eGFR 45 to 59 mL/min/1.73m²

This is the first band where the number alone can define chronic kidney disease. KDIGO's Table 1 lists "GFR <60 ml/min per 1.73 m2 (GFR categories G3a–G5)" as a criterion in its own right, provided it persists for a minimum of 3 months, and its laboratory standard says reported values under 60 "should be flagged as being low." That flag is why this band starts conversations that G2 does not.

Confirm before you count it. Two KDIGO practice points apply at once. First: "Do not assume chronicity based upon a single abnormal level for eGFR and ACR, as the finding could be the result of a recent acute kidney injury (AKI) event or acute kidney disease (AKD)." Second, Recommendation 1.1.2.1 asks that the GFR category be estimated from creatinine plus cystatin C where cystatin C is available, and KDIGO explains why this band is where it matters: when eGFR was re-estimated with cystatin C, "the group with an eGFR category 45–59 ml/min per 1.73 m2 and ACR <10 mg/g (<1 mg/mmol) was moved to higher risk for all 10 outcomes." The older instruction to measure cystatin C specifically at 45 to 59 without albuminuria was a 2012 KDIGO recommendation that the 2024 guideline retired in favor of that general rule. If the two estimates disagree by 15 points or more, which KDIGO says happens in 25 to 30 percent of people, it calls the uncertainty itself "an indication for nephrology referral."

Monitoring. KDIGO's figure gives the frequency of eGFR and ACR measurement per year for G3a: once at A1, twice at A2, three times at A3, all labeled "Treat." A fall in eGFR of more than 20 percent on a subsequent test "exceeds the expected variability and warrants evaluation"; smaller swings may be noise, since the guideline puts within-person variation at 14 to 20 percent. KDIGO recommends estimating the absolute risk of kidney failure at G3 to G5 with a validated equation (Recommendation 2.2.1, 1A), and uses a 5-year risk of 3 to 5 percent as one trigger for nephrology referral; its referral figure otherwise names eGFR under 30 and a sustained fall of more than 20 percent, so G3a on its own is not a referral criterion.

Treatment. For adults 50 and older at G3a to G5, KDIGO recommends a statin or statin plus ezetimibe (3.15.1.1, 1A). An SGLT2 inhibitor is recommended with type 2 diabetes, or an ACR of 200 mg/g or higher, or heart failure (3.7.1, 3.7.2, both 1A); the suggestion for people without those (3.7.3, 2B) covers eGFR 20 to 45 and does not reach this band, and KDIGO's own site says a focused update on that population is under way. ACE inhibitor or ARB by albuminuria category as at G1 and G2. KDIGO suggests protein intake of 0.8 g/kg a day at G3 to G5 (3.3.1.1, 2C), sodium under 2 g a day, and at least 150 minutes a week of moderate activity. It asks clinicians to "consider GFR when dosing medications cleared by the kidneys," and notes that iodinated contrast at G3a to G5 is managed under the radiology societies' consensus statements. NSAIDs are the over-the-counter drug it names most: chronic indiscriminate use "should be discouraged," with acetaminophen listed as the alternative.