Difference In Procalcitonin Values Research Articles

Does Serial Procalcitonin Monitoring predict Clinical Outcomes in Children with Sepsis? A diagnostic stewardship study

Background: In the management of children with sepsis, inflammatory markers are often obtained upon admission and repeated frequently. It is unclear if serial monitoring of procalcitonin is useful for predicting patient outcomes. The focus of our study is to identify if the trend of procalcitonin levels was predictive of the clinical outcomes in children with sepsis. Methods: We performed a retrospective diagnostic study to evaluate the association between change in procalcitonin levels and clinical outcomes. Encounters for children 1 to 8 years old with a sepsis ICD 10 diagnosis code and meeting the clinical sepsis criteria from May 2020 to May 2022 at one quaternary care pediatric hospital were included. Encounters with fewer than two procalcitonin values and children with autoimmune diseases, trauma, new onset malignancy, and fungal infections were excluded. Procalcitonin clearance at 48 hours (CL-PCT48) was defined as the difference in procalcitonin values drawn on admission and at 48 hours divided by initial procalcitonin value. The primary outcome was good early clinical response, defined as composite measure of temperature, hemodynamic stability, supplemental oxygen requirement, and need for renal replacement therapy at 120 hours of admission. All-cause in-hospital mortality was a secondary outcome. ROC analysis was performed to measure the correlation of CL-PCT48 and initial procalcitonin value (PCT0) with the outcome. Result: There were 320 unique encounters for children who met the clinical criteria of sepsis. The median number of procalcitonin measurements was 4 (Range 2 – 111). Of these encounters, 187 had procalcitonin measurements done at eligible times. The mean age of the study participants was 9 years and 8 months, 103 (55%) were male, and the majority (54%) were Caucasian. Fifty-seven (30%) individuals had bacterial growth from a culture from sterile body fluid or urine. 78 (41.7%) individuals had good early clinical response and 177 (94.7%) survived to hospital discharge. There was no correlation identified between CL-PCT48 and good early clinical response (area under ROC curve [AUC] = 0.57, 95% CI 0.48-0.65, Figure 1) or mortality (AUC = 0.60, 95% CI 0.43-0.76, Figure 2). There was also no correlation between PCT0 and good early clinical response (AUC = 0.47, 95% CI 0.39-0.56) or and mortality (AUC = 0.50, 95% CI 0.29-0.72). Conclusion: Procalcitonin clearance at 48 hours after admission did not predict early clinical response in children with sepsis.

Effectiveness of nonsurgical antibiotic treatment in the experimental appendicitis model in rats

BackgroundIn this study, we aimed to demonstrate efficacy and laboratory follow-up criteria of nonsurgical antibiotic treatment in uncomplicated acute appendicitis. We established an experimental appendicitis model in rats, and antibiotic treatment was evaluated by biochemical and immunohistochemical changes.Materials and methodIn the study, 28 rats were divided into 4 groups. Group 1 constituted the group of sham; group 2 was the control group that appendicitis model was created and did not receive any treatment. Group 3 was created as an appendicitis model and was given regular antibiotic treatment. In group 4, appendicitis model was created, and appendectomy was performed on the 2nd day. Blood samples were taken from the rats on the 0, 2nd, and 7th days in all groups. Rats in groups 1, 2, and 3 underwent appendectomy with laparotomy under anesthesia on the 7th day. Serum C-reactive protein (CRP), procalcitonin, and leukocyte levels were measured for biochemical analysis. In immunohistochemical evaluation, inflammation severity of the tissue samples taken from appendices was evaluated. Also, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) levels of tissue samples were evaluated.ResultsA statistically significant difference in CRP values was observed between groups 1 and 2 on the 7th day (p = 0.046), between groups 1 and 4 on 0 and 2nd days (p = 0.004, p = 0.004), between groups 2 and 3 on 0, 2nd, and 7th days (p = 0.018, 0.013, 0.025), between groups 2 and 4 on 0, 2nd, and 7th days (p = 0.002, p = 0.002, p = 0.009), and between groups 3 and 4 on 0 and 2nd days (p = 0.013, p = 0.025). There was a significant difference in procalcitonin values between groups 1 and 3 on the 7th day (p = 0.032) and between groups 1 and 4 on day 0 (p = 0.019). A significant difference was also observed in TNF-α and IL-6 inflammation between groups 2 and 3 (p = 0.031, p = 0.018) and between groups 2 and 4 (p = 0.031, p = 0.01).ConclusionAcute uncomplicated and early appendicitis may be treated with antibiotics. According to our results, CRP levels are useful as follow-up criterion in experimental appendicitis model. Clinical studies on the assessment of CRP levels in the course of nonsurgical treatment in the patients with acute appendicitis will reveal out the effectiveness of this marker.

IBM WATSON Trauma Pathway Explorer© as a Predictor for Sepsis after Polytrauma - Is Procalcitonin Useful for Identifying Septic Polytrauma Patients?

IBM and the University Hospital Zurich have developed an online tool for predicting outcomes of a patient with polytrauma, the IBM WATSON Trauma Pathway Explorer® . The three predicted outcomes are Systemic Inflammatory Response Syndrome (SIRS) and sepsis within 21 days as well as early death within 72 hours since the admission of the patient. The validated Trauma Pathway Explorer® offers insights into the most common laboratory parameters, such as procalcitonin (PCT). Sepsis is one of the most important complications after polytrauma, which is why it is crucial to detect it early. This study aimed to examine the time-dependent relationship between PCT values and sepsis, based on the WATSON technology. A total of 3653 patients were included, and ongoing admissions are incorporated continuously. Patients were split into two groups (sepsis and non-sepsis), and the PCT value was assessed for 21 days (1, 2, 3, 4, 6, 8, 12, 24, 48 hours, and 3, 4, 5, 7, 10, 14 and 21 days). The Mann-Whitney U-Test was used to evaluate the difference between the two groups. Binary logistic regression was utilized to examine the dependency of prediction. The Closest Top-left Threshold Method provided time-specific thresholds at which the PCT level is predictive for sepsis. At p <0.05, the data were declared significant. R was used to conduct all statistical analyses. The Mann-Whitney U-test showed a significant difference in PCT values in sepsis and non-sepsis patients between 12 and 24 hours, including post-hoc analysis (p <0.05). Likewise, the p-value started to be significant between 12 and 24 hours in the binary logistic regression (p <0.05). The threshold value of PCT to predict sepsis at 24 hours is 0.7μg/l, and at 48 hours 0.5μg/l. The presented time course of PCT levels in polytrauma patients shows the PCT as a separate predictor for sepsis relatively early. Even later, during the 21-day observation period, time-dependent PCT values may be utilized as a benchmark for the early and preemptive detection of sepsis, which may reduce death from septic shock and other deadly infectious episodes.

Comparison of the Power of Procalcitonin and C-Reactive Protein to Differentiate between Different Etiologies of Febrile Neutropenia in Patients with Prolonged Profound Neutropenia

Background: The management of febrile neutropenia in case of prolonged profound neutropenia remains challenging as there are many possible infectious and non-infectious causes for fever in these patients. In more than 60% of cases there is no documented infectious etiology and unresolved febrile neutropenia often results in multiple empirical modifications of antibacterial therapy and/or addition of antifungal therapy. Unfortunately, indiscriminate use of broad-spectrum antibiotics can lead to important collateral damage including toxicity, selection of multidrug resistant pathogens and an increased predisposition to other infections such as Clostridium difficile or yeasts/fungi. In this study, we investigated whether procalcitonin (PCT) is superior to C-reactive protein (CRP) in discriminating between different etiologies of fever.Methods: CRP and PCT were tested daily during 93 neutropenic episodes in 66 patients (Table 1). A linear mixed model was performed to evaluate the effects of different variables on the values of CRP and PCT over time. A total of 121 febrile episodes occurred during this study period and were classified into four categories based on clinical and microbiological findings: microbiologically documented infection (MDI); clinically documented infection (CDI); proven or probable invasive fungal disease (IFD); fever of unknown origin (FUO). The values of PCT and CRP on day 2 after onset of fever were considered for analysis of their performance in distinguishing etiologies of fever in receiver operating characteristic (ROC) curves and by calculation of sensitivity, specificity, positive & negative predictive values and efficiency.Results: In 61 out of 93 neutropenic episodes (66.7%) the evolution of PCT and CRP was clearly different. CRP seemed to be a more volatile parameter, rising above its ULN (3 mg/dL) during every neutropenic episode. Its reactivity to stimuli was also quite pronounced with a median of 2 surges above 100 mg/dL per neutropenic episode. In contrast, PCT did not rise above its ULN (0.5 ng/mL) in 50 out of 93 neutropenic episodes (53.8%). The only confounding factor on the evolution of CRP and PCT with a clinically relevant large effect size was administration of antithymocyte globulin (ATG), which led to an 11-fold increase of PCT versus a 2-fold increase of CRP.On the day of fever onset no significant difference in PCT values was observed between different etiologies of fever (p=0.314), whereas median CRP values were significantly higher in IFD versus all other etiologies (median 98.8 mg/dL vs 28.8 mg/dL, p=0.027). Both PCT and CRP reached their peak at a median of 2 days after onset of febrile neutropenia. Median PCT values on day 2 showed no statistically significant difference when comparing etiologies of fever (Figure 1A). There was a tendency towards higher median PCT values in MDI and IFD where they rose > 0.25 ng/mL, while they did not in CDI or FUO without prior administration of ATG. Median CRP values on day 2 after fever onset were significantly higher in IFD versus all other etiologies (median 172 mg/dL vs 78.4 mg/dL, p=0.002). In MDI median CRP values rose > 100 mg/dL, whereas they did not in CDI or FUO (Figure 1B).The discriminatory power between IFD and FUO of CRP on day 2 after onset of febrile neutropenia was superior to that of PCT. With the cut-off set at 200 mg/dL, CRP has a positive predictive value of 66.7% and a negative predictive value of 97% for the diagnosis of IFD versus FUO, leading to an efficiency of 94.5%.Conclusions: Both CRP and PCT are not able to predict neither etiology nor severity of infection at the onset of fever. When performing reassessment of antibiotic therapy 2 days after onset of febrile neutropenia, CRP has the better discriminatory power between etiologies of fever and shows higher peak values in clinically severe infections. As such we conclude that PCT has no added value over CRP for clinical management of febrile neutropenia. In our study a CRP value above 200 mg/dL has a positive predictive value of 66.7% and a negative predictive value of 97% for the diagnosis of IFD versus FUO (when MDI and CDI were ruled out by diagnostic workup). A high CRP in the absence of a clear focus of infection might prompt earlier investigation for IFD, leading to earlier treatment initiation and lower mortality. In view of the low numbers of IFD in our study it is important to note that this finding should be confirmed in a larger patient population. [Display omitted] DisclosuresVerlinden:MSD - Merck: Research Funding. Gadisseur:Bayer: Research Funding.

Procalcitonin: the ideal predictor of anastomotic leakage. But, when?

Background: Rectal cancer ranks 3rd among the most common malignancies in both sexes. Abdominal infections that can be seen after rectal cancer surgery are the most feared postoperative complications, as they can also be the harbinger of anastomotic leakage. According to its localization, the rate of anastomotic leak varies between 4% and 29.5%. Procalcitonin (PCT) is an increasing parameter in bacterial infections and sepsis. Therefore, it is used to monitor the infection and the effectiveness of the treatment. Our study we aimed to evaluate the effect of PCT on early diagnosis of anastomotic leakage in rectal surgery and the correlation between PCT and CRP and WBC levels.Methods: File records of 50 patients who were operated on for rectal cancer and had anastomosis between 2016 and 2019 were retrospectively analyzed. Demographic features, operation information, preoperative and postoperative clinical features of the patients were recorded. The WBC, CRP and procalcitonin values of the patients were measured on the preoperative and postoperative 1st and 5th days. Patients were divided into two groups as PC values&lt;2 ng/ml and ≥2 ng/ml. Patients with surgical site infections were found. The relationship between hospital stay and PCT levels and those with surgical incision site infection and those with intra-abdominal infection was examined. The correlation between PCT values and CRP and WBC values of the patients was evaluated.Results: There was no significant difference in PCT values in infections at the surgical incision site. However, it was observed that the PCT values of patients with surgical infection in the abdomen were significantly higher than those without (p=0.005). It was observed that the PCT level was high and the duration of hospital stay was observed to be prolonged in patients with infections in the surgical incision area and in the abdomen.Conclusions: PCT can be used as a biochemical parameter in terms of abdominal infection and anastomotic leaks. It is recommended to be checked especially on the fifth postoperative day and to investigate for anastomotic leakage if it is seen to reach the highest value.

Comparison of the Power of Procalcitonin and C-Reactive Protein to Discriminate between Different Aetiologies of Fever in Prolonged Profound Neutropenia: A Single-Centre Prospective Observational Study.

Management of fever in prolonged, profound neutropenia remains challenging with many possible infectious and non-infectious causes. We investigated whether procalcitonin (PCT) is superior to C-reactive protein (CRP) in discriminating between different aetiologies of fever in this setting.CRP and PCT were tested daily during 93 neutropenic episodes in 66 patients. During this study period, 121 febrile episodes occurred and were classified into four categories based on clinical and microbiological findings: microbiologically documented infection (MDI); clinically documented infection (CDI); proven or probable invasive fungal disease (IFD); fever of unknown origin (FUO). Values of PCT and CRP at fever onset as well as two days later were considered for analysis of their performance in distinguishing aetiologies of fever.At fever onset, no significant difference in PCT values was observed between different aetiologies of fever, whereas median CRP values were significantly higher in case of IFD (median 98.8 mg/L vs 28.8 mg/L, p=0.027). Both PCT and CRP reached their peak at a median of 2 days after fever onset. Median PCT values on day 2 showed no significant difference between the aetiologies of fever. Median CRP values on day 2 were significantly higher in IFD (median 172 mg/L versus 78.4 mg/L, p=0.002). In MDI median CRP values rose > 100 mg/L, whereas they did not in CDI or FUO.PCT has no added value over CRP for clinical management of fever in prolonged, profound neutropenia. When performing reassessment 2 days after fever onset, CRP has better discriminatory power between aetiologies of fever.

Is there a role for procalcitonin in differentiating uncomplicated and complicated diverticulitis in order to reduce antibiotic therapy? A prospective diagnostic cohort study.

While studies show that antibiotic treatment for uncomplicated diverticulitis seems to have no benefit, most experts advocate antimicrobial therapy for complicated diverticulitis. However, even for uncomplicated diverticulitis, most clinicians are very reluctant to withhold antibiotics. Biomarkers could help to guide antibiotic therapy as this approach has been shown to be effective for acute respiratory infections. In this diagnostic cohort study we evaluated whether procalcitonin could be a biomarker to distinguish complicated from uncomplicated cases of diverticulitis. Complicated diverticulitis was defined as having abscess formation or perforation diagnosed by abdominal computed tomography (CT) scan. In all patients with suspected diverticulitis, procalcitonin values were measured at admission and on day 2. These values were blinded for clinicians, and treatment was carried out according to the physician's judgement. Two groups (complicated vs uncomplicated diverticulitis) were defined. Patients who had received antibiotic treatment before admission were excluded. Difference in procalcitonin values was calculated for both groups using the Mann-Whitney test. Receiver operating characteristics (ROC) were calculated to determine cut-off values for procalcitonin according to the gold standard (abdominal CT scans). 115 patients were included for analysis. 35 patients (30%) suffered from complicated diverticulitis. The median procalcitonin value for uncomplicated diverticulitis was significantly lower compared to complicated diverticulitis (median 0.05, interquartile range [IQR] 0.05-0.06 ng/l vs median 0.13, IQR 0.05-0.23 ng/l; p <0.0001). In the ROC analysis, the sensitivity and specificity were 81% and 91% when the highest procalcitonin value (days 1 and 2) was considered, with a cut-off value of 0.1 ng/l. Procalcitonin was able to differentiate with a high sensitivity and specificity between complicated and uncomplicated cases of diverticulitis when combined with abdominal CT scans. As most clinicians still treat uncomplicated diverticulitis with antibiotics, procalcitonin could be an interesting parameter for guiding therapy and decreasing antibiotic usage. This should be further evaluated in randomised trials.

Procalcitonin is a Poor Predictor of Non-Infectious Fever in the Neurocritical Care Unit.

Fever is a common occurrence in the Neurocritical Care Unit (NCCU). It is reported that up to 50% of these fevers are associated with a non-infectious source. As this is a diagnosis of exclusion, a complete fever evaluation must be done to rule out infection. Procalcitonin (PCT) has been identified as a possible biomarker to distinguish infectious from non-infectious etiologies of fever. We hypothesized that PCT could be used as a predictor of infectious fever in febrile patients with intracranial hemorrhage admitted to the NCCU. A prospective observational cohort of patients admitted to a 12-bed NCCU in a tertiary-care university hospital from January 1, 2014, to October 1, 2014, was studied. Patients with intracranial hemorrhage (aneurismal subarachnoid hemorrhage, traumatic brain injury, intracerebral hemorrhage, or non-traumatic subdural hemorrhage) and fever defined as ≥101.4°F were included. All patients had a urinalysis, chest X-ray, two sets of blood cultures, and PCT as part of their fever evaluation. Patients also had urine, sputum, CSF cultures, and Clostridium difficile toxin PCR as clinically indicated. Patients with incomplete fever evaluations were excluded. Seventy-three patients met inclusion criteria: 36 had infections identified and 37 did not. Type of intracranial hemorrhage was similar between groups. For those with identified infection, median PCT was 0.15ng/mL (IQR 0.06-0.5ng/mL). For those without identified infection, median PCT was 0.09ng/mL (IQR 0.05-0.45ng/mL), p=0.30. Analyzing subgroups of intracranial hemorrhage patients revealed no group with a significant difference in PCT values. Patients with identified infection did have higher white blood cell counts (median 14.1×109/L (11.6-17.4×109/L) compared to those without identified infection 12×109/L (9.9-14.1×109/L), p=0.02. Among patients with intracranial hemorrhage, PCT did not differentiate infectious fever from non-infectious fever.

Procalcitonin Dynamics After Long-Term Ventricular Assist Device Implantation.

Infectious complications (IC) are one of the main causes of worsening prognosis after long-term ventricular assist device (LVAD) implantation. Procalcitonin (PCT) is widely used for diagnosis of a bacterial infection. The objective of this study was to assess PCT dynamics after LVAD surgery and their relationship to the infectious complications. A total of 25 consecutive patients indicated for LVAD implantation as a bridge to heart transplant were included. Procalcitonin levels were prospectively assessed before surgery and during the postoperative period (day 1, 2, 14 and 30). Values were compared according to the presence of IC. Procalcitonin levels were low before surgery, raised significantly within 1st and 2nd day after operation and decreased in the 14th and 30th days back to the baseline. There was no significant difference in PCT values between patients with or without IC as well as with or without right ventricle assist device (RVAD). Acute renal failure (ARF) increased PCT significantly only 14 days after LVAD implantation. In patients with ARF and/or RVAD we observed significantly higher PCT values in the 2nd, 14th and 30th day after operation. In subjects with IC and/or ARF and/or RVAD we also observed significantly elevated PCT concentrations 2 and 14 days after surgery. Our data show that the ability of PCT to detect IC in patients after LVAD implantation is limited and its concentrations more likely correlate with postoperative complications in general.

Procalcitonin is more likely to be released by the fetus rather than placental tissue during chorioamnionitis.

To analyze the relationship between maternal, cord blood and neonatal procalcitonin (PCT) levels in preterm deliveries with and without histologically proven chorioamnionitis (HCA). 91 mother-infant pairs from 24+0 to 33+0 gestational weeks were analyzed. Procalcitonin was measured in all mothers within 24 hours before and subsequently in cord blood and in neonates within the first two hours after delivery. PCT levels were analysed in relationship to HCA and clinical outcome. HCA was confirmed in 28 cases (31%). We found no differences in PCT values between HCA positive and negative groups in maternal blood (0.1±0.1 vs 0.09±0.09 ng/L, P = 0.76). PCT values in cord blood and neonates were significantly higher in the HCA positive compared to HCA negative group (0.23±0.1 vs 1.2±2.7 ng/L, P < 0.001 and 0.89±3.4 vs 4.2±9.3 ng/L, P < 0.0001 respectively). PCT values in neonates were significantly higher than those of cord blood. Levels were not influenced by the mode of delivery, gestational age or premature rupture of membranes. Chorioamnionitis was more frequently associated with early onset neonatal sepsis (36% in HCA group vs 5% in non HCA group, P < 0.0001). Comparison of other clinical data revealed no differences between HCA positive and negative groups. This study showed higher PCT in cord and neonatal blood in the presence of proven histological chorioamnionitis. The measurement of PCT in mothers' blood is not helpful for diagnosis of HCA. The changes in PCT values shown suggest its production and release by fetal tissue.

SUN-PP061: Gut Dysfunction in Abdominal Compartment Syndrome during Severe Acute Pancreatitis and Dilemmas in Nutritional Support

Rationale: Enteral nutrition (EN) is a gold standard for the patients with severe acute pancreatitis (SAP), but in those with abdominal compartment syndrome (ACS) can aggravate bowel ischaemia. Total parenteral nutrition (TPN) may increase bacterial translocation and deteriorate gut functions. Methods: Study included 36 patients with SAP (21 with ACS and 15 without). Intra-abdominal pressure (IAP) was measured daily and maximal noted IAP (maxIAP) during hospitalization was included in the study. In each patient a serum level of procalcitonin (PCT) was measured daily. A value of PCT at 48 h on hospital admission and maximal noted PCT (maxPCT) during hospitalization were included. Nutritional support was EN, TPN or EN+TPN in the same time. Results: MaxIAP in patients with ACS was significant higher than in those without (p < 0.001). There were no difference in PCT values between patients with and without ACS (p = 0.64). MaxPCT in patients with ACS was 3.1 ng/mL (1.3 34.6) and in those without ACS was 2.3 ng/mL (0.4 12), (p = 0.03). In patients who received TPN 20 (95%) had ACS and 8 (53%) had not (p = 0.005). In patients who received EN 12 (57%) had ACS and 15 (100%) had not (p = 0.005). In patients who received EN+TPN in the same time 11 (52%) had ACS and 8 (53%) had not (p = 1). In patients who received TPN a significant higher PCT (p = 0.01) and maxPCT values (p < 0.001) were noted than in those who did not. In patients who received EN there was no difference in value of PCT (p = 0.06), but significant higher maxPCT value was found in patients who received EN than in those who did not (p = 0.04). No difference in PCT and maxPCT values were found in patients who received EN+TPN in the same time than in those who did not (p = 0.68, p = 0.29). Conclusion: In ACS during SAP serum values of PCT are higher in patients on TPN. Balanced usage of EN+TPN has a less influence on gut functioning than EN or TPN alone in patients with ACS and SAP.

Use of procalcitonin for the differential diagnosis of fever in cancer patients: an observational study

Fever often occurs in cancer patients and the possibility of having a reliable marker for the differential etiological diagnosis is desirable. The aim of this study was to investigate the eligibility of the use of procalcitonin (PCT) in hemato-oncological patients for the differential diagnosis of fever. We prospectively enrolled 98 cancer patients and divided them into two groups: those with active disease and those with non-active disease. Procalcitonin was dosed at Time 0 (recruitment) and at the onset of fever. On enrollment, PCT values were 0.1 ng/mL in 83% patients with active disease, and lower than 0.5 ng/mL in 23%, which is usually considered not suggestive of bacterial infection. Four percent of patients had values over 0.5 ng/mL and these were mainly patients with neuroendocrine tumors or affiliates. On enrollment, there were also no statistically significant differences in PCT values between the two groups of patients. This showed that active cancer is unable by itself to change PCT levels. In the active disease group, 21 episodes of fever due to bacterial infection were registered, and in all of them an increase in PCT values was observed. This demonstrates the ability of PCT to detect an infection-induced fever in cancer patients. Procalcitonin concentrations are not significantly altered by active neoplastic disease. On the contrary, in the course of fever due to a bacterial infection, PCT values increase and can, therefore, be considered a useful tool in the differential diagnosis between infection-induced fever and drug-related or tumor associated-fever. Procalcitonin may be a useful marker of bacterial infection even in cancer patients.

Longitudinal changes in procalcitonin in a heterogeneous group of critically ill patients*

The utility of procalcitonin for the diagnosis of infection in the critical care setting has been extensively investigated with conflicting results. Herein, we report procalcitonin values relative to baseline patient characteristics, presence of shock, intensive care unit time course, infectious status, and Gram stain of infecting organism. Prospective, multicenter, observational study of critically ill patients admitted to intensive care unit for >24 hrs. Three tertiary care intensive care units. All consenting patients admitted to three mixed medical-surgical intensive care units. Patients who had elective surgery, overdoses, and who were expected to stay <24 hrs were excluded. Patients were followed prospectively to ascertain the presence of prevalent (present at admission) or incident (developed during admission) infections and clinical outcomes. Procalcitonin levels were measured daily for 10 days and were analyzed as a function of the underlying patient characteristics, presence of shock, time of infection, and pathogen isolated. Five hundred ninety-eight patients were enrolled. Medical and surgical infected cohorts had similar baseline procalcitonin values (3.0 [0.7-15.3] vs. 3.7 [0.6-9.8], p=.68) and peak procalcitonin (4.5 [1.0-22.9] vs. 5.0 [0.9-16.0], p=.91). Infected patients were sicker than their noninfected counterparts (Acute Physiology and Chronic Health Evaluation II 22.9 vs. 19.3, p<.001); those with infection at admission had a trend toward higher peak procalcitonin values than did those whose infection developed in the intensive care unit (4.9 vs. 1.4, p=.06). The presence of shock was significantly associated with elevations in procalcitonin in cohorts who were and were not infected (both groups p<.003 on days 1-5). Procalcitonin dynamics were similar between surgical and medical cohorts. Shock had an association with higher procalcitonin values independent of the presence of infection. Trends in differences in procalcitonin values were seen in patients who had incident vs. prevalent infections.