Monitoring of plasma creatinine and urinary gamma-glutamyl transpeptidase improves detection of acute kidney injury by more than 20%

Objectives: We sought to determine how early we can detect acute kidney injury inpatients at intensive care unit admission by combining the use of plasma creatinine and urinary gamma-glutamyl transpeptidase. Design: Prospective study including development (n = 100) and validation (n = 56) cohorts. Settings: Intensive care unit of a university hospital. Interventions: None. Measurements and Main Results: To determine acute kidney injury, we subtracted measured creatinine clearance from theoretical creatinine clearance with a 25% reduction signifying acute kidney injury. Its incidence in 100 consecutive patients was 36%. An indexed urinary gamma-glutamyl transpeptidase-to-urinary creatinine ratio was significantly increased in the patients with acute kidney injury and did not correlate with plasma creatinine (p = .3). Using a predefined threshold of indexed urinary gamma-glutamyl transpeptidase-to-urinary creatinine ratio (>12.4 units/mmol) and plasma creatinine (>89 mu mol/L), acute kidney injury detection was significantly improved, making it possible to detect 22 (22%) additional patients with acute kidney injury. This finding was confirmed in the validation group. The rates of false-positive results were 30% and 19% in the data development and internal validation cohorts, respectively. Conclusions: The use of low-cost, widely available markers (creatinine and urinary gamma-glutamyl transpeptidase) increases the detection of acute kidney injury. Further studies are needed to determine the impact on outcome with the use of these biomarkers. (Crit Care Med 2011; 39:52-56)