IRIS Stage 3 CKD in dogs is characterized by a creatinine level between _____.

• A. 1.0-2.0 mg/dL
• B. 2.9-5.0 mg/dL
• C. 5.0-6.0 mg/dL
• D. 0.5-0.9 mg/dL

Answer: (B)

Kidney function in IRIS CKD staging is gauged mainly by serum creatinine: higher creatinine means lower glomerular filtration rate. Stage 3 in dogs represents a moderate to severe decline in function, which is reflected by a creatinine level typically in the 2.9 to 5.0 mg/dL range. This places Stage 3 between the milder reductions seen in Stage 2 (roughly around 1.4–2.8 mg/dL) and the more advanced disease of Stage 4 (creatinine above 5.0 mg/dL). The other ranges correspond to either normal or near-normal function, or to milder or more severe disease, so they don’t fit Stage 3. Keep in mind that creatinine can be influenced by muscle mass and hydration, so veterinarians often confirm staging with repeat measurements and consider additional kidney indicators alongside the creatinine value.