KDIGO GFR Category G2
KDIGO GFR category G2 represents a mildly decreased kidney function with an estimated glomerular filtration rate (eGFR) of 60-89 mL/min/1.73 m², and importantly, this category alone does NOT constitute chronic kidney disease (CKD) unless accompanied by evidence of kidney damage such as albuminuria. 1
Definition and Classification
GFR Category G2 Criteria:
- eGFR range: 60-89 mL/min/1.73 m² 1
- Description: Kidney damage with mild decrease in GFR 1
- Critical requirement: Must have markers of kidney damage (such as albuminuria ≥30 mg/g) present for ≥3 months to qualify as CKD 1
Clinical Significance
Key Point: G2 alone without kidney damage markers is NOT CKD. 1 The presence of structural or functional kidney abnormalities (particularly albuminuria) is essential for the diagnosis of CKD in this GFR range. 1, 2
When G2 Indicates CKD:
- Albuminuria (albumin-to-creatinine ratio ≥30 mg/g) is present 1, 2
- Other markers of kidney damage exist (abnormal urinary sediment, structural abnormalities on imaging, or biopsy-proven kidney disease) 1
- Abnormalities persist for ≥3 months 1
Prognosis and Risk Stratification
The prognosis in G2 varies dramatically based on albuminuria level: 1, 3
- G2 with normal albuminuria (<30 mg/g): Low risk for progression and mortality 3
- G2 with moderately increased albuminuria (30-299 mg/g): Moderate risk 3
- G2 with severely increased albuminuria (≥300 mg/g): High risk for CKD progression and cardiovascular events 3, 4
Clinical Management Approach
Monitoring Frequency: 1
- Assess eGFR and albuminuria at least annually 1
- More frequent monitoring if albuminuria is present or other risk factors exist 1
Interventions for G2 with Kidney Damage: 1
- Lifestyle modifications: Smoking cessation, weight management 1
- Blood pressure optimization: Target individualized based on albuminuria level 1
- RAS inhibition: If albuminuria ≥30 mg/g is present 1
- SGLT2 inhibitors: For patients with type 2 diabetes and albuminuria 1
- Identify and treat underlying cause of kidney damage 1
- Avoid nephrotoxins and adjust medication dosages appropriately 1
Common Clinical Pitfalls
Do not diagnose CKD based on G2 alone. 1 A healthy kidney donor with eGFR of 65 mL/min/1.73 m² and no albuminuria does NOT have CKD, despite being in the G2 range. 1
Small fluctuations in eGFR are common and not necessarily indicative of progression. 1 Confirm changes with repeat testing before concluding disease progression. 1
Consider cystatin C-based eGFR estimation if there are concerns about creatinine-based estimates being inaccurate (extremes of muscle mass, dietary factors). 1, 5