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Open Access Highly Accessed Research

Four hour creatinine clearance is better than plasma creatinine for monitoring renal function in critically ill patients

John W Pickering1*, Christopher M Frampton1, Robert J Walker2, Geoffrey M Shaw13 and Zoltán H Endre14

Author Affiliations

1 Christchurch Kidney Research Group, Department of Medicine, University of Otago, Riccarton Avenue, Christchurch 8140, New Zealand

2 Department of Medicine and Surgery, University of Otago, Leith Walk, Dunedin 9054, Dunedin, New Zealand

3 Intensive Care, Christchurch Hospital, Riccarton Avenue, Christchurch 8140, New Zealand

4 Department of Nephrology, Prince of Wales Clinical School, University of New South Wales, Barker St, Randwick, Sydney, NSW 2031, Australia

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Critical Care 2012, 16:R107  doi:10.1186/cc11391


See related commentary by Molitoris http://ccforum.com/content/16/5/158

Published: 19 June 2012

Abstract

Introduction

Acute kidney injury (AKI) diagnosis is based on an increase in plasma creatinine, which is a slowly changing surrogate of decreased glomerular filtration rate. We investigated whether serial creatinine clearance, a direct measure of the glomerular filtration rate, provided more timely and accurate information on renal function than serial plasma creatinine in critically ill patients.

Methods

Serial plasma creatinine and 4-hour creatinine clearance were measured 12-hourly for 24 hours and then daily in 484 patients. AKI was defined either as > 50% increase in plasma creatinine from baseline, or > 33.3% decrease in creatinine clearance. The diagnostic and predictive performance of the two AKI definitions were compared.

Results

Creatinine clearance decrease diagnosed AKI in 24% of those not diagnosed by plasma creatinine increase on entry. These patients entered the ICU sooner after insult than those diagnosed with AKI by plasma creatinine elevation (P = 0.0041). Mortality and dialysis requirement increased with the change in creatinine clearance-acute kidney injury severity class (P = 0.0021). Amongst patients with plasma creatinine < 1.24 mg/dl on entry, creatinine clearance improved the prediction of AKI considerably (Net Reclassification Improvement 83%, Integrated Discrimination Improvement 0.29). On-entry, creatinine clearance associated with AKI severity and duration (P < 0.0001) predicted dialysis need (area under the curve: 0.75) and death (0.61). A > 33.3% decrease in creatinine clearance over the first 12 hours was associated with a 2.0-fold increased relative risk of dialysis or death.

Conclusions

Repeated 4-hour creatinine clearance measurements in critically ill patients allow earlier detection of AKI, as well as progression and recovery compared to plasma creatinine.

Trial Registration

Australian New Zealand Clinical Trials Registry ACTRN012606000032550.