Chronic Kidney Disease Staging and Management
Chronic Kidney Disease (CKD) is classified into five stages based on glomerular filtration rate (GFR) and evidence of kidney damage, with each stage requiring specific management approaches tailored to disease severity.
Definition and Classification of CKD
- CKD is defined as abnormalities of kidney structure or function, present for >3 months, with implications for health 1
- Diagnosis requires either kidney damage markers or reduced GFR (<60 mL/min/1.73 m²) for at least 3 months 1, 2
- CKD should be classified based on cause, GFR category, and albuminuria category (CGA) 1
CKD Staging
- Stage 1: GFR ≥90 mL/min/1.73 m² with evidence of kidney damage (e.g., albuminuria, structural abnormalities) 1, 2
- Stage 2: GFR 60-89 mL/min/1.73 m² with evidence of kidney damage 1, 2
- Stage 3a: GFR 45-59 mL/min/1.73 m² 1, 2
- Stage 3b: GFR 30-44 mL/min/1.73 m² 1, 2
- Stage 4: GFR 15-29 mL/min/1.73 m² 1, 2
- Stage 5: GFR <15 mL/min/1.73 m² or kidney failure requiring dialysis 1, 2
Albuminuria Categories
- A1: Normal to mildly increased (<30 mg/g) 2
- A2: Moderately increased (30-300 mg/g) 2
- A3: Severely increased (>300 mg/g) 2
Clinical Action Plan by CKD Stage
Stage 1-2 (GFR ≥60 mL/min/1.73 m²)
- Focus on diagnosis and treatment of underlying conditions 1, 3
- Implement CKD risk reduction strategies 1, 3
- Treat comorbid conditions 1
- Begin cardiovascular disease risk reduction 3
Stage 3 (GFR 30-59 mL/min/1.73 m²)
- Estimate progression rate 1, 2
- Begin evaluation for complications 1, 2
- Monitor for hypertension, which approaches 80% prevalence in advanced CKD 1
- Screen for anemia, which becomes more prevalent as GFR falls below 60 mL/min/1.73 m² 1
Stage 4 (GFR 15-29 mL/min/1.73 m²)
- Intensify management of complications 1, 2
- Prepare for kidney replacement therapy 1, 3
- Refer to nephrology for consultation and co-management 3
- Monitor serum calcium and phosphorus every 3-6 months; PTH every 6-12 months 1
Stage 5 (GFR <15 mL/min/1.73 m²)
- Implement kidney replacement therapy if uremia is present 1, 3
- Monitor serum calcium and phosphorus every 1-3 months; PTH every 3-6 months 1
- Measure alkaline phosphatases annually or more frequently with elevated PTH 1
Management of CKD Complications
Cardiovascular Disease
- Cardiovascular complications are the most common cause of death in CKD patients 4
- Implement statin therapy and blood pressure management for cardiovascular risk reduction 5
Hypertension
- Use ACE inhibitors or ARBs as first-line agents, especially with albuminuria 5, 6
- Target blood pressure should be individualized based on age and comorbidities 5
Metabolic Abnormalities
- Monitor and treat hyperkalemia, metabolic acidosis, and hyperphosphatemia 5
- Assess vitamin D status and treat deficiency 5, 6
- Screen for secondary hyperparathyroidism 5
Anemia
- Assess and treat anemia by addressing underlying causes 1
- Consider erythropoiesis-stimulating agents when appropriate 4
- Use ACE inhibitors or ARBs for initial treatment of erythrocytosis 1
Bone and Mineral Disorders
- In CKD stages 3-5, measure 25(OH)D (calcidiol) levels 1
- Correct vitamin D deficiency using treatment strategies recommended for the general population 1
- Consider bone mineral density testing in early stages with risk factors 1
Monitoring Recommendations
- Complete blood count monitoring schedule 1:
- Daily for 7 days or until hospital discharge
- 2-3 times per week for weeks 2-4
- Weekly for months 2-3
- Monthly for months 4-12
- At least annually thereafter
Special Considerations
- Age-related decline in GFR should not be considered "normal aging" as decreased GFR in the elderly remains an independent predictor of adverse outcomes 3
- The risk of having multiple complications increases substantially when GFR falls below 30 mL/min/1.73 m² 1, 2
- Avoid nephrotoxic medications (e.g., NSAIDs) in all CKD stages 5
- Adjust medication dosing for kidney function (e.g., antibiotics, oral hypoglycemics) 5