Stages of Chronic Kidney Disease (CKD)
Chronic Kidney Disease is classified into five distinct stages based on glomerular filtration rate (GFR), with specific management strategies required at each stage to reduce morbidity and mortality. 1
CKD Definition and Classification
CKD is defined as kidney damage or GFR <60 mL/min/1.73 m² persisting for at least 3 months. Kidney damage can be identified through:
- Proteinuria/albuminuria
- Abnormalities in urine sediment
- Abnormal blood and urine chemistry measurements
- Abnormal findings on imaging studies 2, 1
The Five Stages of CKD
| Stage | Description | GFR (mL/min/1.73 m²) | Clinical Focus |
|---|---|---|---|
| 1 | Kidney damage with normal or increased GFR | ≥90 | Diagnosis, risk reduction, treating comorbidities |
| 2 | Kidney damage with mild decrease in GFR | 60-89 | Slowing progression, CVD risk reduction |
| 3 | Moderate decrease in GFR | 30-59 | Estimating progression, evaluating complications |
| 4 | Severe decrease in GFR | 15-29 | Managing complications, preparing for replacement therapy |
| 5 | Kidney failure | <15 or dialysis | Replacement therapy if uremia present |
Key Points About CKD Staging
- Stages 1 and 2 require evidence of kidney damage (such as albuminuria) plus the specified GFR range 2
- Stages 3-5 are defined by reduced GFR alone, with or without evidence of kidney damage 2
- At any stage, the degree of albuminuria affects prognosis and treatment decisions 2
- Normal urinary albumin-to-creatinine ratio (UACR) is <30 mg/g Cr, with values ≥30 mg/g Cr indicating increased urinary albumin excretion 2
Clinical Action Plan by Stage
- Stage 1: Screening, CKD risk reduction, diagnosis and treatment of underlying causes
- Stage 2: Continue Stage 1 interventions plus treatment of comorbid conditions, slowing progression, CVD risk reduction
- Stage 3: Continue previous interventions plus estimating progression and evaluating complications
- Stage 4: Continue previous interventions plus evaluating and treating complications, preparing for kidney replacement therapy
- Stage 5: Continue previous interventions plus kidney replacement therapy if uremia present 2, 1
Important Considerations
- Relying solely on serum creatinine can lead to overestimation of kidney function, especially in elderly or malnourished patients 1
- The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is currently recommended as the most accurate creatinine-based method for estimating GFR in routine practice 3
- Cystatin C measurement can be considered for patients with factors that might make creatinine-based equations inaccurate (e.g., high or low muscle mass) 3
- Monitoring frequency should increase with advancing CKD stages, with more frequent assessment of complications in stages 4-5 1
By understanding these stages and their implications, healthcare providers can implement appropriate interventions at each stage to slow disease progression and reduce the risk of complications.