Cutoff value of serum procalcitonin as a diagnostic biomarker of infection in end-stage renal disease patients

Background/Aims: Serum procalcitonin (PCT) levels are low in healthy individuals but are elevated in patients with a serious bacterial infection or sepsis. In this study, we examined the ability of serum PCT concentration to diagnose infections in end-stage renal disease (ESRD) patients, and sought to determine an appropriate threshold level. Methods: Serum PCT levels were measured in ESRD patients on antibiotic therapy for a suspected bacterial infection (ESRD infection [iESRD] group, n = 21), and compared with those of ESRD patients on hemodialysis with no sign of infection (ESRD control [cESRD] group, n = 20). Results: The mean serum PCT concentration of the iESRD group was significantly higher than in the cESRD group ($2.95{\pm}3.67ng/mL$ vs. $0.50{\pm}0.49ng/mL$, p = 0.006), but serum PCT concentrations did not correlate with severity of infection. The optimized threshold level derived for serum PCT was 0.75 ng/mL, rather than the currently used 0.5 ng/mL; this threshold demonstrated a sensitivity and specificity of 76.2% and 80.0% for infection and 100% and 60.6% for systemic inflammatory response syndrome, respectively, compared with the cutoff of 0.5 ng/mL. Conclusions: This study suggests that serum PCT at a cutoff value of 0.75 ng/mL is an appropriate indicator of infection in ESRD patients.