What are the guidelines for diagnosing and managing Chronic Kidney Disease (CKD)?

Guidelines for Diagnosing and Managing Chronic Kidney Disease (CKD)

Chronic Kidney Disease is defined as abnormalities of kidney structure or function present for >3 months, diagnosed by persistent eGFR <60 mL/min/1.73 m² and/or evidence of kidney damage (primarily albuminuria ≥30 mg/g). 1

Diagnostic Approach

Initial Testing

• Test all people at risk for CKD using both urine albumin measurement and assessment of glomerular filtration rate (GFR) 2
• Use serum creatinine (SCr) and an estimating equation for initial assessment of GFR 2
• In adults at risk for CKD, use creatinine-based estimated glomerular filtration rate (eGFRcr) 2
• If cystatin C is available, estimate GFR using the combination of creatinine and cystatin C (eGFRcr-cys) 2

Confirming CKD Diagnosis

• Following detection of elevated urinary albumin-to-creatinine ratio (ACR), hematuria, or low eGFR, repeat tests to confirm presence of CKD 2
• Do not assume chronicity based on a single abnormal level for eGFR and ACR, as findings could result from acute kidney injury (AKI) or acute kidney disease (AKD) 2

Establishing Chronicity (minimum 3 months)

Proof of chronicity can be established by:

• Review of past measurements/estimations of GFR 2
• Review of past measurements of albuminuria/proteinuria and urine microscopic examinations 2
• Imaging findings such as reduced kidney size and reduction in cortical thickness 2
• Kidney pathological findings such as fibrosis and atrophy 2
• Medical history, especially conditions known to cause or contribute to CKD 2
• Repeat measurements within and beyond the 3-month point 2

CKD Staging

GFR Categories

• G1: ≥90 mL/min/1.73 m² (normal or high)
• G2: 60-89 mL/min/1.73 m² (mildly decreased)
• G3a: 45-59 mL/min/1.73 m² (mildly to moderately decreased)
• G3b: 30-44 mL/min/1.73 m² (moderately to severely decreased)
• G4: 15-29 mL/min/1.73 m² (severely decreased)
• G5: <15 mL/min/1.73 m² (kidney failure) 1

Albuminuria Categories

• A1: <30 mg/g (normal to mildly increased)
• A2: 30-300 mg/g (moderately increased)
• A3: >300 mg/g (severely increased) 1

Evaluation of CKD Cause

• Establish the cause of CKD using clinical context, personal and family history, social and environmental factors, medications, physical examination, laboratory measures, imaging, and genetic and pathologic diagnosis 2
• Consider kidney biopsy as a diagnostic test to evaluate cause and guide treatment decisions when clinically appropriate 2
• Basic laboratory tests should include complete blood count, comprehensive metabolic panel, urinalysis with microscopy, and urine protein quantification 1, 3

Special Considerations in Testing

• Where more accurate GFR assessment will impact treatment decisions, measure GFR using plasma or urinary clearance of an exogenous filtration marker 2
• Consider using eGFRcr-cys in clinical situations when eGFRcr is less accurate and GFR affects clinical decision-making 2
• Interpretation of serum creatinine level requires consideration of dietary intake 2
• For albuminuria assessment, use urinary albumin-to-creatinine ratio (UACR) in a first-void spot urine specimen; if not possible, a random spot urine specimen is acceptable 4

Management Approach

• Consider initiation of treatments at first presentation of decreased GFR or elevated ACR if CKD is deemed likely due to presence of other clinical indicators 2
• Prioritize slowing CKD progression at early stages 2
• Management includes:
  • Blood pressure control (<140/90 mmHg) 5
  • Use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers for patients with albuminuria and hypertension 5
  • Hemoglobin A1c ≤7% for patients with diabetes 5
  • Correction of CKD-associated metabolic acidosis 5
  • Avoidance of nephrotoxins (e.g., NSAIDs) 3, 5

Referral to Nephrology

• Refer patients to nephrology for:
  • eGFR <30 mL/min/1.73 m² 1, 5
  • Significant proteinuria/albuminuria 1, 5
  • Rapid decline in kidney function 1, 5
  • Difficulty determining the cause of CKD 1, 5
  • Complex management issues 1, 5

Common Pitfalls to Avoid

• Relying on a single abnormal test result to diagnose CKD 2
• Failing to test both eGFR and albuminuria in at-risk patients 2
• Not considering factors that can affect creatinine levels independent of kidney function (muscle mass, diet) 2
• Delaying referral to nephrology for advanced CKD 1, 6
• Not adjusting medication dosages based on kidney function 3, 5