IRIS Staging of CKD

IRIS Stages

IRIS Stage Creatinine SDMA Comments
At Risk <1.4 mg/dL (dog)
<1.6 mg/dL (cat)		 <14 μg/dL Clinical history may suggest increased risk for CKD development
Stage 1 <1.4 mg/dL (dog)
<1.6 mg/dL (cat)		 <14 μg/dL Nonazotemic. Some other renal abnormality present
Stage 2 1.4-2.0 mg/dL (dog)
1.6-2.8 mg/dL (cat)		 14-25 μg/dL Mild renal azotemia. Clinical signs usually mild or absent.
Stage 3 2.1-5.0 mg/dL (dog)
2.9-5.0 mg/dL (cat)		 ≥25 μg/dL Moderate renal azotemia. Extrarenal clinical signs may be present.
Stage 4 >5.0 mg/dL (dog)
>5.0 mg/dL (cat)		 ≥45 μg/dL Severe renal azotemia

Substaging by Arterial Blood Pressure

Systolic BP mm Hg BP Substage Risk of Organ Damage*
<150 Normotensive Minimal
150-159 Borderline hypertensive Low
160-179 Hypertensive Moderate
≥180 Severely Hypertensive High

*Some breeds, particularly sight hounds, tend to have higher blood pressure than other breeds. It is preferable to use breed-specific reference ranges if available. The classification of risk of future target organ damage in “high-pressure breeds” might be adjusted as follows:

Minimal risk
systolic pressure <10 mm Hg above the breed-specific reference range
Low risk
systolic pressure 10-20 mm Hg above the breed-specific reference range
Moderate risk
systolic pressure 20-40 mm Hg above the breed-specific reference range
High risk
systolic pressure >40 mm Hg above the breed-specific reference range.

Substaging by Proteinuria

UP/C Value Substage
Dogs <0.2
Cats <0.2		 Non-proteinuric
Dogs 0.2 to 0.5
Cats 0.2 to 0.4		 Borderline proteinuric
Dogs >0.5
Cats >0.4		 Proteinuric