately?

Sources and further reading

• IRIS Staging Guidelines for Feline CKD (2023)
• AAHA Senior Care Lab Guidelines
• IDEXX SDMA reference materials

This page is educational content. It is not veterinary advice. Pawtient AI is an AI assistant and second opinion, never diagnosis. Always consult a licensed veterinarian for clinical decisions about your cat.