Microalbuminuria: a biomarker of sepsis

Introduction

Assessment of microalbuminuria as a diagnostic tool in predicting sepsis in the critically ill patient.

Methods

A prospective observational study in a 20-bed ICU in a tertiary-care hospital. Microalbuminuria estimated as the spot urine albumin–creatinine ratio (ACR, mg/g) was measured on ICU admission (ACR1) and after 24 hours (ACR2). A total of 242 patients were recruited for the study between January 2007 and May 2008. Patients with an ICU stay of less than 24 hours, pregnancy, menstruation, anuria, hematuria, urinary tract infection, and proteinuria due to renal and postrenal structural diseases were excluded.

Results

Patients with sepsis (n = 95) had a significantly higher median ACR1 (145.8 (IQR 46 to 305)) and ACR2 (104.3 (IQR 33 to 179)) in comparison with those without sepsis (n = 147) (ACR1 = 56.6 (IQR 27 to 111) and ACR2 = 37.8 (IQR 18 to 93)) (P < 0.0001) (Figure 1). In a receiver operating characteristic curve analysis, ACR1 emerged as the most reliable indicator of sepsis (area under curve (AUC) of ACR1 = 0.710 >AUC of ACR2 = 0.694). ACR1 concentration of 145.7 mg/g had sensitivity of 50.5% and specificity of 87.1% with positive predictive value of 71.6% and negative predictive value of 73.1% in diagnosis of sepsis.

Figure 1

Comparison of ACR1 between sepsis and nonsepsis patients.

Conclusion

Absence of significant microalbuminuria at the time of ICU admission is unlikely to be associated with sepsis.