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BioMed Research International
Volume 2014, Article ID 542069, 8 pages
Research Article

A Simple Method to Detect Recovery of Glomerular Filtration Rate following Acute Kidney Injury

1Department of Medicine, University of Otago Christchurch, P.O. Box 4345, Christchurch 8140, New Zealand
2St. Mary’s Health Center, Department of Internal Medicine, 6420 Clayton Road, St. Louis, MO 63117, USA

Received 18 November 2013; Accepted 11 May 2014; Published 27 May 2014

Academic Editor: Etienne Macedo

Copyright © 2014 John W. Pickering and John Mellas. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


In acute kidney injury (AKI), elevated plasma creatinine is diagnostic of an earlier loss of glomerular filtration rate (GFR) but not of the concomitant GFR. Only subsequent creatinine changes will inform if GFR had already recovered or not. We hypothesized that the creatinine excretion rate to production rate ratio would provide this information. A retrospective analysis of 482 critically ill patients from two intensive care units (ICU) is shown. Plasma creatinine was measured on ICU entry and 12 hours later. Four-hour creatinine excretion rates ( ) were measured on entry. Creatinine production rates were estimated ( ). The ability of the ratio to predict a decrease in plasma creatinine concentration, identify recovered AKI (≥0.3 mg/dL decrease), and predict AKI (≥0.3 mg/dL increase) was assessed by the area under the receiver operator characteristic curves (AUC). There was a linear relationship between reduced creatinine concentration and ( ; ). predicted a decrease in creatinine (AUC 0.70 (0.65 to 0.74)), identified recovered AKI (0.75 (0.67 to 0.84)), and predicted AKI (0.80 (0.73 to 0.86)). A ratio of the rates of creatinine excretion to estimated production much less than 1 indicated a concomitant GFR below baseline, whereas a ratio much more than 1 indicated a recovering or recovered GFR.