Which statement best defines stage 1 CKD?

• A. eGFR ≥90 without any markers of kidney damage
• B. eGFR ≥90 with markers of kidney damage
• C. eGFR 6089 with kidney damage
• D. eGFR <60 with proteinuria

Answer: (B)

Stage 1 CKD is characterized by a normal or near-normal filtration rate (eGFR ≥ 90) combined with evidence of kidney damage. In CKD, damage or abnormalities must be present for a period (typically more than 3 months), and markers of damage can include persistent protein in the urine (albuminuria), imaging abnormalities, or histologic changes. So the best definition is that you have a high eGFR but there are markers indicating kidney damage. The other scenarios either lack evidence of damage with a normal GFR, or describe reduced GFR with damage that places you in a different stage, or describe more advanced kidney function decline.