Mortality is increased by procalcitonin and decreased by an antiserum reactive to procalcitonin in experimental sepsis

Kinetics of procalcitonin, interleukin 6 and C-reactive protein after cardiopulmonary-bypass in children

Cardiopulmonary bypass induces a generalized inflammatory response, with fever and leukocytes, which is difficult to differentiate from an infection. Recently, procalcitonin has been proposed as an early and specific marker of bacterial infection. The influence of cardiopulmonary bypass on production of procalcitonin, therefore, must be assessed before considering this molecule as a valuable marker of infection after cardiac surgery in children. With this in mind, we measured levels of procalcitonin, interleukin 6, and C-reactive protein before and 6h, 1, 3 and 5 days after cardiopulmonary bypass, in 25 children undergoing cardiac surgery. Cardiopulmonary-bypass induced a transient increase in procalcitonin, with a peak at 24 h, with a median of 1.13 microg/l, a 25th and 75th interquartile of 0.68-2.25, and a p value of less than 0.001. The value had returned to normal in the majority of the children by the third day after surgery. Peak values correlated with the duration of cardiopulmonary-bypass, with a r-value of 0.58 and a p value of 0.003; cross-clamp time, with a r-value of 0.62 and a p value of 0.001; days of mechanical ventilation, with a r-value of 0.62 and a p value of 0.001; and days of stay in intensive care, with a r-value of 0.68, and a p value of 0.0003. The value returned to normal after 3 days in 83% of the patients. Levels of interleukin 6 and C-reactive protein also increased significantly after surgery, and remained elevated for up to 5 days. Thus, in contrast to other markers, levels of procalcitonin in the serum are only slightly and transiently influenced by cardiopulmonary bypass, and may prove to be useful in the early recognition of an infection subsequent to cardiopulmonary bypass.

Procalcitonin as a diagnostic test for sepsis: health technology assessment in the ICU

Elevation in the serum concentration of procalcitonin (PCT) is associated with systemic infection. This association has led to the proposed use of PCT as a novel biomarker of bacterial sepsis. The advantages and limitations of the American College of Chest Physicians/Society of Critical Care Medicine (ACCP/SCCM) definitions of sepsis are an important consideration that affects the impact of any diagnostic test for sepsis and these issues are discussed. Our main objective is to perform a systematic health technology assessment of PCT as a diagnostic test for sepsis. In an adult intensive care unit (ICU) population, we identify a specific and important question-can PCT accurately distinguish sepsis in patients with systemic inflammatory response syndrome (SIRS) who have a suspected infection? Likelihood ratios are calculated from published data to attempt to find the best answer. The published evidence does not support a general claim that PCT is a useful decision support tool for diagnosing sepsis in patients who have SIRS. Procalcitonin has a slightly better ability to exclude the diagnosis of sepsis. The role for using PCT testing in the ICU will continue to evolve along with our understanding and definition of sepsis.

Calcitonin precursors in the prediction of severity of acute pancreatitis on the day of admission

BACKGROUND

Calcitonin precursors are sensitive markers of inflammation and infection. The aim of this study was to evaluate the role of plasma calcitonin precursor levels on the day of admission in the prediction of severity of acute pancreatitis, and to compare this with the Acute Physiology And Chronic Health Evaluation (APACHE) II scoring system.

METHODS

Plasma concentrations of calcitonin precursors were determined on admission in 69 patients with acute pancreatitis. APACHE II scores were calculated on admission. Attacks were classified as mild (n = 55) or severe (n = 14) according to the Atlanta criteria. Plasma calcitonin precursor levels were determined with a sensitive radioimmunoassay.

RESULTS

On the day of hospital admission, plasma levels of calcitonin precursors were significantly greater in patients with a severe attack compared with levels in those with a mild attack of pancreatitis (median 64 versus 25 fmol/ml; P = 0.014), but the APACHE II scores were no different (median 9 versus 8; P = 0.2). The sensitivity, specificity, positive predictive and negative predictive values, and accuracy for the prediction of severe acute pancreatitis were 67, 89, 57, 93 and 85 per cent respectively for plasma calcitonin precursor levels higher than 48 fmol/ml, and 69, 45, 23, 86 and 50 per cent respectively for an APACHE II score greater than 7. Differences in the specificity and accuracy of the two prognostic indicators were significant (P < 0.001 and P = 0.001 respectively). A plasma calcitonin precursor concentration of more than 160 fmol/ml on admission was highly accurate (94 per cent) in predicting the development of septic complications and death.

CONCLUSION

The assay of plasma calcitonin precursors on the day of admission to hospital has the potential to provide a more accurate prediction of the severity of acute pancreatitis than the APACHE II scoring system.

Procalciton: A new marker and mediator of systemic inflammatory response of the host to infection

<zakljucak> Prokalcitonin je medijator generalizovane reakcije domacina na infekciju, koji poseduje znacajan imunomodulatorni efekat. Indukcija PCT i porast njegovog nivoa u plazmi povezani su sa ekstenzivnoscu i tipom sistemske inflamacije, a njegova koncentracija se naglo smanjuje posle saniranja inflamacije. Kod bolesnika sa sepsom PCT je odlican dijagnosticki i prognosticki marker i veoma dobar parametar za procenu uspeha terapijskog tretmana i klinickog toka septickog procesa. Rutinsko odredjivanje njegove koncentracije u krvi moze popraviti laboratorijsko pracenje bolesnika sa sepsom.

Procalcitonin is persistently increased among children with poor outcome from bacterial sepsis

OBJECTIVE

To examine the relationships between procalcitonin, bacterial infection, sepsis-induced multiple organ failure, and mortality rate in children.

DESIGN

Cohort study.

SETTING

A multidisciplinary, tertiary-care pediatric intensive care unit.

PATIENTS

Seventy-eight children meeting criteria for sepsis or septic shock and 12 critically ill children without sepsis.

INTERVENTIONS

Venous or arterial blood sampling.

MEASUREMENTS AND MAIN RESULTS

Demographic, epidemiologic, and outcome data were recorded. Plasma from children with sepsis were collected on days 1 and 3, and procalcitonin concentrations were measured by immunoluminometric assay. Organ failure index scores were determined, and multiple organ failure was defined as organ failure index > or = 3. Persistent multiple organ failure was defined by presence of multiple organ failure on day 3. Procalcitonin concentrations (median [25th percentile-75th percentile]) were increased among children with sepsis on day 1 (2.4 ng/mL [0.2-24.2], p < .01) but not on day 3 (0.8 ng/mL [0.1-8.1], p = nonsignificant) vs. controls (0.2 ng/mL [0.1-0.5]). This increase in procalcitonin concentration was particularly robust among children with bacterial sepsis on day 1 (7.1 ng/mL [0.9-44.8], p < .001) and on day 3 (2.9 ng/mL [0.1-32.4], p < .05). Procalcitonin concentrations were not increased among children with fungal, viral, or culture-negative sepsis vs. controls. Procalcitonin concentrations were persistently increased over time among patients with bacterial sepsis who had persistent multiple organ failure (p < .05) and who died (p < .01) but not among patients with nonbacterial sepsis.

CONCLUSIONS

Procalcitonin is persistently increased among children with poor outcome from bacterial sepsis. Further study is needed to better delineate this differential procalcitonin response to bacterial vs. nonbacterial sepsis and to characterize any mechanistic role that procalcitonin might play in the development of bacterial sepsis-induced multiple organ failure and mortality.

Flow cytometric analysis of procalcitonin expression in human monocytes and granulocytes

Procalcitonin (PCT), a precursor of calcitonin is a useful indicator of severe systemic infection and sepsis. For a better understanding of the pathophysiological background of PCT induction, a study was made of the intracellular expression of PCT in various human white blood cell populations-i.e. monocytes and polymorphonuclear granulocytes (PMNs)-and the role of TNF-alpha in the stimulation of their PCT production. The expression of PCT was investigated by flow cytometric analysis with intracellular staining with antibodies to the PCT components calcitonin (CT) and katacalcin (KC). Both human peripheral monocytes and granulocytes expressed PCT, and increased intracellular amounts of the PCT components were demonstrated after stimulation with Staphylococcus aureus as TNF-alpha inducer. The S. aureus induced stimulation of PCT production was inhibited by anti-TNF-alpha monoclonal antibodies. The monocytic cell line U937 expressed considerable intracellular PCT, but S. aureus failed to induce an increase in PCT expression. The determination of intracellular PCT by flow cytometry is a promising and a sensitive method for further investigation of the effects of various cytokines and cytokine-inducing agents in PCT synthesis of human monocytes and granulocytes.

Reliability of procalcitonin as a severity marker in critically ill patients with inflammatory response

Procalcitonin (PCT) is increasingly recognised as an important diagnostic parameter in clinical evaluation of the critically ill. This prospective study was designed to investigate PCT as a diagnostic marker of infection in critically ill patients with sepsis. Eighty-five adult ICU patients were studied. Four groups were defined on the basis of clinical, laboratory and bacteriologic findings as systemic inflammatory response syndrome (SIRS) (n = 10), sepsis (n = 16), severe sepsis (n = 18) and septic shock (n = 41). Data were collected including C-reactive protein (CRP), PCT levels and Sequential Organ Failure Assessment and Acute Physiology and Chronic Health Evaluation II scores on each ICU day. PCT levels were significantly higher in patients with severe sepsis and septic shock (19.25 +/- 43.08 and 37.15 +/- 61.39 ng/ml) than patients with SIRS (0.73 +/- 1.37 ng/ml) (P < 0.05 for each comparison). As compared with SIRS patients, plasma PCT levels were significantly higher in infected patients (21.9 +/- 47.8 ng/ml), regardless of the degree of sepsis (P < 0.001). PCT showed a higher sensitivity (73% versus 35%) and specificity (83% versus 42%) compared to CRP in identifying infection as a cause of the inflammatory response. Best cut-off levels were 1.31 ng/ml for PCT and 13.9 mg/dl for CRP. We suggest that PCT is a more reliable marker than CRP in defining infection as a cause of systemic inflammatory response.

Early immunoneutralization of calcitonin precursors attenuates the adverse physiologic response to sepsis in pigs

OBJECTIVE

The 116 amino acid prohormone procalcitonin and some of its component peptides (collectively termed calcitonin precursors) are important markers and mediators of sepsis. In this study, we sought to evaluate the effect of immunoneutralization of calcitonin precursors on metabolic and physiologic variables of sepsis in a porcine model.

DESIGN

A prospective, controlled animal study.

SETTING

A university research laboratory.

SUBJECTS

30-kg Yorkshire pigs.

INTERVENTIONS

Sepsis was induced in 15 pigs by intraperitoneal instillation of a suspension of cecal content (1 g/kg animal body weight) and a toxinogenic Escherichia coli solution (2 x 10(11) colony-forming units). During induction of sepsis, seven pigs received an intravenous infusion of purified rabbit antiserum, reactive to the aminoterminal portion of porcine prohormone procalcitonin. Another eight control pigs received an intravenous infusion of purified nonreactive rabbit antiserum. For all 15 animals, physiologic data (urine output, core temperature, arterial pressure, heart rate, cardiac index, and stroke volume index) and metabolic data (serum blood urea nitrogen and creatinine, arterial lactate, and pH) were collected or recorded hourly until death at 15 hrs.

MEASUREMENTS AND MAIN RESULTS

In this large-animal model of rapidly lethal peritonitis, serum calcitonin precursors were significantly elevated. Amino-prohormone procalcitonin-reactive antiserum administration resulted in a significant improvement or a beneficial trend in a majority of the measured physiologic and metabolic derangements induced by sepsis. Specifically, arterial pressure, cardiac index, stroke volume index, pH, and creatinine were all significantly improved, while urine output and serum lactate had beneficial trends. Treated animals also experienced a statistically significant increase of short-term survival.

CONCLUSIONS

These data from a large-animal model with polymicrobial sepsis demonstrate the salutary effect of early immunoneutralization of calcitonin precursors on physiologic and metabolic variables. Immunologic blockade of calcitonin precursors may offer a novel therapeutic approach to human sepsis.

Procalcitonin amplifies inducible nitric oxide synthase gene expression and nitric oxide production in vascular smooth muscle cells

OBJECTIVE

Elevated procalcitonin concentrations are found in the course of systemic inflammation caused by bacterial insults, for example, sepsis and septic shock. However, the source of procalcitonin and its role in the inflammatory process are still unknown. In clinical studies, procalcitonin concentrations reflected the severity of sepsis and were predictive of mortality, suggesting that an increased procalcitonin synthesis is detrimental for the host. In contrast, and data report anti-inflammatory effects of procalcitonin that rather may represent a benefit for the septic patient.

DESIGN

Prospective, controlled, cell culture study.

SETTING

University research laboratories.

SUBJECTS

WKY rats.

INTERVENTIONS

We investigated whether procalcitonin affects one principal mediator of sepsis, inducible nitric oxide synthase-derived nitric oxide, taking into account the typical 3-hr delay of procalcitonin increase following a bacterial challenge. Vascular smooth muscle cells were incubated with lipopolysaccharide (10 microg/mL), tumor necrosis factor-alpha (500 units/mL), interferon-gamma (100 units/mL), and procalcitonin (1, 10, 100, and 1000 ng/mL). Cells were preincubated with lipopolysaccharide for 90 mins followed by the addition of tumor necrosis factor-alpha/interferon-gamma. In a second set of experiments, procalcitonin was added to these proinflammatory agonists 3 hrs after lipopolysaccharide application.

MEASUREMENTS AND MAIN RESULTS

Although no inducible nitric oxide synthase complementary DNA was detectable in unstimulated controls and following single application of procalcitonin, inducible nitric oxide synthase gene expression was induced in cells treated with lipopolysaccharide plus tumor necrosis factor-alpha/interferon-gamma for a total incubation time of 24 hrs. When vascular smooth muscle cells were incubated with procalcitonin in addition to lipopolysaccharide plus tumor necrosis factor-alpha/interferon-gamma, a further stimulation of inducible nitric oxide synthase transcription rate could be detected.

CONCLUSIONS

These results provide evidence that procalcitonin acts as a modulator that augments the inflammatory response triggered by agonists like lipopolysaccharide, tumor necrosis factor-alpha, and interferon-gamma. Although not effective as a single stimulus, it might contribute to the detrimental outcome following excessive activation of the inflammatory cascade.

Pathobiochemistry and clinical use of procalcitonin

Induction of the protein procalcitonin during infection and inflammation was first described approximately 10 years ago. A large number of publications, primarily clinical studies, demonstrate the increasing use of procalcitonin in modern clinical practice. However, data on the biological function and origin of procalcitonin is scarce. Findings regarding the possible role and source of procalcitonin in sepsis and infection were recently published, and the pathophysiology of the protein has meanwhile been investigated in various experimental models. Procalcitonin obviously has certain biological functions, and it is also known to be specifically induced. Given the hormonal origin of the mature protein and the inflammation-related functions of its propeptides, some investigators suggest that procalcitonin should be referred to as a "hormokine," although its biological functions should be studied in more detail. This review will survey the data now available in recent publications on the induction, production sources, possible biological functions and clinical uses of procalcitonin.

Procalcitonin as a marker of sepsis

Prompt diagnosis and treatment with appropriate antimicrobial chemotherapy is of paramount importance to reduce morbidity and mortality associated with sepsis. Inflammatory markers currently in use, such as C-reactive protein (CRP) do not reliably differentiate between the systemic inflammatory response and sepsis. Procalcitonin (PCT), a precursor of calcitonin, is a 116 amino acid protein that has been proposed as a marker of disease severity in conditions such as septicaemia, meningitis, pneumonia, urinary tract infection (UTI) and fungal and parasitic infection. In particular, serial measurements are useful in order to monitor response to therapy. Together with good clinical judgement and judicious use of antimicrobial agents, PCT should serve as a valuable adjunct in the diagnosis and management of sepsis.

Procalcitonin and proinflammatory cytokine clearance during continuous venovenous haemofiltration in septic patients

Procalcitonin (PCT), interleukin-6 (IL-6), tumour necrosis factor a (TNFalpha), and interleukin-1beta (IL-1beta) are important clinical prognostic markers in ICU septic patients. The goal of the study was to determine whether continuous venovenous haemofiltration (CWH), using an AN69 haemofilte, leads to elimination of PCT, TNFalpha, IL-6 and IL-1beta in 13 septic patients with multi-organ failure. At the start of haemofiltration (0), 6 and 12 hours the mean afferent plasma concentration +/- SD of PCT (10.1 +/- 9.1, 7 +/- 6, 5.9 +/- 5.7 ng/ml), IL-6 (804.6 +/- 847.6, 611.7 +/- 528.4, 575.2 +/- 539.2 pg/ml), and that of TNFalpha (4.5 +/- 2.6, 4 +/- 3.1, 3.8 +/- 2.9 pg/ml) significantly declined during CVVH. The efferent plasma concentrations were significantly lower than the corresponding afferent concentrations. PCT; IL-6 and TNFalpha were detectable in the ultrafiltrate of all patients. IL-1beta was only detectable in the plasma of eight patients and the ultrafiltrate of five patients. The plasma clearance of PCT, IL-6 and TNFalpha significantly decreased after 12 hours as a result of a decline in the adsorptive elimination of the mediators due to progressive membrane saturation. We demonstrated that if PCT, IL-6 and TNFalpha are used as clinical prognostic markers in septic patients who are treated with CWIH using an AN69 membrane, one should be aware that their plasma level could be modified by the therapy. In addition CWH could represent an appropriate tool to remove a broad spectrum of proinflammatory mediators, if such removal is required in septic patients.

Calcitonin gene expression induced by lipopolysaccharide in the rat pituitary

Procalcitonin (PCT), the precursor protein of calcitonin (CT), has been considered recently as a significant indicator of bacterial infection and sepsis. However, the major source of PCT in sepsis remains unclear. The hypothalamic-pituitary-adrenal axis is activated during sepsis. Moreover, immunoreactive CT (iCT) can be detected in the pituitary. Therefore, we examined the effects of lipopolysaccharide (LPS) administration on CT mRNA expression in the pituitary. After administration of LPS, CT mRNA expression in the pituitary was increased significantly. The increase of CT mRNA was associated with significant elevations of the iCT levels in the serum. These results imply that the pituitary is one of the sources of the serum PCT during sepsis.

Plasma procalcitonin and C-reactive protein in acute septic shock: clinical and biological correlates

OBJECTIVE

To determine the relationship between plasma procalcitonin (PCT) levels, C-reactive protein (CRP), white blood cell count (WBC), ionized calcium (Ca2+), and patient outcome; and to compare the diagnostic and prognostic information provided by PCT and by CRP.

DESIGN

Prospective, observational study.

SETTING

Intensive care unit.

PATIENTS

Fifty-three patients with septic shock, consecutively diagnosed according to consensus guidelines.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood was sampled at diagnosis and 24 and 48 hrs later and in a subgroup (n = 23) after 120 hrs. PCT was measured with LUMItest and CRP with Vitros slides. Ca2+ was calculated according to McLean-Hastings from calcium and protein levels on Vitros. In all 53 patients, PCT and CRP were elevated (>0.5 ng/mL and >10 mg/L, respectively) within 24 hrs after diagnosis. Nonsurvivors (n = 25) were older (p <.001) and had higher Acute Physiology and Chronic Health Evaluation (APACHE) II scores (p =.02) at diagnosis but did not differ in sepsis etiology, medical history, sex ratio, levels of PCT, CRP, and Ca2+, or WBC count at any time point. Using logistic regression, initial PCT levels were correlated with CRP values (p =.001) and APACHE II score (p <.05), but not with age, gender, Ca2+ levels, survival, or type of pathogen. Within 48 hrs, however, PCT levels decreased more frequently from baseline in survivors than in nonsurvivors (80% vs. 41%, p <.05). Likewise, CRP levels decreased more often in survivors (100% vs. 64%, p <.05) but only at 120 hrs.

CONCLUSIONS

PCT levels were correlated with the severity of disease at onset (APACHE II) and inflammation (CRP) but not with Ca2+ levels. Inaugural PCT or CRP levels per se poorly predicted outcome but decreasing levels were associated with a higher probability of survival. In this respect, PCT was found to be an earlier marker than CRP.

Procalcitonin, C-reactive protein and APACHE II score for risk evaluation in patients with severe pneumonia

OBJECTIVE

Procalcitonin (PCT) is a peptide that is found elevated in patients with sepsis and severe infections. In healthy persons PCT serum levels are below 0.1 ng/mL. The aim of this study was to investigate the value of serum PCT determination for risk evaluation in patients with pneumonia.

METHODS

We focused on the correlation of PCT with the clinical status of the patient and prognosis of the disease. In a prospective study, in a nonsurgical intensive care unit the following parameters were assessed regularly in 93 patients with documented pneumonia: C-reactive protein (CRP), white blood cell count (WBC), body temperature, PCT and Acute Physiology and Chronic Health Evaluation (APACHE) II score.

RESULTS

At the onset of infection 50% of the patients had elevated PCT levels above 2 ng/mL. The model of multivariate analysis of all tested parameters on days 0-5 stratified for clinical outcome (change in clinical classification or death) showed local significance for APACHE II score only. None of the other parameters in this model serves as an isolated indicator for change of clinical status or death. An intra-individual change of body temperature or CRP was never significantly associated with a change in the clinical status of the patient.

CONCLUSION

Change in PCT on admission and at the end of the observation period significantly indicated a clinical change.

Low sensitivity of serum procalcitonin in bacterial meningitis in adults

Several studies have suggested high predictive values of serum procalcitonin (PCT) for the discrimination of bacterial and viral meningitis in children and adults. Here, we report PCT serum concentrations in 12 adults suffering from bacterial meningitis. PCT on admission was normal ( < or = 500 pg/ml) in 3 and between 500 and 1,000 pg/ml in 2 patients without evidence of concurrent bacterial infections. Conversely, in 5 patients with PCT concentrations between 2,268 and 38,246 pg/ml other infections were present. PCT concentrations were higher with typical meningitis agents (pneumococci and meningococci 12,679 +/- 13,092 pg/ml vs. other bacteria 4048 +/- 9187 pg/ml, p = 0.041) whilst in nosocomial bacterial meningitis after neurosurgery (n = 3) serum PCT remained normal. We believe that PCT is of limited diagnostic value in adults suffering from bacterial meningitis, especially in cases due to unusual agents or of nosocomial origin. Elevated PCT in bacterial meningitis may indicate the presence of bacterial inflammation outside the central nervous system.

Cerebrospinal fluid procalcitonin and severe traumatic brain injury in children

OBJECTIVE

To determine the relationship between cerebrospinal fluid procalcitonin concentration and severe traumatic brain injury in children.

DESIGN

Prospective, observational clinical study.

SETTING

A multidisciplinary, tertiary-care pediatric intensive care unit.

PATIENTS

Twenty-eight patients who required external ventricular drainage for management of severe traumatic brain injury (Glasgow Coma Scale score of <8) and 22 control patients for whom lumbar cerebrospinal fluid evaluation excluded possible meningitis.

INTERVENTIONS

Standard intracranial pressure-directed neurointensive care, including intraventricular catheter placement and continuous cerebrospinal fluid drainage, was used to manage patients with severe traumatic brain injury.

MEASUREMENTS AND MAIN RESULTS

Demographic data including age, mechanism of injury, time of injury, initial Glasgow Coma Scale score, and outcome were collected. Cerebrospinal fluid procalcitonin concentration was determined by immunoluminometric assay. Initial cerebrospinal fluid procalcitonin concentration (median [range]) in patients with severe traumatic brain injury was increased greater than three-fold vs. controls (0.41 ng/mL [0.15-2.14] vs. 0.12 ng/mL [0.00-0.24], p <.001). Initial cerebrospinal fluid procalcitonin concentration among patients with abusive head trauma (0.31 ng/mL [0.29-0.50]) also was increased vs. controls (p <.05), although this increase was less robust than patients with accidental trauma (0.41 ng/mL [0.15-2.14], p <.001 vs. controls). Additional examination of key demographic and outcome variables with a generalized linear regression model was performed for patients with severe traumatic brain injury. Univariate analysis revealed that both time after injury (p <.01) and abusive head trauma as a mechanism of injury (p <.001) were associated with attenuation of the increased cerebrospinal fluid procalcitonin response after traumatic brain injury.

CONCLUSION

Cerebrospinal fluid procalcitonin concentration is increased in children after traumatic brain injury. The attenuated increase in cerebrospinal fluid procalcitonin among victims of abusive head trauma warrants further study because it may reflect impairment of endogenous neuroprotective mechanisms or delay in seeking medical attention. The significance of these observations remains to be determined as future studies elucidate the physiologic and mechanistic properties of procalcitonin.

Humoral markers of severity and prognosis of critical illness

Despite the considerable advances made in understanding the pathophysiology of systemic inflammation during critical illness, clinical progress has been elusive as it remains a very deadly condition. Cortisol and thyroid hormone levels can be as predictive of outcome as the commonly used severity parameters (i.e. APACHE). Indeed, levels of endocrine humoral substances such as arachidonic acids, nitric oxide, endothelin, calcitonin precursors, leptin and adenosine correlate with the severity and outcome of critical illness. Furthermore, calcitonin precursors represent a potentially new hormokine paradigm, being transcriptionally activated in all cells in response to infection. The cytokines are immune markers that often correlate with severity and outcome, but their release is transient. In contrast, the so-called acute phase proteins, such as C-reactive protein and serum amyloid A, are highly sensitive to inflammatory activity and can be important markers of severity and outcome. Leukocyte esterase, adhesion molecules, platelet activating factor and activated protein C are additional humoral immune markers; the replacement of the latter has been shown to be a promising therapeutic option. Natriuretic peptides are neurocrine humoral markers that have important cardiovascular implications. The level of macrophage migrating inhibitory factor, released by the pituitary, is elevated in sepsis and counteracts glucocorticoid action. Cellular markers to severe stress include the enhanced expression of protective substances in the form of heat shock proteins. High mobility group-1 is a DNA-binding protein and a late mediator of the inflammatory response. Apoptotic markers such as the soluble fas ligand are also elevated in inflammation. In summary, during critical illness, the endocrine, immune and nervous systems elaborate a multitude of humoral markers, the roles of which merit further scrutiny in order to improve therapeutic outcome.

Isolation and characterization of serum procalcitonin from patients with sepsis

Procalcitonin (PCT) is one of the precursors in the synthesis of calcitonin in thyroidal C-cells and other neuroendocrine cells. PCT and other calcitonin precursors are elevated in the serum of many conditions leading to systemic inflammatory response syndrome. The measurement of PCT in patients suffering from severe bacterial infections is a useful tool for the diagnosis of sepsis. Furthermore, therapeutic decisions are often based on the increase or decline of serum PCT levels. PCT was reported to have 116 amino acids. The aim of our study was the determination of the primary structure of serum PCT from septic patients. Sera containing high PCT-concentrations (>100 ng/ml) were collected from 22 patients with severe sepsis and were pooled for further purification (12.7 microg total concentration of PCT). Pooled PCT was purified on a CT 21-immunoaffinity column, further purified by reversed phase HPLC, and the resulting pure PCT was digested with endoproteinase Asp-N. N-terminal Edman sequencing showed that the first two amino acids (Ala-Pro) of the proposed pro-peptide were missing. Further analyses by MALDI-TOF mass spectroscopy resulted in a distinct mass signal of 12640 Da +/- 0.1%, which is in concordance with the theoretical molecular weight of the N-terminal truncated form (12628 Da). As opposed to previous suggestions, we could not detect any chemical modifications of PCT. In summary, we could demonstrate that PCT in the serum of septic patients is a peptide of only 114 amino acids, instead of the predicted 116 amino acids, lacking the N-terminal dipeptide Ala-Pro. This information on the primary structure of PCT might help in further studies on the physiological role of PCT during sepsis.

Calcitonin gene-related peptide expression in sepsis: postulation of microbial infection-specific response elements within the calcitonin I gene promoter

BACKGROUND

Recently, we reported an unexpected ubiquitous expression of calcitonin (CT)-mRNA in a hamster peritonitis model of sepsis. Using this animal model,we undertook a study to further investigate the pattern of expression of the calcitonin I (CALC-I) gene and CT gene-related peptide (CGRP)-mRNA in sepsis.

METHODS

Live Escherichia coli impregnated in agar pellets were implanted in the peritoneal cavities of hamsters. Twelve hours after sepsis induction, the septic and healthy control animals were sacrificed and tissues and peritoneal macrophages were collected. CGRP-mRNA content was evaluated by reverse transcription polymerase chain reaction (RT-PCR), quantitated by the Taq-Man technique, and compared with the mRNA expression of CT, tumor necrosis factor alpha (TNF-alpha), and interleukin-6 (IL-6). The 5' untranslated regions of the mRNA and potential alternative splicing sites were identified by 5' rapid amplification of cDNA ends.

RESULTS

We found a tissue-wide, ubiquitous and uniform expression of CGRP-mRNA in all septic tissues examined. CGRP-mRNA was detectable by RT-PCR in various extraneuronal and extrathyroidal septic tissues, but not in healthy control tissues. As found for CT-mRNA in our earlier studies, CGRP-mRNA seemed to be more specifically up-regulated as compared with other classical cytokines (ie, II-6 and TNF-alpha). Importantly, the 5' untranslated sequence in control and septic thyroid was similar to the sequence obtained from septic spleen.

CONCLUSIONS

We postulate the presence of microbial infection-specific response elements in the CALC-I gene promotor, which, upon a specific stimulus, override the tissue-selective expression pattern. This new form of endocrine plasticity may be of importance in the response to systemic inflammation.

Postnatal increase of procalcitonin in premature newborns is enhanced by chorioamnionitis and neonatal sepsis

BACKGROUND

To determine the influence of chorioamnionitis and neonatal sepsis on procalcitonin (PCT) levels in very-low-birth-weight (VLBW) infants within the first week of life.

DESIGN

PCT serum levels were measured in cord blood 1 h after delivery and on day 3 and day 7 of life. Chorioamnionitis and neonatal sepsis within the first week were monitored.

RESULTS

Chorioamnionitis was present in eight of 37 patients (21.6%). PCT on day 3 was increased in both the "No chorioamnionitis" (2.54 ng mL(-1), SEM 0.51) and "Chorioamnionitis" (6.96 ng mL(-1), SEM 2.93) groups of VLBW infants compared with the 1st hour values (0.45 and 0.58 ng mL(-1) SEM 0.07 and 0.11, respectively, P < 0.001) of the same patients. The postnatal gain was higher in the "Chorioamnionitis" group (P < 0.01). Neonatal sepsis was diagnosed (after exclusion) in 12 of 32 patients (37.5%). Mean values of maximum PCT in patients with and without sepsis were 8.41 ng mL(-1) (SEM 1.87) and 3.02 ng mL(-1) (SEM 1.38), respectively (P < 0.05). Sensitivity to sepsis of PCT, ratio of immature to total neutrophils (I : T), and C-reactive protein (CRP) were 75%, 50% and 25%, respectively.

CONCLUSIONS

In the group of VLBW infants the PCT level within 72 h of delivery was markedly increased in patients with chorioamnionitis. Compared with I : T and CRP, PCT appears to be a more sensitive marker of neonatal sepsis.

Procalcitonin following elective partial liver resection--origin from the liver?

BACKGROUND

The origin of the inflammatory peptide procalcitonin (PCT) is still unknown. In the present study PCT concentrations in arterial and hepatic-venous blood were examined in patients undergoing elective partial liver resection (LR) using a fiberoptic pulmonary arterial catheter placed in a liver vein to obtain further information on the origin of PCT.

METHODS

In 28 patients (21 male/7 female; average age of 58.8+/-8.8 years) undergoing LR, arterial and hepatic venous PCT concentrations were measured during 24 h perioperatively. The parallel blood withdrawals occurred immediately before the Pringle maneuver (Hx), 2 min, 1, 2, 6, 12, and 24 h after Hx. Over the whole period, the oxygen saturation in hepatic venous blood (ShvO2) was monitored. PCT concentrations were assayed by immunoluminometry.

RESULTS

We observed a significant increase in PCT concentration already 6 h after Hx compared to the values before Hx. Twenty-four hours after Hx we found the highest plasma concentrations. It was conspicuous that hepatic venous PCT concentrations were always higher than the arterial ones (significantly from the 6th hour after Hx). There was no correlation between the courses of ShvO2 and PCT rise. A significant correlation was verified between Hx duration and PCT concentration measured 24 h after Hx both in the hepatic venous and arterial blood.

CONCLUSIONS

The results of our investigation can be interpreted as evidence that liver (or the hepatosplanchnicus?) is a source of PCT. The mechanism of PCT induction cannot be clarified by our study: whether the induction of PCT was caused by an endotoxin translocation during the impeded splanchnic outflow or by the direct surgery-induced lesion (hypoxia) of the liver remains unclear. However, the latter appears more probable because of the observed correlation between Hx duration and PCT concentration rise.

Clinical evaluation of a new sensitive calcitonin assay: study of specificity

BACKGROUND

Calcitonin (CT) is the most sensitive marker available for medullary thyroid carcinoma, but it lacks specificity. Procalcitonin is the precursor protein of calcitonin. Infections are known to be associated with elevations of procalcitonin. The aim of this study was to evaluate a new sensitive calcitonin assay in a large population and to study the assay specificity in two particular populations: patients with renal failure and patients hospitalized in intensive care units with a high procalcitonin level.

METHODS

Using two immunometric assays (A and B) to detect only mature calcitonin, we evaluated the calcitonin level in 488 sera (46 stimulation tests) from 340 subjects.

RESULTS

The clinical evaluation showed that the calcitonin concentrations obtained with the two assays were similar for all patients except those with high procalcitonin levels. Among the patients, 12% (n=13) had basal calcitonin concentrations greater than 10 pg/ml with method A and 25.7% (n=25) with kit B. No correlation was found between calcitonin and procalcitonin concentrations.

CONCLUSION

The new sensitive calcitonin assay tested is very efficient especially for the low concentrations. The cross-reaction for high procalcitonin levels exists and is variable according to the kits used. The procalcitonin evaluation can help the interpretation of ambiguous calcitonin levels.

Procalcitonin as an acute phase marker

Procalcitonin is a 14-kDa protein encoded by the Calc-1 gene along with calcitonin and katacalcin. The function and regulation of this protein are quite different from those of the other gene products. Blood concentrations of procalcitonin are increased in systemic inflammation, especially when this is caused by bacterial infection. Studies of its behaviour in patients with bacterial sepsis have led to the proposal that it may be a useful marker of systemic bacterial infection, with greater specificity and sensitivity than acute phase proteins such as C-reactive protein.

Prognostic factors in intensive care

Predicting the outcome of critical illness remains an evolving art despite many recent advances. This review article describes the tools currently employed, appraising each in turn. The subject is viewed from the perspective that physiological reserve and inflammatory response are the essential elements in assessing prognosis in patients with multi-organ dysfunction/failure, the most commonly encountered syndrome in intensive care practice.

Procalcitonin for accurate detection of infection in haemodialysis

BACKGROUND

Infection results in considerable morbidity and mortality in haemodialysis patients. Diagnosis of infection can be difficult because currently applied laboratory parameters may be non-specifically altered due to uraemia or haemodialysis (HD). This study investigated the diagnostic value and kinetics of serum procalcitonin (PCT), a low-molecular-weight protein, in patients receiving intermittent HD.

METHODS

Sixty-eight patients receiving intermittent HD for end-stage renal disease (n=48) or acute renal failure (n=20) were prospectively studied, 47 treated with high-flux and 21 with low-flux membranes. Of 36 patients with severe infections or sepsis, 27 were treated with high-flux and nine with low-flux membranes. WBC, serum PCT and C-reactive protein (CRP) concentrations were measured immediately before HD, and PCT repeatedly during the following 48 h.

RESULTS

When determined immediately before HD, PCT demonstrated a sensitivity of 89%, a specificity of 81%, and positive and negative predictive values of 84 and 87%, indicating severe infection or sepsis. These levels were higher than the respective values for CRP (89, 48, 68 and 78%) and WBC (58, 75, 71 and 59%). After 4 h of HD with high-flux membranes, PCT decreased significantly to 83+/-25% and did not return to predialysis concentrations before 48 h. This decrease in serum PCT resulted in markedly reduced sensitivity (65%) and negative predictive value (54%). In contrast, no marked change in PCT concentration occurred during or after HD with low-flux membranes.

CONCLUSION

Serum PCT is an accurate indicator of severe infection and sepsis in patients receiving intermittent HD. High-flux membranes substantially decrease PCT. When utilizing high flux membranes, serum PCT concentrations should be determined prior to the start of HD.

In vitro modulation of inducible nitric oxide synthase gene expression and nitric oxide synthesis by procalcitonin

OBJECTIVE

Serum procalcitonin (PCT) concentration was recently introduced as valuable diagnostic marker for systemic bacterial infection and sepsis. At present, the cellular sources and biological properties of PCT are unclear. During sepsis and septic shock, inducible nitric oxide synthase (iNOS) gene expression is stimulated followed by the release of large amounts of nitric oxide (NO). We investigated the possible association between PCT and iNOS gene expression in an in vitro cell culture model.

DESIGN

Prospective, controlled in vitro cell culture study.

SETTING

University research laboratories.

INTERVENTIONS

Confluent rat vascular smooth muscle cells (VSMC) were incubated for 24 hrs and 48 hrs with PCT (1 ng/mL, 10 ng/mL, 100 ng/mL, 1,000 ng/mL, 5,000 ng/mL) alone or with the combination of tumor necrosis factor-alpha (TNF-alpha, 500 U/mL) plus interferon-gamma (IFN-gamma, 100 U/mL). iNOS gene expression was measured by qualitative as well as quantitative polymerase chain reaction analysis, NO release was estimated by the modified Griess method.

MEASUREMENTS AND MAIN RESULTS

PCT in increasing concentrations had no effect on iNOS gene expression and nitrite/nitrate release for 24 hrs and 48 hrs, respectively. However, PCT ameliorated TNF-alpha/IFN-gamma-induced iNOS gene expression in a dose-dependent manner (maximal inhibition at PCT 100 ng/mL by -66% for 24 hrs and -80% for 48 hrs). This was accompanied by a significantly reduced release of nitrite/nitrate into the cell culture supernatant (maximal reduction at PCT 100 ng/mL by -56% and -45% for 24 hrs and 48 hrs, respectively).

CONCLUSIONS

We conclude that recombinant PCT inhibits the iNOS-inducing effects of the proinflammatory cytokines TNF-alpha/ IFN-gamma in a dose-dependent manner. This might be a counter-regulatory mechanism directed against the large production of NO and the concomitant systemic hypotension in severe sepsis and septic shock.

Procalcitonin release patterns in a baboon model of trauma and sepsis: relationship to cytokines and neopterin

OBJECTIVES

Procalcitonin (PCT) has been described as an early, discriminating marker of bacteria-associated sepsis in patients. However, little is known of its source and actions, in part because no appropriate animal models have been available. We tested the hypothesis that plasma PCT increases during various pathophysiological conditions, such as hemorrhagic shock and sepsis, which differ with regard to the degree of associated endotoxemia. We further hypothesized that in sepsis, PCT would be significantly different in survivors vs. nonsurvivors.

DESIGN

Prospective, blinded analysis of previously collected plasma of experimental animals.

SETTING

Independent nonprofit research laboratory in a trauma hospital and a contract research institute.

SUBJECTS

A total of 22 male baboons (17.5-31 kg).

INTERVENTIONS

Hemorrhagic-traumatic shock was induced by hemorrhage for up to 3 hrs, reperfusion with shed blood and infusion of cobra venom factor (n = 7). By using a similar experimental setup, severe hyperdynamic sepsis was induced (n = 15) by intravenous infusion of live Escherichia coli (2 x 10(9) colony-forming units/kg) over 2 hrs, followed by antibiotic therapy (gentamicin 4 mg/kg twice a day).

MEASUREMENTS AND MAIN RESULTS

Plasma PCT at baseline was barely detectable, but levels increased significantly (p < .05) to 2+/-1.8 pg/mL 2 hrs after the start of reperfusion in the shock group, and to 987+/-230 pg/mL at 4 hrs after E. coli in the sepsis group. Levels were maximal between 6 and 32 hrs and had returned nearly to baseline levels at 72 hrs. Interleukin-6 levels paralleled the course of PCT measurements, whereas a significant increase in neopterin was seen at 24 hrs. PCT levels were approximately three times higher in the sepsis group than in the shock group, corresponding to endotoxin levels (at the end of hemorrhage, 286+/-144 pg/mL vs. 3576+/-979 pg/mL at the end of E. coli infusion; p = .003). PCT levels were significantly different at 24 hrs between survivors (2360+/-620 pg/mL) and nonsurvivors (4776+/-563 pg/mL) in the sepsis group (p = .032), as were interleukin-6 (1562+/-267 vs. 4903+/-608 pg/mL; p = .01) and neopterin/creatinine ratio (0.400+/-0.038 vs. 0.508+/-0.037; p = .032).

CONCLUSIONS

PCT is detectable in the baboon as in humans, both in hemorrhagic shock and sepsis. PCT levels are significantly higher in sepsis than in hemorrhage, a finding that is probably related to the differences in endotoxin. The baboon can be used for the study of PCT kinetics in both models; PCT kinetics are clearly different from other markers of sepsis, either IL-6 or neopterin, in both models. There are significant differences between survivors and nonsurvivors in the sepsis model.

Differentiated therapy with prostaglandin E1 (alprostadil) after orthotopic liver transplantation: the usefulness of procalcitonin (PCT) and hepatic artery resistive index (RI) for the evaluation of early graft function and clinical course

Increasing demand for donor organs has led to new pharmacological concepts for reducing ischemia-reperfusion injury (I/R) of the graft after liver transplantation to prevent primary non-functioning of the organ. Prostaglandins have proved to be cytoprotective in several experimental models of ischemia and transplantation. The prophylactic administration after orthotopic liver transplantation is still a subject of controversial discussion. The aim of our study was the evaluation of the post-transplant hepatic artery resistive index (RI) measured by color Doppler imaging, in combination with postoperative elevation of transaminases, as parameters indicating the need for a differentiated systemic therapy with prostaglandin E1 (PGE1) (alprostadil). In addition, the value of serum procalcitonin (PCT) as a postoperative parameter for the extent of I/R is investigated. In the case of post-transplant elevated hepatic artery RI (RI > 0.75), the administration of PGE1 led to a significant reduction of transaminases (p < 0.05) and a decline of the RI. In addition, postoperative PCT levels could be reduced significantly by PGE1 application. These results suggest that determination of RI is feasible for indicating a need for therapy with PGE1. Its targeted application reduces hepatocellular damage due to I/R after liver transplantation.

Usefulness of procalcitonin for diagnosis of infection in cardiac surgical patients

OBJECTIVE

To determine the value of procalcitonin (PCT) as a marker of postoperative infection after cardiac surgery.

DESIGN

A prospective single institution three phase study.

SETTING

University cardiac surgical intensive care unit (31 beds).

PATIENTS

Phase 1: To determine the normal perioperative kinetics of PCT, 20 consecutive patients undergoing elective cardiac surgery with cardiopulmonary bypass were included. Phase 2: To determine whether PCT may be useful for diagnosis of postoperative infection, 97 consecutive patients with suspected infection were included. Phase 3: To determine the ability of PCT to differentiate patients with septic shock from those with cardiogenic shock, 26 patients with postoperative circulatory failure were compared.

MEASUREMENTS AND MAIN RESULTS

Phase 1: Serum samples were drawn for PCT determination after induction of anesthesia (baseline), at the end of surgery, and daily until postoperative day (POD) 8. Baseline serum PCT concentration was 0.17 +/- 0.08 ng/mL (mean +/- SD). Serum PCT increased after cardiac surgery with a peak on POD 1 (1.08 +/- 1.36). Serum PCT returned to normal range on POD 3 and remained stable thereafter. Phase 2: In patients with suspected infection, serum PCT was measured at the same time of C-reactive protein (CRP) and bacteriologic samples. Among the 97 included patients, 54 were infected with pneumonia (n = 17), bacteremia (n = 16), mediastinitis (n = 9), or septic shock (n = 12). In the 43 remaining patients, infection was excluded by microbiological examinations. In noninfected patients, serum PCT concentration was 0.41 +/- 0.36 ng/mL (range, 0.08-1.67 ng/mL). Serum PCT concentration was markedly higher in patients with septic shock (96.98 +/- 119.61 ng/mL). Moderate increase in serum PCT concentration occurred during pneumonia (4.85 +/-3.31 ng/mL) and bacteremia (3.57 +/- 2.98 ng/mL). Serum PCT concentration remained low during mediastinitis (0.80 +/- 0.58 ng/mL). Five patients with mediastinitis, two patients with bacteremia, and one patient with pneumonia had serum PCT concentrations of <1 ng/mL. These eight patients were administered antibiotics previously and serum PCT was measured during a therapeutic antibiotic window. For prediction of infection by PCT, the best cutoff value was 1 ng/mL, with sensitivity 85%, specificity 95%, positive predictive value 96%, and negative predictive value 84%. Serum CRP was high in all patients without intergroup difference. For prediction of infection by CRP, a value of 50 mg/L was sensitive (84%) but poorly specific (40%). Comparing the area under the receiver operating characteristic curves, PCT was better than CRP for diagnosis of postoperative sepsis (0.82 for PCT vs. 0.68 for CRP). Phase 3: Serum PCT concentration was significantly higher in patients with septic shock than in those with cardiogenic shock (96.98 +/- 119.61 ng/mL vs. 11.30 +/- 12.3 ng/mL). For discrimination between septic and cardiogenic shock, the best cutoff value was 10 ng/mL, with sensitivity of 100% and specificity of 62%.

CONCLUSION

Cardiac surgery with cardiopulmonary bypass influences serum PCT concentration with a peak on POD 1. In the presence of fever, PCT is a reliable marker for diagnosis of infection after cardiac surgery, except in patients who previously received antibiotics. PCT was more relevant than CRP for diagnosis of postoperative infection. During a postoperative circulatory failure, a serum PCT concentration >10 ng/mL is highly indicative of a septic shock.

Disordered calcium homeostasis of sepsis: association with calcitonin precursors

BACKGROUND

Hypocalcemia and increased serum levels of calcitonin precursors are common in critically ill patients, especially in those with sepsis. We investigated calcium homeostasis in such patients.

PATIENTS AND METHODS

Serum concentrations of total and ionized calcium and known factors influencing or reflecting calcium homeostasis were measured in 101 consecutive patients of a medical intensive care unit. Calcitonin precursor levels were determined using a highly sensitive radioimmunoassay.

RESULTS

Critical illness per se was associated with decreased serum total and ionized calcium levels, which correlated with the severity of the underlying disease as measured by the APACHE II score. In addition, total and ionized hypocalcemia was more pronounced with increasing severity of infection (P < 0.02), and occurred in parallel with a marked increase of calcitonin precursors (P < 0.001). Mature calcitonin levels, however, remained normal. Changes of serum ionized calcium concentrations from admission to discharge correlated significantly with changes in the serum calcitonin precursor concentration (r2 = - 0.14, P < 0.001). Circulating vitamin D levels, parathyroid hormone levels and other markers reflecting calcium homeostasis did not correlate with the severity of infection.

CONCLUSIONS

In critically ill patients with sepsis, markedly elevated circulating calcitonin precursors might play a role in the development of the pronounced hypocalcemia. The specific calcitonin precursor(s) responsible for this effect and the pathophysiological mechanism remain to be elucidated.

Discrimination of sepsis and systemic inflammatory response syndrome by determination of circulating plasma concentrations of procalcitonin, protein complement 3a, and interleukin-6

OBJECTIVE

To evaluate whether plasma concentrations of procalcitonin (PCT), interleukin-6 (IL-6), protein complement 3a (C3a), leukocyte elastase (elastase), and the C-reactive protein (CRP) determined directly after the clinical onset of sepsis or systemic inflammatory response syndrome (SIRS) discriminate between patients suffering from sepsis or SIRS and predict the outcome of these patients.

DESIGN

Prospective study.

SETTING

Medical intensive care unit at a university hospital.

PATIENTS

Twenty-two patients with sepsis and 11 patients with SIRS.

MEASUREMENTS AND MAIN RESULTS

The plasma concentrations of PCT, C3a, and IL-6 obtained < or =8 hrs after clinical onset of sepsis or SIRS but not those of elastase or CRP were significantly higher in septic patients (PCT: median, 16.8 ng/mL, range, 0.9-351.2 ng/mL, p = .003; C3a: median, 807 ng/mL, range, 422-4788 ng/mL, p < .001; IL-6: median, 382 pg/mL, range, 5-1004 pg/mL, p = .009, all Mann-Whitney rank sum test) compared with patients suffering from SIRS (PCT: median, 3.0 ng/mL, range, 0.7-29.5 ng/mL; C3a: median, 409 ng/mL, range, 279566 ng/mL; IL-6: median, 98 pg/mL, range, 23-586 pg/mL). The power of PCT, C3a, and IL-6 to discriminate between septic and SIRS patients was determined in a receiver operating characteristic analysis. C3a was the best variable to differentiate between both populations with a maximal sensitivity of 86% and a specificity of 80%. An even better discrimination (i.e., a maximal sensitivity of 91% and a specificity of 80%) was achieved when PCT and C3a were combined in a "sepsis score." C3a concentrations also helped to predict the outcome of patients. Based on the sepsis score, a logistic regression model was developed that allows a convenient and reliable determination of the probability of an individual patient to suffer from sepsis or SIRS.

CONCLUSIONS

Our data show that the determination of PCT, IL-6, and C3a is more reliable to differentiate between septic and SIRS patients than the variables CRP and elastase, routinely used at the intensive care unit. The determination of PCT and C3a plasma concentrations appears to be helpful for an early assessment of septic and SIRS patients in intensive care.

Procalcitonin and cytokine levels: relationship to organ failure and mortality in pediatric septic shock

BACKGROUND

Procalcitonin (PCT), a marker of bacterial sepsis, may also act as a mediator of the inflammatory response to infection, and thus influence outcome.

OBJECTIVE

To investigate the relationship between PCT, interleukin (IL)-10, tumor necrosis factor (TNF), organ failure, and mortality in pediatric septic shock.

DESIGN

Prospective observational study.

SETTING

A 16-bed pediatric intensive care unit of a university hospital.

PATIENTS

A total of 75 children with septic shock having a median age of 43.1 months (range, 0.1-192 months). Children who had received antibiotics for >24 hrs were excluded. A total of 37 patients (49%) had meningococcal disease, and 72 patients (96%) required mechanical ventilation.

INTERVENTIONS

The pediatric risk of mortality (PRISM) score, multiple organ system failure (MOSF) score, duration of ventilation, length of ICU stay, and outcome were recorded. PCT, IL-10, and TNF were measured at admission to the intensive care unit. Sequential PCT levels were available at 0 hrs and 24 hrs in 39 patients (52%).

RESULTS

Observed mortality was 21/75 (28%). Data are median (range). The admission PCT (p = .0002) and TNF levels (p = .0001) were higher in children with higher MOSF scores. In survivors and nonsurvivors, the admission PCT was 82 ng/mL vs. 273 ng/mL (p = .03), IL-10 was 62 pg/mL vs. 534 pg/mL (p = .03), and TNF was 76 pg/mL vs. 480 pg/mL (p = .001), respectively. Area under the mortality receiver operating characteristic curve was 0.73 for PCT, 0.67 for IL-10, and 0.76 for TNF, compared with 0.83 for the PRISM score. Of 39 children, 16 (41%) with sequential PCT measurements showed no fall in PCT after 24 hrs treatment. These children had higher admission levels of IL-10 (p = .03), and TNF (p = .03) compared with children who demonstrated a subsequent fall in PCT. Although the former did not have a higher median PRISM (p = .28) or MOSF score (p = .19), observed mortality was 44% (7 of 16) compared with 9% (2 of 23) (p = .02).

CONCLUSION

The admission PCT, like TNF and IL-10, is related to the severity of organ failure and mortality in children with septic shock. A fall in PCT after 24 hrs of treatment may have favorable prognostic significance.

Serum procalcitonin levels in bacterial and abacterial meningitis

OBJECTIVES

To test the hypothesis that serum procalcitonin (PCT) levels are elevated in patients with bacterial meningitis and remain within normal limits in patients with abacterial meningitis.

DESIGN

Prospective case series.

SETTING

Tertiary care center.

PATIENTS

A total of 30 patients (13 men and 17 women) with a mean age of 52 yrs, having acute bacterial (n = 16) or abacterial (n = 14) meningitis.

INTERVENTIONS

Blood and cerebrospinal fluid samples.

MEASUREMENTS AND MAIN RESULTS

Patients with abacterial meningitis were younger and had a shorter hospital stay. Of 16 patients with bacterial meningitis, 14 were in a septic condition at admission, but only 5 of 14 patients with abacterial meningitis were in a septic condition at admission. At discharge, 12 patients were without symptoms, 9 patients were moderately disabled, and 9 were severely disabled. No patient died. At admission, PCT, C-reactive protein, white blood cell and cerebrospinal fluid leukocyte counts, and cerebrospinal fluid protein and lactate levels were higher and the serum/cerebrospinal fluid glucose quotient was lower in patients with bacterial meningitis as compared with those with abacterial meningitis (p < .001). PCT was the variable with the highest specificity for bacterial infections (100%), but there were false-negative findings in five patients with bacterial meningitis (a sensitivity of 69%). Persistently elevated or increasing PCT levels after 2 days were associated with an unfavorable clinical course.

CONCLUSIONS

Our results indicate that PCT is a useful additional variable for distinguishing bacterial from abacterial meningitis. In patients with abacterial meningitis, PCT levels do not increase even in cases of viral sepsis. Elevated PCT levels indicate a bacterial origin with high specificity, but false-negative results can occur.

Relationship between procalcitonin plasma levels and severity of injury, sepsis, organ failure, and mortality in injured patients

OBJECTIVE

To compare procalcitonin (PCT) plasma levels of injured patients with the incidence and severity of systemic inflammatory response syndrome (SIRS), infection, and multiple organ dysfunction syndrome (MODS) and to assess the predictive value of PCT for these posttraumatic complications.

DESIGN

Retrospective study comparing patients with mechanical trauma in terms of severity of injury, development of infectious complications, and organ dysfunctions.

SETTING

Level I trauma center with emergency room, intensive care unit, and research laboratory.

PATIENTS

Four hundred five injured patients with an Injury Severity Score of > or =9 points were enrolled in this study from January 1994 to February 1996.

INTERVENTIONS

Blood samples were collected on the day of admission and on days 1, 3, 5, 7, 10, 14, and 21 thereafter.

MEASUREMENTS AND MAIN RESULTS

We determined PCT serum levels using a specific immunoluminometric assay. We retrospectively evaluated the occurrence of SIRS, sepsis, and MODS using patients' charts. Mechanical trauma led to increased PCT plasma levels dependent on the severity of injury, with peak values on days 1 and 3 (p < .05) and a continuous decrease within 21 days after trauma. Patients who developed SIRS demonstrated a significant (p < .05) increase of peak PCT plasma levels compared with patients without SIRS. The highest PCT plasma concentrations early after injury were observed in patients with sepsis (6.9+/-2.5 ng/mL; day 1) or severe MODS (5.7+/-2.2 ng/mL; day 1) with a sustained increase (p < .05) for 14 days compared with patients with an uneventful posttraumatic course (1.1+/-0.2 ng/mL). Moreover, these increased PCT plasma levels during the first 3 days after trauma predicted (p < .0001; logistic regression analysis) severe SIRS, sepsis, and MODS.

CONCLUSIONS

These data indicate that PCT represents a sensitive and predictive indicator of sepsis and severe MODS in injured patients. Routine analysis of PCT levels seems to aid early recognition of these posttraumatic complications. Thus, PCT may represent a useful marker to monitor the inflammatory status of injured patients at risk.

Calcitonin precursors are reliable markers of sepsis in a medical intensive care unit

OBJECTIVE

The diagnosis of infection in critically ill patients is challenging because traditional markers of infection are often misleading. For example, serum concentrations of calcitonin precursors are increased in patients with infections. However, their predictive accuracy for the diagnosis of sepsis in unselected patients in a medical intensive care unit (ICU) is unknown. Therefore, we compared the usefulness of serum concentrations of calcitonin precursors, C-reactive protein, interleukin-6, and lactate for the diagnosis of sepsis in consecutive patients suffering from a broad range of diseases with an anticipated stay of > or =24 hrs in a medical ICU.

DESIGN

Prospective cohort study.

SETTING

Medical intensive care unit in a university medical center.

PATIENTS

101 consecutive critically ill patients.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected at various time points during the course of the disease. Systemic inflammatory response syndrome, sepsis, severe sepsis, and septic shock were diagnosed according to standardized criteria, and patients were reclassified daily without prior knowledge of the serum concentrations of calcitonin precursors or interleukin-6. At admission, 99% of the patients had systemic inflammatory response syndrome, 53% had sepsis, and 5% developed sepsis during their stay in the ICU. Calcitonin precursors, C-reactive protein, interleukin-6, and lactate levels increased with the severity of infection (p < .01, one-way analysis of variance). In a receiver operating characteristic curve analysis, calcitonin precursors were found to be the most reliable laboratory variable for the diagnosis of sepsis as compared with C-reactive protein, interleukin-6, and lactate (p < .01, for each comparison). Calcitonin precursor concentrations of >1 ng/mL had sensitivity of 89% and specificity of 94% for the diagnosis of sepsis. High serum concentrations of calcitonin precursors were associated with poor prognosis (p = .01).

CONCLUSIONS

In a medical ICU, serum calcitonin precursor concentrations are more sensitive and are specific markers of sepsis as compared with serum C-reactive protein, interleukin-6, and lactate levels.

Procalcitonin behaves as a fast responding acute phase protein in vivo and in vitro

OBJECTIVES

Procalcitonin (PCT) is a 13 kD protein of which plasma concentrations are strongly increased in inflammatory states. PCT concentrations are claimed to have a more powerful discriminatory value for bacterial infection than the acute phase proteins serum amyloid A (SAA) or C-reactive protein (CRP). The source of production and its mechanism of induction are unknown. We investigated the inducibility of PCT both in vivo and in vitro and compared the behavior of PCT with those of SAA and CRP.

DESIGN

A prospective descriptive patient sample study and a controlled liver tissue culture study.

SETTING

A university hospital.

PATIENTS

Cancer patients who were treated with human tumor necrosis factor-alpha (rhTNF-alpha; 5 patients) or interleukin-6 (rhIL-6; 7 patients).

MEASUREMENTS AND MAIN RESULTS

Serial serum samples were collected for analysis of concentrations of PCT, SAA, and CRP. In the TNF-alpha group, frequent sampling was performed on the first day to allow analysis of initial responses. In a human liver slice model, the release of PCT, SAA, and CRP was measured on induction with rhTNF-alpha and rhIL-6 for 24 hrs. We found that PCT displayed acute phase reactant behavior in vivo after administration of both rhTNF-alpha and rhIL-6. After rhTNF-alpha-administration, PCT reached half-maximal concentrations within 8 hrs, 12 hrs earlier than either SAA or CRP did. PCT, SAA, and CRP were produced in detectable quantities by liver tissue in vitro. PCT production by liver slices was enhanced after stimulation with rhTNF-alpha or rhIL-6; SAA and CRP concentrations were elevated after stimulation with rhTNF-alpha.

CONCLUSIONS

We found that PCT and acute phase proteins such as CRP are induced by similar pathways. The liver appears to be a major source of PCT production. Thus, PCT may be considered an acute phase protein. The different kinetics of PCT, rather than a fundamentally different afferent pathway, may explain its putative diagnostic potential to discriminate bacterial infection from other causes of inflammation.

Molecular aspects and natural source of procalcitonin

The search for sensitive and specific markers of systemic infection has shown that procalcitonin levels are increased in sepsis, and, consequently, this plasma protein has come into the focus of clinical research. Human procalcitonin is encoded by the Calc-l gene, which gives rise to two alternatively spliced transcripts. Despite systemic investigation of the Calc-l gene and mechanisms of the tissue-specific regulation and alternative splicing, little is known about the biology of procalcitonin and the cells which express this protein during inflammation. Here we focus on the molecular and biochemical properties of the molecule and summarize the known biological functions of procalcitonin. We report on the structure of the Calc-l gene, the amino acid conservation of procalcitonin in different species, and the consensus sequences of the protein with regard to sites relevant for posttranslational modification, spatial distribution, and homologies to other cytokines. We discuss aspects of intracellular location of procalcitonin and demonstrate that it has the characteristics of a secreted protein.