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each condition based on GFR and different magnitudes of increase in SCr. To illustrate the relationship of changes in SCr to changes in eGFR, we simulated changes in eGFR that would result from changes in SCr corresponding to the KDIGO definition of AKI in the Chronic Kidney Disease Epidemiology Collaboration cohort.67,68 Figure 6 shows the relationship of these changes in eGFR to the definition and stages of AKI. Not all patients with AKI would meet the eGFR criteria for the definition of AKD. GFR/SCr algorithm Figure 7 provides a diagnostic algorithm based on a sequential approach through three questions: i) Is GFR decreased or is SCr increased (according to the criteria in Table 12)?; ii) Is SCr increasing or GFR decreasing (according to the criteria in Table 12)?; and iii) Does the decrease in GFR or increase in SCr resolve within 3 months? Based on a ‘‘yes’’ or ‘‘no’’ response to these three sequential questions, all combinations of AKI, AKD, and CKD can be identified. In this section, we review the algorithm and illustrate its use for classification of patients with acute and chronic kidney disease in two previously reported cohorts. http://www.kidney-international.org chapter 2.5 & 2012 KDIGO Table 11 | Definitions of AKI, CKD, and AKD Functional criteria Structural criteria AKI Increase in SCr by 50% within 7 days, OR Increase in SCr by 0.3 mg/dl (26.5 mmol/l) within 2 days, OR Oliguria No criteria CKD GFR o60 ml/min per 1.73 m2 for 43 months Kidney damage for 43 months AKD AKI, OR GFR o60 ml/min per 1.73 m2 for o3 months, OR Decrease in GFR by X35% or increase in SCr by 450% for o3 months Kidney damage for o3 months NKD GFR X60 ml/min per 1.73 m2 Stable SCr No damage GFR assessed from measured or estimated GFR. Estimated GFR does not reflect measured GFR in AKI as accurately as in CKD. Kidney damage assessed by pathology, urine or blood markers, imaging, and—for CKD—presence of a kidney transplant. NKD indicates no functional or structural criteria according to the definitions for AKI, AKD, or CKD. Clinical judgment is required for individual patient decision-making regarding the extent of evaluation that is necessary to assess kidney function and structure. AKD, acute kidney diseases and disorders; AKI, acute kidney injury; CKD, chronic kidney disease; GFR, glomerular filtration rate; NKD, no known kidney disease; SCr, serum creatinine. Table 12 | Examples of AKI, CKD, and AKD based on GFR and increases in SCr Baseline GFR (ml/min per 1.73 m2 ) Increase in SCr during 7 consecutive days GFR during next 3 months Diagnosis 460 41.5 NA AKI 460 o1.5 o60 AKD without AKI 460 o1.5 460 NKD Baseline GFR (ml/min per 1.73 m2 ) Change in SCr during next 7 days GFR during next 3 months Diagnosis o60 41.5 NA AKI + CKD o60 o1.5 435% decrease AKD without AKI + CKD o60 o1.5 o35% decrease CKD GFR assessed from measured or estimated GFR. Estimated GFR does not reflect measured GFR in AKI as accurately as in CKD. AKD, acute kidney diseases and disorders; AKI, acute kidney injury; CKD, chronic kidney disease; GFR, glomerular filtration rate; NKD, no known kidney disease; SCr, serum creatinine. Kidney International Supplements (2012) 2, 19–36 33 The answer to Question 1 requires ascertainment of an index GFR/SCr as well during the prior 3 months. The index GFR/SCr can be assigned as any of the GFR/SCr measures during the interval of observation. The answer classifies patients into three categories: NKD, AKD, and CKD. Question 2 requires repeat ascertainment of kidney function after the index measure. ‘‘No’’ indicates that the increase in SCr or decrease in GFR after the index measure does not Figure 6 | Chronic Kidney Disease Epidemiology Collaboration cohort changes in eGFR and final eGFR corresponding to KDIGO definition and stages of AKI. Panels (a) and (b) show the final eGFR and the percent changes in eGFR, respectively, corresponding to the KDIGO definition and stages of AKI. The horizontal line in panel a and b indicates the threshold value for AKD (o60 ml/min per 1.73 m2 and 435% reduction in initial GFR, respectively). Points above the horizontal line indicate subjects who meet the SCr criteria for the definition of AKI but do not meet eGFR criteria for the definition of AKD. AKD, acute kidney disorder/disease; AKI, acute kidney injury; eGFR, estimated glomerular filtration rate; KDIGO, Kidney Disease: Improving Global Outcomes; SCr, serum creatinine.