A bedside clinical tool using creatinine kinetics to predict worsening renal injury and early recovery

BACKGROUND: Changing creatinine concentrations during acute renal failure are often confusing to clinicians to interpret and can cloud the patient’s true current state of renal injury. By modifying the formula for kinetic estimate of glomerular filtration rate (KeGFR), a simple bedside clinical tool can be used to identify subtle changes in renal function. METHODS: The KeGFR was rewritten to instead calculate a predicted peak creatinine after renal injury. By comparing the changes in predicted peak creatinine at two or more subsequent time intervals, the patient’s current state of renal injury can be determined: whether improving, worsening or unchanged from prior. RESULTS: Three case examples are provided using the equation for predicted peak creatinine. In each case, the creatinine concentration has continued to rise at three sequentially measured times. The change in predicted peak creatinine is analyzed for each case, demonstrating scenarios involving (i) improving renal injury, (ii) unchanged renal injury continued by unfavorable hemodynamics and (iii) worsening renal injury despite interventions. CONCLUSIONS: The use of this model may provide clinicians with an easy bedside tool to assess a patient’s state of acute kidney injury. Reassessment of how the creatinine is changing is already a nonquantitative part of a nephrologist's approach to acute kidney injury. Providing an assessment of the patient's changing renal function would be a useful addition to potentially detect early renal recovery or worsening renal injury and appropriately adjust treatment strategies.