Kinetic Glomerular Filtration Rate Estimation Compared With Other Formulas for Evaluating Acute Kidney Injury Stage Early After Kidney Donation.

OBJECTIVES: Kinetic glomerular filtration rate estimation may have more power and versatility than the Modification of Diet in Renal Disease or Cockcroft-Gault formula for evaluating kidney function when plasma creatinine fluctuates rapidly. After kidney donation, glomerular filtration rate rapidly fluctuates in otherwise healthy patients. We compared 3 formulas for estimating glomerular filtration rate: kinetic, Modification of Diet in Renal Disease, and Cockcroft-Gault, for determining stages of acute kidney injury early after kidney donation. MATERIALS AND METHODS: In 42 living kidney donors, we measured serum creatinine, cystatin C, neutrophil gelatinase-associated lipocalin, and glomerular filtration rates before uninephrectomy and 3 days afterward. To estimate glomerular filtration rate, we used Cockcroft-Gault, Modification of Diet in Renal Disease, and kinetic equations. We sought the most accurate formula for staging acute kidney injury according to the risk, injury, failure, loss, and end-stage criteria. RESULTS: The kinetic glomerular filtration rate model found more cases of stage 3 acute kidney injury than did the Modification of Diet in Renal Disease or Cockcroft-Gault formula. Receiver operating characteristic curves showed that the kinetic glomerular filtration rate model had more sensitivity and specificity than the Cockroft-Gault formula for discriminating among risk, injury, failure, loss, and end-stage criteria stages of acute kidney injury, based on serum creatinine changes. On day 2 after donation, a more sensitive marker with a shorter half-life (serum neutrophil gelatinase-associated lipocalin) was more significantly correlated with kinetic glomerular filtration rate estimation. CONCLUSIONS: The kinetic glomerular filtration rate model was able to discriminate stages of acute kidney injury early after kidney donation according to risk, injury, failure, loss, and end-stage criteria better than the Modification of Diet in Renal Disease or Cockcroft-Gault formulas. The kinetic model detected failure-stage acute kidney injury ≥ 1 to 2 days earlier than the MDRD formula, CG formula detected no failure.