Relationship between acute kidney injury and serum procalcitonin (PCT) concentration in critically ill patients with influenza infection.

INTRODUCTION: Serum procalcitonin (PCT) concentration could be increased in patients with renal dysfunction in the absence of bacterial infection.

OBJECTIVE: To determine the interactions among serum renal biomarkers of acute kidney injury (AKI) and serum PCT concentration, in patients admitted to the intensive care unit (ICU) due to lung influenza infection.

DESIGN: Secondary analysis of a prospective multicentre observational study.

SETTING: 148 Spanish ICUs.

PATIENTS: ICU patients admitted with influenza infection without bacterial co-infection. Clinical, laboratory and hemodynamic variables were recorded. AKI was classified as AKI I or II based on creatinine (Cr) concentrations (≥1.60-2.50mg/dL and Cr≥2.51-3.99mg/dL, respectively). Patients with chronic renal disease, receiving renal replacement treatment or with Cr>4mg/dL were excluded. Spearman's correlation, simple and multiple linear regression analysis were performed.

INTERVENTIONS: None.

RESULTS: Out of 663 patients included in the study, 52 (8.2%) and 10 (1.6%) developed AKI I and II, respectively. Patients with AKI were significantly older, had more comorbid conditions and were more severally ill. PCT concentrations were higher in patients with AKI (2.62 [0.60-10.0]ng/mL vs. 0.40 [0.13-1.20]ng/mL, p=0.002). Weak correlations between Cr/PCT (rho=0.18) and Urea (U)/PCT (rho=0.19) were identified. Simple linear regression showed poor interaction between Cr/U and PCT concentrations (Cr R2 =0.03 and U R2 =0.018). Similar results were observed during multiple linear regression analysis (Cr R2 =0.046 and U R2 =0.013).

CONCLUSIONS: Although PCT concentrations were slightly higher in patients with AKI, high PCT concentrations are not explained by AKI and could be warning sign of a potential bacterial infection.