Stage 2 Chronic Kidney Disease: Creatinine Clearance Range
Stage 2 chronic kidney disease is defined by a creatinine clearance (or estimated GFR) of 60-89 mL/min/1.73 m² in the presence of kidney damage. 1
Definition and Classification
Stage 2 CKD represents mildly decreased kidney function with evidence of kidney damage, according to the K/DOQI classification system 1:
- GFR range: 60-89 mL/min/1.73 m² 1
- Must have evidence of kidney damage (such as proteinuria, hematuria, or structural abnormalities on imaging) 1
- Without evidence of kidney damage, a GFR in this range would be classified as Stage 1 CKD (if GFR ≥90) or potentially normal kidney function 1
Clinical Context and Measurement
The creatinine clearance in Stage 2 CKD can be assessed through multiple methods 1:
- Estimated GFR (eGFR) calculated from serum creatinine using validated equations like MDRD 1
- 24-hour urine creatinine clearance measurement 2
- The definition requires this level of function to persist for at least 3 months to establish chronicity 1
Important Clinical Considerations
Metabolic complications are uncommon at this stage. Research demonstrates that metabolic abnormalities associated with CKD (hyperparathyroidism, anemia, acidosis, hyperkalemia, hyperphosphatemia) typically begin appearing when GFR falls below 50-60 mL/min/1.73 m², meaning Stage 2 CKD patients generally do not yet manifest these complications 3:
- Hyperparathyroidism prevalence increases significantly only when GFR drops below 60 mL/min/1.73 m² 3
- Anemia becomes prevalent at GFR thresholds below 44 mL/min/1.73 m² 3
- Acidosis, hyperkalemia, and hyperphosphatemia typically emerge at even lower GFR levels (37-40 mL/min/1.73 m²) 3
Drug dosing adjustments are typically not required. Most medications that require renal dose adjustment begin modifications at creatinine clearance <50 mL/min 1, meaning Stage 2 CKD patients with clearances of 60-89 mL/min generally receive standard dosing.
Common Pitfall
A critical distinction exists between Stage 1 and Stage 2 CKD: both can have GFR >60 mL/min, but Stage 2 specifically indicates mildly decreased function (60-89 mL/min) with kidney damage, while Stage 1 indicates normal or high GFR (≥90 mL/min) with kidney damage 1. The presence of kidney damage markers (proteinuria, structural abnormalities) is essential for diagnosis at these early stages 1.