AKI KDIGO definition (AKI is a subcategory of AKD): oliguria for >6 h, rise in SCr level by >0.3 mg/dl in 2 d or by > 50% in 1 wk ARF, ARI AKI classification KDIGO classification by cause and stage preferred rather than stage alone; e.g., a patient with AKI stage 3 due to ATN; classification applies to all AKI stages Previous classifications, including RIFLE and AKIN (the KDIGO classification harmonized these prior definitions) AKI stages KDIGO definition (applicable only to people with AKI) AKI stage 1 Serum creatinine and/or urine output criteria AKI stage 2 Serum creatinine and/or urine output criteria AKI stage 3 Serum creatinine and/or urine output criteria Preferred term Suggested abbreviationsa Rationale/explanation Terms to avoid Part 4. Chronic kidney disease (CKD) Disease duration >3 mo Chronic renal failure (CRF); ESRD; renal/ kidney impairment, insufficiency, dysfunction CKD KDIGO definition: GFR 3 mo CRF; ESRD; renal/kidney impairment, insufficiency, dysfunction Table 3 (Parts 1–5) | (Continued) Kidney Disease: Improving Global Outcomes (KDIGO) kidney function and disease glossary: suggested terms to describe kidney function and kidney disease and criteria and measures defining them Preferred term Suggested abbreviationsa Rationale/explanation Terms to avoid KDIGO conference report AS Levey et al.: KDIGO nomenclature for kidney function and disease 1124 Kidney International (2020) 97, 1117–1129 Preferred term Suggested abbreviationsa Rationale/explanation Terms to avoid CKD classification KDIGO CGA classification by cause, GFR category (G1–G5), and albuminuria category (A1–A3), see below for definitions of G and A categories. For example, a patient with CKD G1, A3 due to diabetes, or a cohort with CKD G4–G5, A1–A3 of any cause. Note that CKD classification is only applicable to people with CKD, so a patient could not be classified as “CKD G2, A1” if there was no other evidence of kidney damage. Mild, moderate, severe, early, advanced CKD; CKD stage 1–5 (complete description preferred rather than G category alone) CKD without KRT CKD without KRT CKD G1–G5, A1–A3 of any cause, not receiving dialysis or transplantation ND-CKD (non-dialysis CKD), NDD-CKD (non–dialysis-dependent CKD), predialysis CKD, pre-ESRD CKD CKD risk categories KDIGO definitions (colors refer to heat map, Supplementary Figure S1) unless otherwise defined; risk depends on the outcome being considered Mild, moderate, severe, early, advanced CKD CKD risk category—low Low risk Refers to G1A1, G2A1 (green) CKD risk category— moderately high Moderate risk Refers to G1A2, G2A2, G3aA1 (yellow) CKD risk category–high High risk Refers to G1A3, G2A3, G3aA2, G3bA1 (orange) CKD risk category–very high Very high risk Refers to G3aA3, G3bA2, G3bA3, G4A1, G4A2, G4A3, G5A1, G5A2, G5A3 (red) CKD progression Refers to worsening GFR or albuminuria. Other biomarkers not included. There is not yet consensus on use of specific terms to describe the timing (e.g., early, late) or rate (fast, slow) of progression. Use of specific terms should be defined in methods. Further specification may be required: GFR decline may occur during therapy for other conditions, which may not be considered as CKD progression. CKD remission Refers to improving GFR or albuminuria. Criteria depend on disease. Use of specific terms should be defined in methods. Preferred term Suggested abbreviationsa Rationale/explanation Terms to avoid Part 5. Kidney measures Applies to people with or without kidney disease Consider measurement issues (methods) and variability (multiple measures may improve classification) Glomerular filtration rate and clearance GFR and creatinine clearance are not synonymous Glomerular filtration rate GFR Units must be specified (ml/min per 1.73 m2 or ml/min) Measured glomerular filtration rate mGFR Clearance methods and exogenous filtration markers should be noted separately in methods Estimated glomerular filtration rate eGFR Estimating equations (e.g., CKD-EPI and MDRD Study) and filtration markers (e.g., creatinine and cystatin C) should be noted separately in methods Estimated glomerular filtration rate; marker eGFRcr eGFRcys eGFRcr-cys eGFR using creatinine eGFR using cystatin C eGFR using creatinine and cystatin C Clearance Cl Solute must be specified; units must be specified (ml/min per 1.73 m2 or ml/min) Measured clearance mCl Clearance methods and markers should be noted separately in methods Measured clearance; marker mClUN mClcr mClUN-cr mCl using urea nitrogen mCl using creatinine mCl using urea nitrogen and creatinine Estimated clearance eCl Estimating equations (e.g., Cockcroft-Gault) and markers should be noted separately in methods Estimated clearance; marker eClcr eCl using creatinine Table 3 (Parts 1–5) | (Continued) (Continued on next page) AS Levey et al.: KDIGO nomenclature for kidney function and disease KDIGO conference report Kidney International (2020) 97, 1117–1129 1125 cause of disease, level of GFR (6 categories), and level of albuminuria (3 categories), collectively known as the CGA classification, rather than GFR alone (5 stages used in the KDOQI guideline).7,29 The albuminuria and GFR categories have been grouped into 4 risk categories according to their associations with risks for various outcomes (all-cause and cardiovascular mortality, kidney failure requiring