IRIS CKD Staging Calculator for Dogs and Cats
Stage chronic kidney disease in dogs and cats by serum creatinine, with optional SDMA for Stage 1 detection. Returns the IRIS stage with the clinical management focus for each level.
Species
Serum creatinine (mg/dL)
Must be stable, hydrated. Repeat in 2 wks to confirm.
SDMA (μg/dL) — optional
Useful for IRIS Stage 1 (non-azotaemic CKD).
How to use this tool
IRIS staging thresholds (creatinine mg/dL)
Dogs: Stage 1: < 1.4 (with other evidence of CKD). Stage 2: 1.4-2.0. Stage 3: 2.1-5.0. Stage 4: > 5.0.
Cats: Stage 1: < 1.6. Stage 2: 1.6-2.8. Stage 3: 2.9-5.0. Stage 4: > 5.0.
Why SDMA matters
SDMA (Symmetric Dimethylarginine) rises earlier than creatinine when GFR declines - sometimes 18+ months earlier. A persistently elevated SDMA (> 14 μg/dL) with normal creatinine is a strong signal for early Stage 1 CKD and warrants further investigation (USG, UPC, blood pressure, imaging).
Sub-staging is essential
The bare stage number isn\'t the full diagnosis. IRIS recommends sub-staging by:
- Proteinuria (UPC): non-proteinuric (< 0.2), borderline (0.2-0.5 dog, 0.2-0.4 cat), proteinuric (above).
- Blood pressure: normotensive, low (≤ 150 mmHg), mild (150-159), moderate (160-179), severe (≥ 180) hypertensive risk.
Common Stage 2 management
Renal diet (controlled phosphorus and protein, omega-3 supplementation), regular monitoring (UPC, blood pressure, electrolytes q3-6 months), address hyperphosphataemia with binders if needed, treat hypertension if present.
Frequently asked questions
What are the IRIS creatinine cutoffs for CKD staging?
Dogs: Stage 2 starts at 1.4 mg/dL, Stage 3 at 2.1, Stage 4 at > 5.0. Cats: Stage 2 starts at 1.6, Stage 3 at 2.9, Stage 4 at > 5.0. Stage 1 is non-azotaemic - normal creatinine but other CKD evidence (elevated SDMA, low USG, structural changes).
What does SDMA add to IRIS staging?
SDMA rises with declining GFR earlier than creatinine - sometimes 18+ months earlier. A persistently elevated SDMA (> 14 μg/dL) with normal creatinine is a strong signal for early Stage 1 CKD.
Is the IRIS stage the complete diagnosis?
No. IRIS recommends sub-staging by proteinuria (UPC ratio) and blood pressure for the full diagnosis. Full format: "IRIS Stage 2, proteinuric, mild hypertensive risk".