Procalcitonin does discriminate between sepsis and systemic inflammatory response syndrome

Ronaldo Arkader ¹, Eduardo Juan Troster ¹, Marcel Rezende Lopes ¹, Roberto Raiz Júnior ¹, Joseph Carcillo ², Claudio Leoni ³ and Thelma Suely Okay ^1*

¹ University of São Paulo, Brazil
² University of Pittsburgh School of Medicine, United States
³ Hospital das Clínicas, Brazil

^* To whom correspondence should be addressed. E-mail: tsokay{at}icr.hcnet.usp.br.

Accepted 16 October 2005

Abstract

Objective: to evaluate whether procalcitonin (PCT) and C reactive protein (CRP) are able to discriminate between sepsis and systemic inflammatory response syndrome (SIRS) in critically ill pediatric patients.

Design and Setting: Prospective, observational study in a pediatric intensive care unit. The study was divided in two parts: I) kinetics of PCT and CRP in patients undergoing open heart surgery with cardiopulmonary bypass (CPB), representing the SIRS model (group I) [1]. II) Kinetics of PCT and CRP in patients with confirmed bacterial sepsis (group II).

Patients: Fourteen patients with confirmed bacterial sepsis (group II).

Measurements and main results: In group I PCT and CRP concentrations were determined in five different times: before CPB; immediately after CPB; 24h; 48h and 72h after the procedure. Although all 14 patients of group I had negative cultures, the sampling time "before CPB" was obtained in order to ensure that baseline laboratory markers were within reference values, but these results were not used in statistical analyses between groups. PCT median concentration was 0.24 ng/mL thus confirming that patients were not infected (reference value < 2.0 ng/mL). There was an increment of PCT concentrations which peaked immediately after CPB (median 0.58 ng/mL), then decreased to 0.47 ng/mL at 24 h; 0.33 ng/mL at 48h and 0.22 ng/mL at 72 h. CRP median concentrations remained high on POD1 (36.6 mg/L) and POD2 (13.0 mg/L). In septic children (group II), PCT and CRP were measured four times: at admission; 24 h, 48 h and 72 h after hospitalization. PCT concentrations were high at admission (median 9.15 ng/mL) and unlikely CRP, decreased afterwards in 11 of 14 patients who evolved favorably (median 0.31 ng/mL). Conversely, CRP levels were high in only 11 out of 14 patients at admission. CRP persisted high in 13 of 14 patients at 24 h; in 12 of 14 at 48 h; and finally in 10 of 14 patients at 72 h. Median values were: 95.0 mg/L; 50.9 mg/L 86.0 mg/L and 20.3 mg/L, respectively. The area under the receiver operating characteristic curve (ROC) was 0.99 for PCT and 0.54 for CRP. Cut off concentrations to differentiate SIRS from sepsis were > 2 ng/mL for PCT and > 79 mg/L for CRP.

Conclusion: PCT is able to differentiate between SIRS and sepsis. CRP lacked sensitivity as it did not detect 3 septic patients at admission. Moreover, CRP did not modulate according to patients outcome as did PCT. The latter returned to reference values in 11 of 14 patients who evolved favorably, persisting high in the 3 patients who died.

Keywords: C reactive protein, cardiopulmonary bypass, procalcitonin, sepsis, systemic inflammatory response syndrome

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