What are the stages of chronic kidney disease (CKD) and their management strategies?

Chronic Kidney Disease Stages

Chronic kidney disease is classified into five stages based on glomerular filtration rate (GFR), with the diagnosis requiring either kidney damage or GFR < 60 mL/min/1.73 m² persisting for 3 or more months. 1

CKD Stage Definitions

Stage 1: Kidney Damage with Normal or Increased GFR

• GFR ≥ 90 mL/min/1.73 m² with evidence of kidney damage (albuminuria, proteinuria, hematuria, or imaging abnormalities) 1, 2
• Requires markers of kidney damage for diagnosis; GFR alone is insufficient 2
• Persistent proteinuria is the principal marker, with albumin-creatinine ratio > 30 mg/g considered abnormal 3

Stage 2: Mild GFR Reduction with Kidney Damage

• GFR 60-89 mL/min/1.73 m² with evidence of kidney damage 1, 2
• Like Stage 1, requires documented kidney damage markers for diagnosis 2

Stage 3: Moderate GFR Reduction

• Stage 3a: GFR 45-59 mL/min/1.73 m² 1
• Stage 3b: GFR 30-44 mL/min/1.73 m² 1
• Can be diagnosed based on GFR alone without additional markers of damage 2
• Represents loss of half or more of normal adult kidney function 3
• Risk of complications (hypertension, anemia, malnutrition, bone disease) increases significantly below GFR 60 mL/min/1.73 m² 3, 2

Stage 4: Severe GFR Reduction

• GFR 15-29 mL/min/1.73 m² 1, 2
• Hypertension prevalence approaches 80% at this stage 2
• Multiple complications become substantially more likely 2
• Mandatory nephrology referral and co-management required 1

Stage 5: Kidney Failure

• GFR < 15 mL/min/1.73 m² or dialysis 1, 2
• Kidney replacement therapy (dialysis or transplantation) indicated if uremic symptoms develop 1, 2

Critical Diagnostic Considerations

GFR Estimation

• Use prediction equations (MDRD, CKD-EPI) that account for serum creatinine, age, sex, and race rather than serum creatinine alone 2, 4
• Clinical laboratories do not report GFR estimates > 60 mL/min/1.73 m² as numeric values due to reduced accuracy at higher levels 3

Albuminuria Classification

• Albuminuria must be assessed alongside GFR for comprehensive risk stratification 1, 2
• Categories: A1 (normal to mildly increased), A2 (moderately increased), A3 (severely increased) 2
• The combination of GFR and albuminuria provides superior risk stratification for disease progression and outcomes 2

Duration Requirement

• Abnormalities must persist for at least 3 months for CKD diagnosis 3, 2, 5

Stage-Specific Management Priorities

Stages 1-2: Early Detection and Risk Reduction

• Focus on diagnosis and treatment of underlying conditions 1
• Slow progression through cardiovascular disease risk reduction 1
• Glycemic control (target HbA1c individualized) and blood pressure control (target < 130/80 mmHg) 6
• ACE inhibitors or ARBs for albuminuria ≥ 30 mg/g, especially in diabetic kidney disease 6

Stage 3: Evaluate and Treat Complications

• Estimate progression rate 2
• Begin evaluation for complications including anemia, bone and mineral disease, metabolic acidosis 1, 2
• Monitor hemoglobin and consider iron supplementation 6

Stage 4: Prepare for Kidney Replacement Therapy

• Intensive management of complications 2
• Preparation for possible dialysis or transplantation 1
• All patients require nephrology referral at this stage 1, 6

Stage 5: Kidney Replacement Therapy

• Initiate dialysis or pursue transplantation when uremia present 1

Critical Pitfalls to Avoid

• Do not dismiss age-related GFR decline as "normal aging"—decreased GFR in elderly patients remains an independent predictor of death and cardiovascular disease 3, 1
• Refer to nephrology no later than Stage 4 (GFR < 30 mL/min/1.73 m²) to avoid late referral complications 6, 7
• Avoid nephrotoxins including NSAIDs 5
• Adjust drug dosing for antibiotics and oral hypoglycemic agents based on GFR 3, 5
• Restrict routine testing to patients at increased risk (age > 60 years, hypertension, diabetes, cardiovascular disease, family history of CKD) to reduce false-positive results 3, 7