Significant microalbuminuria, on admission to the ICU, may indicate AKI in patients with sepsis

Introduction

In sepsis, a generalised inflammatory onslaught causes systemic endothelial dysfunction; the glomerular manifestation of which is microalbuminuria. Recent histopathological evidence of extensive glomerular capillary infiltration by leucocytes in septic AKI suggests that endothelial dysfunction may play a particularly important role in this condition compared with patients with other causes of AKI. Markers of endothelial dysfunction such as microalbuminuria may therefore have a potential diagnostic role in septic AKI.

Methods

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. Two hundred and sixty-six patients were recruited between January 2007 and December 2008. Patients with an ICU stay of less than 24 hours, pregnancy, menstruation, anuria, hematuria, proteinuria due to renal and post-renal structural diseases were excluded. Sepsis was diagnosed by the ACCP/SCCM criteria; AKI was identified on admission using the RIFLE criteria.

Results

Of the 266 patients studied, 130 patients had no AKI while 136 patients had AKI as classified by the RIFLE criteria. Of these 136 patients, 59 patients were in the Risk category, 62 in the Injury and 15 patients in the Failure, of which 26 patients (9.8%) needed RRT. For the entire cohort, median age was 61.5 years, 61% were male, median APACHE II score was 15. Of these, 56 (21%) of patients died on the ICU. ACR showed significant correlation with serum creatinine values (P = 0.0049, Spearman rank correlation (r) = 0.173) and was negatively associated with estimated GFR (P = 0.0002, r = -0.225). The median level of ACR (204.1 mg/g, (IQR 119.7 to 402.0)) of patients with septic AKI (n = 66) on admission to the ICU was significantly greater (P < 0.0001) than the median ACR level of 67.1 mg/g (IQR 32.99 to 129.9) of patients who had AKI from other causes (n = 70). Patients of sepsis who had developed AKI also had higher ACR than those who did not (n = 51) (ACR 119.3 mg/g (IQR 37.02 to 354.3)) (P = 0.0137).

Conclusions

Presence of significant microalbuminuria on admission to the ITU may be an early indicator of AKI in sepsis patients.