Objective: To evaluate whether microalbuminuria increases in post-operative patients developing sepsis, and whether it is correlated to the sepsis severity score (SOFA) and the PaO₂/FIO₂ ratio.

Design: Prospective study.

Setting: University intensive care unit.

Patient population: Fifty-five post-operative ASA II-III patients admitted to the ICU after major abdominal or vascular surgery.

Interventions: None.

Measurements and results: Urine collection and measurement of microalbuminuria and urinary creatinine on admission and again as soon as sepsis developed or at the end of the study (72 h after admission). Results are expressed as the microalbuminuria/creatinine ratio (MACR). The MACR significantly increased as soon as sepsis (defined according to the ACPP/SCCM Consensus Conference) appeared. The MACR positively correlated to the SOFA score, but had no relation to the PaO₂/FIO₂ ratio. Patients not developing sepsis did not show any increase in the MACR during the study period.

Conclusions: Post-operative patients developing sepsis, unlike those with an uncomplicated post-operative evolution, showed an increase in glomerular permeability which was revealed by MACR. The increase in the MACR was positively correlated to the increase in SOFA score, while it had no relation to the PaO_2/FIO₂ ratio.