CKD Stage Classification for GFR 47
A GFR of 47 mL/min/1.73 m² corresponds to CKD Stage 3a (G3a), defined as mildly to moderately decreased kidney function with a GFR range of 45-59 mL/min/1.73 m². 1
GFR-Based Staging
Stage 3a CKD is specifically defined by a GFR of 45-59 mL/min/1.73 m², which encompasses your patient's GFR of 47 mL/min/1.73 m² 1
The subdivision of Stage 3 CKD into 3a and 3b was endorsed by KDIGO and KDOQI because mortality and adverse outcome risks vary greatly between these subgroups, making this distinction clinically important 1
Stage 3b CKD (GFR 30-44 mL/min/1.73 m²) carries significantly higher risks than Stage 3a, with stage 3b patients showing a hazard ratio of 2.99 for progression of renal dysfunction compared to stage 3a patients 2
Complete CKD Classification Requirements
CKD classification requires both GFR category AND albuminuria measurement to fully assess risk and guide treatment decisions 1, 3
The three albuminuria categories are: A1 (<30 mg/g creatinine), A2 (30-299 mg/g creatinine), and A3 (≥300 mg/g creatinine) 1, 3
At GFR 47 with normal albuminuria (A1), the patient would be classified as G3a/A1, which represents moderate risk (yellow zone) requiring annual monitoring 1, 3
If albuminuria is elevated to A2 or A3 levels, the risk increases substantially (orange to red zones), requiring more frequent monitoring (twice to three times yearly) and consideration for nephrology referral 1, 3
Clinical Implications at Stage 3a
Medication dose adjustments are required at this GFR level, particularly for renally cleared drugs 1
ACE inhibitors or ARBs are preferred antihypertensive agents if the patient has diabetes with hypertension and any degree of albuminuria 1
Nephrology referral is recommended if there is severely increased albuminuria (A3 category), regardless of the GFR being in the 3a range 1, 3
Annual monitoring of both eGFR and UACR is the minimum recommended frequency for patients at this stage without elevated albuminuria 1
Important Caveats
The diagnosis of CKD requires abnormalities to be present for >3 months, so a single GFR measurement of 47 does not establish chronic kidney disease without confirmation 1
Approximately 48% of patients with Stage 3 CKD do not progress to more advanced stages over 10 years, particularly those in the 3a subgroup without significant albuminuria 2
Stage 3b CKD (GFR 30-44) was associated with cardiovascular disease in the Framingham Heart Study (HR 1.41), but stage 3a showed only marginal association, highlighting the prognostic difference between these substages 4