From the Guidelines
Kidney failure is staged using the Kidney Disease Improving Global Outcomes (KDIGO) classification system, which divides chronic kidney disease into five stages based primarily on estimated glomerular filtration rate (eGFR). The staging of kidney failure is crucial for determining the appropriate treatment strategies and management plans. The KDIGO classification system is based on the level of kidney function, with Stage 1 indicating kidney damage with normal or increased eGFR (≥90 mL/min/1.73m²), Stage 2 representing mild reduction in eGFR (60-89 mL/min/1.73m²), Stage 3 divided into 3a (45-59 mL/min/1.73m²) and 3b (30-44 mL/min/1.73m²) indicating moderate reduction, Stage 4 showing severe reduction (15-29 mL/min/1.73m²), and Stage 5 representing kidney failure (<15 mL/min/1.73m² or dialysis) 1. In addition to eGFR, albuminuria categories are used as a secondary marker, classified as A1 (normal to mildly increased), A2 (moderately increased), or A3 (severely increased) 1. This dual classification system provides a more comprehensive assessment of kidney function and risk stratification. Regular monitoring of both eGFR and albuminuria is essential for proper staging and management, with testing frequency increasing as kidney function declines 1. The staging system helps clinicians determine appropriate treatment strategies, medication adjustments, and timing for referral to nephrology specialists 1. Some key points to consider when staging kidney failure include:
- The level of kidney function, as measured by eGFR, is the primary factor in determining the stage of kidney disease 1.
- Albuminuria categories are used as a secondary marker to assess kidney damage and risk stratification 1.
- Regular monitoring of eGFR and albuminuria is crucial for proper staging and management 1.
- The staging system helps clinicians determine appropriate treatment strategies, medication adjustments, and timing for referral to nephrology specialists 1.
- Patients with chronic kidney disease should be referred to a specialist for consultation and comanagement if the patient's personal physician cannot adequately evaluate and treat the patient 1.
From the Research
Staging Kidney Failure
The guidelines for staging kidney failure are based on the level of glomerular filtration rate (GFR) and are classified into five stages 2. The stages are as follows:
- Stage 1: Kidney damage with normal or high GFR (>90 mL/min/1.73 m2)
- Stage 2: Kidney damage with mild decrease in GFR (60-89 mL/min/1.73 m2)
- Stage 3: Moderate decrease in GFR (30-59 mL/min/1.73 m2)
- Stage 4: Severe decrease in GFR (15-29 mL/min/1.73 m2)
- Stage 5: Kidney failure (GFR <15 mL/min/1.73 m2 or on dialysis)
Classification of Chronic Kidney Disease (CKD)
CKD is defined as kidney damage or GFR <60 mL/min/1.73 m2 for 3 months or more, irrespective of cause 2. The K/DOQI definition and classification were accepted, with clarifications. Kidney disease severity is classified into five stages according to the level of GFR.
Importance of Albuminuria Monitoring
Albuminuria monitoring is critical for optimal risk stratification in CKD 3. The incidence rates of mortality and adverse cardiovascular and renal outcomes increase with declining baseline eGFR, and particularly with increasing albuminuria.
Treatment and Management
Treatment and management of CKD involve maintaining phosphorus and calcium serum concentrations within recommended guidelines 4. Phosphate-binding compounds, such as calcium acetate, sevelamer, and lanthanum carbonate, can help maintain serum phosphate levels near the recommended concentration. Erythropoiesis-stimulating agents (ESAs) are commonly used to treat anemia in people with CKD 5. However, their use has been associated with cardiovascular events.
Guidelines and Adherence
The KDIGO 2012 guidelines classify CKD risk or prognosis using estimated GFR and urinary albumin-to-creatinine ratio (UACR) 3. Despite clear evidence of utility, there is low adherence to these guidelines, highlighting an imperative for more regular UACR testing in clinical practice. Revised KDIGO CKD guidelines have been published in 2024 with salient modifications to the previous version 6.