Procalcitonin levels in peritoneal dialysis patients.

Objective: To examine whether the levels of procalcitonin (PCT), a new marker of infection and/or inflammation, differ between peritoneal dialysis (PD) patients and healthy volunteers, and whether PCT is detectable in uninfected drained dialysate.

Design: Observational cross-sectional study.

Setting: PD unit, department of medicine, in a university hospital.

Patients: A total of 28 PD patients, free of systemic infection, and 28 age- and sex-matched healthy volunteers.

Methods: PCT was determined by immunoluminometry; detection range 0.01 - 500 ng/mL, reference range < 0.5 ng/mL.

Results: Plasma levels of PCT were significantly higher (Wilcoxon's paired test, p < 0.001) in PD patients (median 0.33 ng/mL) compared with healthy volunteers (0.18 ng/mL). Spearman's test demonstrated a significant positive correlation between PCT and serum C-reactive protein (CRP) (r = 0.59, p < 0.01); correlations between PCT and transferrin, total weekly creatinine clearance (ClCr), and the renal components of ClCr and Kt/V urea were negative. PCT levels in dialysate (PCTd) were 0.07 ng/mL and correlated positively with plasma PCT, serum CRP, and dialysate fibrinogen levels. The dialysate-to-plasma ratio (D/P) of PCT was 0.2. Neither PCTd nor D/P PCT correlated with D/P creatinine at 4-hours of dwell.

Conclusion: Compared with healthy volunteers, PD patients without overt signs of infection showed increased plasma PCT levels. Given the study design, it is impossible to determine to what extent the increase in plasma PCT is due to reduced elimination and to what extent it reflects the microinflammation of uremia. Based on the D/P PCT gradient, we assume that PCT transport is more likely to occur from the systemic circulation to the peritoneal cavity than vice versa.