1. Kinetic Glomerular Filtration Rate in Routine Clinical Practice—Applications and Possibilities 
Sheldon Chen 
Advances in Chronic Kidney Disease 
Volume 25, Issue 1, Pages (January 2018)
DOI: /j.ackd
Copyright © 2017 National Kidney Foundation, Inc. Terms and Conditions

2. Figure 1
Microcosm model of steady-state. If creatinine production by the muscle and excretion by the kidney are balanced, then the serum creatinine concentration (SCr) remains stable. Dividing the kidney output of 10 mg of creatinine per cycle by the SCr of 1 mg/dL gives the clearance of 10 dL per cycle, which will be considered a normal kidney function in this small-scale model.
Advances in Chronic Kidney Disease  , DOI: ( /j.ackd )
Copyright © 2017 National Kidney Foundation, Inc. Terms and Conditions

3. Figure 2
Breaking steady-state. If the normal clearance or GFR is reduced by 90%, simulating ATN, then the creatinine excretion falls behind creatinine production. Processing this imbalance through one cycle of the model shows that the serum SCr rises from 1 mg/dL to 1.90 mg/dL. If the low GFR persists, the clearance now acts on a higher ambient serum SCr, so excretion is slightly greater but still less than creatinine production. Processing the imbalance through one more cycle results in a new SCr that rises from 1.90 mg/dL to 2.71 mg/dL, a rate that is slower than before, similar to the course of ATN. Abbreviations: ATN, acute tubular necrosis; GFR, glomerular filtration rate.
Advances in Chronic Kidney Disease  , DOI: ( /j.ackd )
Copyright © 2017 National Kidney Foundation, Inc. Terms and Conditions

4. Figure 3
Applying kinetic GFR to clinical care. A real patient with multiple myeloma developed sepsis-related AKI. The SCr is graphed in red vs time, and the calculated kinetic GFRs are graphed in blue. Phase 1 is typical of ATN. The kinetic GFR drops suddenly and stays persistently low. Phase 2 is a period of CRRT. As the SCr declines, the kinetic GFR shows a more or less steady level of extracorporeal clearance. Phase 3 is discontinuation of CRRT. The kinetic GFR drops immediately back down to prior ATN levels, showing that the native kidneys have not yet recovered. Phase 4 is the transition to hemodialysis, which at first is done daily for the next 3 days. The kinetic GFR ramps up to a level that is acceptable considering that HD is done for only 3–4 hours out of the day. The clearance is seen to improve despite a SCr that is still rising early on. Phase 5 is the first day of HD. The rate of rise in SCr translates into a kinetic GFR at previously low levels. Lack of kidney recovery can be inferred. Abbreviations: AKI, acute kidney injury; ATN, acute tubular necrosis; CRRT, continuous renal replacement therapy; GFR, glomerular filtration rate; HD, hemodialysis. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
Advances in Chronic Kidney Disease  , DOI: ( /j.ackd )
Copyright © 2017 National Kidney Foundation, Inc. Terms and Conditions