Diagnosing, Staging, and Treating Chronic Kidney Disease in Dogs and Cats
Chronic kidney disease (CKD) is diagnosed based on evaluation of all available clinical and diagnostic information in a stable patient. Following diagnosis of CKD, the IRIS Board recommends using serum creatinine or SDMA (ideally both) to stage CKD with substaging based on assessment of arterial blood pressure and proteinuria. Step 1: Diagnose CKD Clinical signs and physical Clinical presentation Physical examination findings examination findings worsen Consider age, sex, breed predispositions, and relevant Can be normal in early stage CKD. Findings historical information, including medication history, may include palpable kidney abnormalities, with increasing severity of toxin/toxicant exposure, and diet. evidence of weight loss, dehydration, kidney disease Can be subclinical in early stage CKD. Signs may include pale mucous membranes, uremic ulcers, polyuria, polydipsia, weight loss, decreased appetite, evidence of hypertension, i.e., retinal lethargy, dehydration, vomiting, and bad breath. hemorrhages/detachment.
To diagnose Stage 1 and early Stage 2 CKD OR To diagnose more advanced CKD (late Stage 2–4) One or more of these diagnostic findings: Both of these diagnostic findings:
1 Creatinine S M ncreased creatinine and S M concentrations 1
Creatinine SDMA Creatinine increasing within the increasing within the reference interval where no reference interval where no S M re erence interval reference interval prerenal cause is apparent prerenal cause is apparent
Jun ’11 Jun ’12 Jun ’13 June July Aug Sept Results of both tests should be interpreted in light of patient’s hydration status. 2 Persistent increased SDMA* >14 µg/dL 3 Abnormal kidney imaging plus Urine Urine specific gravity specific gravity 2 <1.030 <1.035†
4 Persistent renal proteinuria UPC >0.5 in dogs; UPC >0.4 in cats
0.6 0.7 1.0 1.030 Canine 1.008 Sept ’15 Oct ’15 Nov ’15 Urine protein to creatinine (UPC) ratio 1.035 Feline 1.008
See www.iris-kidney.com for more detailed staging, †Note that some cats can produce hypersthenuric therapeutic, and management guidelines. urine in the face of renal azotemia. Step 2: Stage CKD
Stage 1 Stage 2 Stage 3 Stage 4 No azotemia Mild azotemia Moderate azotemia Severe azotemia (Normal creatinine) (Normal or mildly elevated creatinine)
Creatinine in mg/dL Less than Greater than 1.4–2.8 2.9–5.0 5.0 1.4 µ µ Stage Canine (125 µmol/L) (125–250 mol/L) (251–440 mol/L) (440 µmol/L) based on stable creatinine Less than Greater than Feline 1.6–2.8 2.9–5.0 5.0 1.6 µ µ (140 µmol/L) (140–250 mol/L) (251–440 mol/L) (440 µmol/L)
SDMA* in µg/dL Less than Greater than Canine 18–35 36–54 Stage 18 54 based on stable SDMA Less than Greater than Feline 18 18–25 26–38 38 UPC ratio Substage Canine Nonproteinuric <0.2 Borderline proteinuric 0.2–0.5 Proteinuric >0.5 based on proteinuria Feline Nonproteinuric <0.2 Borderline proteinuric 0.2–0.4 Proteinuric >0.4 Systolic blood pressure in mm Hg Normotensive <140 Prehypertensive 140–159 Substage based on Hypertensive 160–179 Severely hypertensive >_180 blood pressure
Note: In the case of staging discrepancy between creatinine *SDMA = IDEXX SDMA® Test See www.iris-kidney.com for more and SDMA, consider patient muscle mass and retesting detailed staging, therapeutic, and both in 2–4 weeks. If values are persistently discordant, management guidelines. consider assigning the patient to the higher stage. Step 3: Treat CKD
Stage 1 Stage 2 Stage 3 Stage 4
Treatment Use nephrotoxic drugs Same as Stage 1 Same as Stage 2 Same as Stage 3 with caution recommendations Renal therapeutic diet Keep phosphorus Keep phosphorus Correct prerenal and <5.0 mg/dL <6.0 mg/dL Treat hypokalemia in cats postrenal abnormalities (<1.6 mmol/L) (<1.9 mmol/L) Fresh water available at Treat metabolic acidosis Consider feeding tube for all times nutritional and hydration Consider treatment support and ease of Monitor trends in creatinine of anemia medicating and SDMA to document Treat vomiting, stability or progression inappetence, and nausea Investigate for and treat Increased enteral or underlying disease and/or subcutaneous fluids may complications be required to maintain Treat hypertension if systolic hydration blood pressure persistently Consider calcitriol therapy >160 or evidence of in dogs end-organ damage Treat persistent proteinuria with renal therapeutic diet and medication (UPC >0.5 in dogs; UPC >0.4 in cats) Keep phosphorus <4.6 mg/dL (<1.5 mmol/L) If required, use renal therapeutic diet plus phosphate binder
See www.iris-kidney.com for more detailed staging, therapeutic, and management guidelines.