Chronic Kidney Disease Stages and Management
Chronic kidney disease (CKD) is classified into five stages based on glomerular filtration rate (GFR) and evidence of kidney damage, with specific management strategies required for each stage to reduce morbidity and mortality. 1, 2
Definition of CKD
CKD is defined as either:
- Kidney damage persisting for ≥3 months, with or without decreased GFR, manifested by pathological abnormalities or markers of kidney damage (abnormalities in blood/urine composition or imaging tests)
- GFR <60 mL/min/1.73 m² persisting for ≥3 months, with or without evidence of kidney damage 1, 2
CKD Staging System
| Stage | GFR (mL/min/1.73 m²) | Description | Clinical Focus |
|---|---|---|---|
| 1 | ≥90 | Normal or elevated GFR with evidence of kidney damage | Diagnosis, risk reduction, treating comorbidities |
| 2 | 60-89 | Mildly decreased GFR with evidence of kidney damage | Slowing progression, CVD risk reduction |
| 3 | 30-59 | Moderately decreased GFR | Evaluating complications, estimating progression |
| 4 | 15-29 | Severely decreased GFR | Managing complications, preparing for replacement therapy |
| 5 | <15 or dialysis | Kidney failure | Replacement therapy if uremia present |
Note: Stages 1 and 2 require evidence of kidney damage (e.g., albuminuria, structural abnormalities), while stages 3-5 are defined by GFR alone. 1, 2
Albuminuria Classification
Albuminuria is an important marker of kidney damage and risk stratification:
| Category | Albumin-to-Creatinine Ratio (mg/g) | Description |
|---|---|---|
| A1 | <30 | Normal to mildly increased |
| A2 | 30-300 | Moderately increased |
| A3 | >300 | Severely increased |
Modern CKD classification incorporates both GFR stages (G1-G5) and albuminuria categories (A1-A3) for comprehensive risk assessment. 1, 2
Stage-Specific Management Strategies
Stage 1 (GFR ≥90 mL/min/1.73 m² with evidence of kidney damage)
- Diagnose underlying cause of kidney damage
- Implement CKD risk reduction strategies
- Treat comorbid conditions
- Blood pressure control (target <130/80 mmHg)
- Use ACE inhibitors or ARBs if albuminuria present
- Annual screening for albuminuria and GFR 1, 2
Stage 2 (GFR 60-89 mL/min/1.73 m² with evidence of kidney damage)
- Continue all Stage 1 interventions
- Focus on slowing CKD progression
- Cardiovascular disease risk reduction
- Glycemic control in diabetes (HbA1c target individualized based on comorbidities)
- Lifestyle modifications (smoking cessation, weight management, exercise) 1, 2
Stage 3 (GFR 30-59 mL/min/1.73 m²)
- Continue all previous interventions
- Begin evaluation and treatment of CKD complications:
- Anemia (monitor hemoglobin, iron studies)
- Bone mineral disorders (calcium, phosphorus, PTH)
- Metabolic acidosis (monitor serum bicarbonate)
- Malnutrition (monitor serum albumin)
- Medication dose adjustments
- Consider nephrology referral, especially if rapid progression or complications 1, 2
Stage 4 (GFR 15-29 mL/min/1.73 m²)
- Continue all previous interventions
- Intensify management of complications
- Prepare for kidney replacement therapy
- Mandatory nephrology referral
- Vascular access planning if hemodialysis anticipated
- Education about treatment options (hemodialysis, peritoneal dialysis, transplantation)
- Vaccination updates (hepatitis B, pneumococcal, influenza) 1, 2
Stage 5 (GFR <15 mL/min/1.73 m² or dialysis)
- Initiate kidney replacement therapy when uremic symptoms develop
- Continue management of complications
- Nutritional support
- Psychosocial support
- Transplant evaluation if appropriate 1, 2
Monitoring and Evaluation
The frequency of monitoring depends on CKD stage and progression rate:
- Stage 1-2: Annual assessment of GFR and albuminuria
- Stage 3: Assessment every 6 months
- Stage 4-5: Assessment every 3 months or more frequently 2
Common Pitfalls in CKD Management
- Relying on serum creatinine alone without calculating eGFR
- Dismissing mild GFR reduction in elderly patients
- Delayed nephrology referral for advanced or rapidly progressing CKD
- Inadequate screening for complications in Stage 3-5
- Failure to adjust medication dosages based on declining kidney function
- Overlooking cardiovascular risk reduction in all stages 2
Cardiovascular Risk in CKD
CKD should be considered a coronary heart disease risk equivalent, with cardiovascular disease being the leading cause of death in CKD patients. Risk factors include both traditional (hypertension, diabetes, dyslipidemia) and non-traditional factors (anemia, inflammation, mineral bone disorders, uremic toxins) 1, 3.
Aggressive cardiovascular risk reduction is essential across all CKD stages, with particular attention to blood pressure control, lipid management, and lifestyle modifications 1, 2.