Changes of Procalcitonin Kinetics According to Renal Clearance in Critically Ill Patients with Primary Gram-Negative Bloodstream Infections.

Objective: This study aimed to investigate the relationship between procalcitonin (PCT) kinetic and estimated glomerular filtration rates (eGFR) in critically ill patients who had Gram-negative primary bloodstream infection (GN-BSI) and responded to the antimicrobial therapy.

Materials and methods: This single-centered study was retrospective and observational. Critically ill GN-BSI patients over 18 years old who had clinical and microbiological responses to antibiotic treatment were included in the study. Patients were divided into two groups according to eGFR (eGFR <30 mL/min/1.73m² and ≥30 mL/min/1.73m²) and compared for PCT kinetic at seven different measurement points as initial, first, third, fifth, seventh, tenth, and fourteenth days.

Results: The study included 138 patients. Initial PCT levels were higher in patients with eGFR <30 mL/min/1.73m² (4.58 [1.36-39.4] ng/mL) than in eGFR ≥30 mL/min/1.73m² (0.91 [0.32-10.2]) (p<0.001). This elevation was present at all measurement points (p<0.05). The decrease in PCT values by ≥30% (26.0% vs 47.9%; p=0.024) on the third day and ≥50% (69.2% vs 76.6%; p=0.411) on the fifth day was less in the low eGFR (<30 mL/min/1.73m²) group. The effect of low GFR on serum PCT kinetic was present in both fermenter and non-fermenter GN-BSIs but was more prominent in the fermenter group.

Conclusion: Serum PCT levels during therapy were higher in patients with low eGFR. Early PCT (<5 days) response was not obtained in non-fermenter GN-BSI patients with low eGFR. Antibiotic revision decisions should be made more carefully in patients with low eGFR due to high initial PCT levels and slow PCT kinetic.