Clinical application of C-reactive protein in infective endocarditis

Background The prognostic value of serum C-reactive protein(CRP) in patients with infective endocarditis(IE) is not well elucidated. This study aimed to evaluate the usefulness of CRP in predicting the outcome of IE.Methods Two hundred ninty-six patients from 2009 to 2012 in the Department of Cardiology at Guangdong General Hospital were screened and divided into surgical and conventional treatment groups. CRP, white blood cell(WBC), erythrocyte sedimentation rate(ESR) and other clinical data were obtained with follow-up for 12 months. Results Two hundred thirty-six patients were assigned to receive surgery treatment while 60 patients received conventional treatment. In the surgery group, the level of CRP in the death patients was significantly higher than that in the survival patients(P0.001). The area under the curve of ROC was about 0.749(SE0.064,P=0.005, 95%CI, 0.624-0.874) and the cut-off point of CRP was 23.8 mg/L. In conventional group, there was significant difference between death and survival(P 0.001). The area under the curve of ROC was about 0.701(SE0.095, P =0.032, 95%CI, 0.515-0.888) and the cut-off points of CRP was 65.6 mg/L. There were no significant differences in WBC and ESR between surgery and conventional groups. Conclusion A more aggressive surgical intervention results in a better outcome over conventional treatment and CRP could be served as a predictive marker for adverse outcome in IE patients.     

Comparison of interleukin-6 and C-reactive protein serum concentrations assessment in diagnosis of infective endocarditis

Serum interleukin-6 (IL-6) level might be used to aid in diagnosis of infective endocarditis (IE), especially when blood cultures are negative. One of typical acute phase proteins is C-reactive protein (CRP), often served as an additional inflammation maker. The aim of the study was to compare serum IL-6 and CRP concentrations assessment in diagnosis and monitoring of IE. The study group consisted of 40 patients with ongoing IE and valvular heart diseases. Two control groups consisted of patients with valvular heart diseases: 15 without infection and another 15 with urinary tract infection. The diagnosis of IE was established according to the Duke University criteria; in 34 patients positive blood cultures were found. Serum IL-6 and CRP were measured on three occasions after diagnosis of IE was established and during antimicrobial treatment (mean period 14 +/- 7 days) by ELISA. Usefulness of both parameters for IE diagnosis were described. Reference values were defined as 0-12.5 pg/ml for IL-6, and 0-10 mg/l for CRP. Mean concentrations of IL-6 and CRP in patients with IE (37 +/- 44.3 pg/ml and 27.1 +/- 23.9 mg/l) were significantly higher than in controls: with urinary tract infection (9.1 +/- 4.42 pg/ml and 6.95 +/- 4.39 mg/l) and without infection (3.95 +/- 1.4 pg/ml and 2.21 +/- 0.96 mg/l). CRP concentration was not significantly correlated with IL-6 (r = 0.51, p = 0.07). The significant tendency of consecutive IL-6 concentrations to decrease (from 37 +/- 44.3 to 8.7 +/- 5.7 pg/ml), without decrease of CRP (from 27.1 +/- 23.9 mg/l to 22 +/- 18.3 mg/l) was found. CONCLUSIONS: 1. Elevated serum IL-6 and CRP levels may suggest ongoing IE. 2. Sensitivity, specificity, positive and negative predictive value are nonsignificantly higher for IL-6 than CRP. 3. Combined assessment of serum IL-6 and CRP concentration has no higher value in diagnosis of IE. 4, IL-6 level decrease is faster than CRP during antimicrobial treatment, and it helps better and faster monitoring of treatment.     

Correlation study of sleep efficiency with C-reactive protein and IL-6 in patients with infective endocarditis

Background Sleep disorders have been found in patients with infective endocarditis(IE)and are reported to have a strong correlation with inflammation. In this study,we measured the serum levels of inflammatory factors and evaluated the correlations of postoperative sleep efficiency with C-reactive protein and interleukin-6(IL-6)in IE patients. Methods A total of 117 post-operative patients with IE were enrolled in the study. All patients were tested using a wearable actigraphy device for their sleep efficiency. All patients were examined for C-reactive protein,and 72 patients were tested for IL-6. Results A correlation analysis was performed between C-reactive protein and IL-6. The average sleep efficiency of most of the IE patients was 80.81±8.52%,and the average result of the C-reactive protein test was 29.98±26.3 mg/L. The correlation coefficient between sleep efficiency and C-reactive protein was-0.3011. The average result of the IL-6 test was 24.52±23.85 pg/mL,and the correlation coefficient between sleep efficiency and IL-6 was-0.3543. Conclusions Postoperative sleep efficiency is negatively correlated with serum levels of C-reactiveprotein and IL-6 in patients with IE.[S Chin J Cardiol2019;20(2):103-107]     

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.     

Utility of serum C-reactive protein in assessing the outcome of infective endocarditis.

AIMS: To evaluate the diagnostic usefulness of serial serum C-reactive protein determinations in monitoring the outcome of infective endocarditis (IE). METHODS AND RESULTS: C-reactive protein, erythrocyte sedimentation rate (ESR), and white blood cell count (WBC) were measured from admission until week 10 in 129 patients with 134 episodes of IE. Need for cardiac surgery and final outcome were assessed until 3 months from admission. Data were evaluated using extensive statistical analyses. The fall in serum C-reactive protein or WBC was significantly faster when a patient had an uncomplicated recovery than when complications developed or death ensued, but no such behaviour was observed in ESR. None of the 80 patients who had normal C-reactive protein by week 10 died of IE. Moreover, none of the 22 patients who had normal C-reactive protein by week 4 needed cardiac surgery and only two of the 33 patients who had normal C-reactive protein by week 6 needed cardiac surgery, both after successful medical treatment of IE. Of the 87 patients whose WBC normalized within 4 weeks, six died and 15 needed valve surgery. CONCLUSION: The normalization of C-reactive protein proved to be a good predictor of a favourable late outcome (surgery, death) of IE. Also WBC count proved useful in the assessment of patients with IE, but the value of ESR was negligible.     

Pro-inflammatory cytokines and C-reactive protein are associated with undernutrition in the context of Schistosoma japonicum infection.

Schistosomiasis is associated with undernutrition, but the mechanisms involved remain unknown. We analyzed baseline and follow-up data from a longitudinal treatment-reinfection study in N = 477 Schistosoma japonicum-infected subjects 7-20 years of age from Leyte, the Philippines. After baseline treatment with praziquantel, follow-up visits were scheduled every 3 months for 18 months; stool, venous blood, and anthropometric measurements were collected at each visit. Cytokine production by peripheral blood mononuclear cells (PBMCs) stimulated with specific S. japonicum antigens was measured once 4 weeks after treatment. After adjustment for confounders, S. japonicum intensity was associated with decreased serum albumin and Z-scores (all P < 0.05) and with increased serum C-reactive protein (CRP) and interleukin (IL)-6. CRP was associated with decreased albumin and Z-scores (all P < 0.01). Production of IL-1b and tumor necrosis factor (TNF)-alpha in response to worm antigen was associated with decreased albumin (both P < 0.005) and height-for-age Z-score (TNF-alpha only, P = 0.05). S. japonicum-associated undernutrition may, in part, result directly from inflammation.     

血清IL-6、CRP、PCT水平对新生儿败血症的诊断价值

目的 探讨IL-6、C反应蛋白(CRP)、降钙素原(PCT)诊断新生儿败血症的价值.方法 选择临床诊断为败血症的患儿67例(观察组),另选同期无感染症状的30例新生儿作为对照组.采用ELISA双抗夹心法测定两组IL-6水平,固相免疫层析法半定量测定PCT水平,定量免疫速率比浊法测定CRP水平;以临床常用标准作为阳性诊断阈值,观察各指标诊断新生儿败血症敏感性、特异性、阳性预测值、阴性预测值及约登指数.以灵敏度为纵坐标,1-特异度为横坐标,分析ROC曲线,从而确定检测的最佳阈值.结果 IL-6的敏感性、特异性、阳性预测值、阴性预测值和约登指数及ROC曲线下的面积值均优于CRP和PCT.而三个指标联合诊断的敏感性优于各指标独立诊断.结论 IL-6对新生儿败血症有很好的临床诊断价值;疑诊新生儿败血症者应考虑多个指标联合应用,以提高诊断准确率.     

Evaluation of C-reactive protein, interleukin-6, and procalcitonin levels in allogeneic hematopoietic stem cell recipients

BACKGROUND: Prompt detection of transplant-related complications (TRC) as infections, acute graft-versus-host disease (aGVHD), microangiopathic hemolytic anemia, or veno-occlusive disease following allogeneic hematopoietic stem cell transplantation (HSCT) is essential. PATIENTS AND METHODS: We conducted a prospective trial on clinical significance of C-reactive protein (CRP), interleukin-6 (IL-6) and procalcitonin (PCT) serum levels in TRC. A total of 350 stem cell recipients were admitted. CRP, IL-6 and PCT were analyzed prior to conditioning and weekly until 8 wk after HSCT. TRC were recorded weekly throughout the study. RESULTS: CRP (4.4 mg/dL vs. 12.8 mg/dL; P < 0.001), IL-6 (93 ng/mL vs. 1.138 ng/mL; P < 0.001) and PCT (0.8 ng/dL vs. 5.7 ng/dL; P < 0.001) were increased in infectious complications. Only PCT differentiated between infection and other TRC. Exclusive aGVHD did not increase CRP (4.4 mg/dL vs. 5.7 mg/dL; n.s.), IL-6 (93 ng/mL vs. 153 ng/mL; n.s.) and PCT (0.8 ng/dL vs. 0.8 ng/dL; n.s.). CRP (6.1 mg/dL vs. 3.1 mg/dL; P < 0.001) and IL-6 (295 ng/mL vs. 122 ng/mL; P = 0.001) were decreased during steroid therapy, but not PCT (2.3 ng/dL vs. 2.0 ng/dL; n.s.). CONCLUSION: Our study confirmed CRP, IL-6 and PCT serum levels as helpful markers for TRC. PCT can differentiate infection from GVHD despite steroid therapy. Further trials are needed focusing on the identification of patients who benefit from early risk stratification.     

Interrelations between interleukin-6, interleukin-1 beta, plasma C-reactive protein values, and in vitro C-reactive protein generation in patients with inflammatory bowel disease.

Acute phase proteins are released from the liver in response to cytokines, and measurement of serum concentrations offers a valuable means of assessing inflammatory bowel disease. C-reactive protein (CRP) is a participating prominent component of the acute phase response in active Crohn's disease. This study aimed at determining the comparative role of the cytokines interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6), in driving CRP production in inflammatory bowel disease, and to test the hypothesis that there is a difference in the profile of cytokines generated in these two conditions. Serum CRP, the release of the cytokines IL-1 beta and IL-6 from monocytes, and the ability of monocyte conditioned medium to stimulate CRP synthesis by hepatocytes in an in vitro system was measured in patients with ulcerative colitis and Crohn's disease. Monocytes from patients with Crohn's disease produced more 1L beta-1 than monocytes from patients with ulcerative colitis or normal controls. There was no increased tendency for monocytes from Crohn's disease patients to produce more 1L-6, so the greater circulating values of IL-6 reported by a number of authors in Crohn's disease may reflect the participation of a larger number of cells of the monocyte-macrophage series, or production of IL-6 by other cell types. Correlation of cytokine production by monocytes with in vitro CRP release from cultured hepatocytes in response to monocyte conditioned medium showed that, in that system, IL-1 beta was the stronger stimulus to CRP production. Some of the differences in the inflammatory processes of ulcerative colitis and Crohn's disease may reflect differences in the amount of IL-1beta and IL-6 generated from macrophages and monocytes.     

Usefulness of cytokines interleukin-6 and interleukin-2R concentrations in diagnosing active infective endocarditis involving native valves

The most important diagnostic value in infective endocarditis (IE) is isolation of the causative microorganism. Because premature antibiotic treatment is commonly administered before the assessment of blood cultures, the percentages of isolated microorganisms has decreased significantly within the last decades. Therefore, additional criteria for the diagnosis of IE may be helpful. It was hypothesized that assessment of interleukin-6 (IL-6) and interleukin-2R (IL-2R) may provide new diagnostic criteria for inflammation in IE. IL-6 and IL-2R serum concentrations, white blood cell count (WBC), and C-reactive protein (CRP) were measured in the blood of 47 patients with IE at the time of diagnosis and during treatment. WBC and CRP were elevated in patients with IE at the time of diagnosis. Both parameters were higher (p <0.05) in patients with positive blood cultures when compared with negative cultures. The differences persisted during the first week of treatment (p <0.01). In contrast, IL-6 and IL-2R concentrations were elevated (p <0.001) independently of the status of blood cultures. Serum concentrations of IL-6 and IL-2R decreased continuously during antibiotic treatment. Assessment of IL-6 and IL-2R could thus provide new diagnostic criteria for inflammation in IE, and these interleukins could also be suitable for monitoring the course of inflammation during treatment.     

Independent association between inflammatory markers (C-reactive protein, interleukin-6, and TNF-alpha) and essential hypertension

High blood pressure (HBP) has been associated with elevated C-reactive protein (CRP), a marker of chronic mild inflammation. However, the association between HBP and other inflammatory markers, particularly interleukin 6 (IL-6) and tumour necrosis alpha (TNF-alpha), has not been evaluated in well-controlled studies. We examined the cross-sectional relationship between IL-6, TNF-alpha, and CRP and HBP in a random sample of 196 healthy subjects. All markers were measured in duplicate with high-sensitivity ELISA tests. Three blood pressure (BP) measurments were averaged for the analysis, and subjects with systolic BP >or=140 and/or diastolic BP >or=90 mmHg were considered hypertensive. Log binomial regression was used to estimate multivariate-adjusted prevalence ratios (PR) of HBP. Of the subjects, 40% (79) were hypertensive (mean age: 44 years; range 30-64). After adjustment for age, sex, body mass index, family history of HBP, and the level of the other inflammatory markers, subjects in the second (PR: 3.10, P=0.003), third (PR: 2.32; P=0.031), and fourth quartiles (PR: 2.30; P=0.036) of IL-6 were more than twice as likely to be hypertensive than those in the first quartile. Corresponding PR estimates for TNF-alpha levels were 1.41 (P=0.014) for the second; 1.59 (P=0.001) for the third; and 1.61 (P=0.025) for the fourth quartile. The CRP-HBP association was not statistically significant. Our results suggest that TNF-alpha and IL-6 could be independent risk factors for HBP in apparently healthy subjects. Nevertheless, the temporal relationship between elevated inflammation markers and HBP should be ascertained in prospective cohort studies.     

Simvastatin inhibits interleukin-6 release in human monocytes stimulated by C-reactive protein and lipopolysaccharide

BACKGROUND: The accumulating evidence suggests that C-reactive protein (CRP) may have direct inflammatory effects on the vascular wall and that statin therapy may have important non-lipid anti-inflammatory effects confirmed by decreasing serum inflammatory markers, such as CRP. However, the effect of simvastatin on interleukin-6 (IL-6) release in cultured human monocytes was not investigated.DESIGN A prospective, human monocyte culture, simvastatin intervention study. METHODS: Monocytes were isolated from blood of healthy volunteers by the Ficoll density gradient and stimulated by broad concentrations of CRP (1-20 microg/ml) and lipopolysaccharide (LPS, 1-10 ng/ml) at indicated time points (0, 2, 4, 8, 16 and 24 h). Also 10-8-10-6 mol/l simvastatin was coincubated with cells in the presence of CRP and LPS. Measurements of IL-6 were performed from supernatants of cultured medium in duplicate, using a commercial assay kit. RESULTS: CRP and LPS induced the rapid release of IL-6, with significantly elevated levels in cultured supernatants at 4 h in the CRP group and at 2 h in the LPS group. The effects of CRP and LPS on IL-6 release of monocytes were dose and time dependent. A greater than 11-fold increase of IL-6 in the CRP group (20 microg/ml) and a greater than 26-fold increase in the LPS group (10 ng/ml) were observed at 24 h compared with the control group (945.7+/-98.3 pg/ml compared with 94.3+/-12.4 pg/ml and 1720.4+/-690.1 pg/ml compared with 70.1+/-16.7 pg/ml, P<0.001, respectively). However, 10-8-10-6 mol/l simvastatin inhibited significantly the production of IL-6 in monocytes stimulated by CRP and LPS in a dose-dependent manner, with the maximal inhibiting effect at a concentration of 10-6 mol/l (945.7+/-98.3 pg/ml compared with 180.9+/-31.2 pg/ml and 1720.4+/-690.1 pg/ml compared with 824.0+/-206.2 pg/ml, P<0.001 respectively). CONCLUSIONS: CRP and LPS could induce IL-6 release in human monocytes and simvastatin could inhibit this response in a dose-dependent manner, which may provide an insight into the mechanisms of anti-inflammatory or anti-atherosclerotic actions of simvastatin.     

The role of preoperative C-reactive protein and procalcitonin as predictors of post-pancreaticoduodenectomy infective complications: A prospective observational study

Introduction

The common causes of morbidity after pancreaticoduodenectomy (PD) are infective complications. Till date, no specific preoperative markers have been identified to determine the probability of developing infective complications. We have studied the factors predicting the occurrence of the infective complication/s in the present study.

Methods

The present prospective observational study included 133 consecutive patients who underwent PD from January 2011 to June 2016 at a specialized hepatopancreaticobiliary surgical oncology unit. The surgeries were done using a standardized technique. Postoperative complications were segregated into two categories—(a) infective (e.g. cholangitis) and (b) non-infective (e.g. delayed gastric emptying). Increased age, preoperative serum albumin levels, preoperative biliary stenting, pre-stenting serum bilirubin levels, duration of common bile duct stenting, preoperative C-reactive protein [CRP], and procalcitonin [PCT] were evaluated.

Results

Overall morbidity rate was 48.8%. Morbidity associated with infective complications was 21.8%. Increased age, preoperative serum albumin levels, and pre-stenting serum bilirubin levels did not increase the rate of the infective complications. The association between preoperative PCT and preoperative CRP with the infective complications was significant with a p-value of <0.01 (6.75E-07) and <0.01 (4.80E-10), respectively. In the multivariate analysis, only the elevated preoperative procalcitonin was a statistically significant predictor of postoperative infective complications.

Conclusion

Preoperative PCT and CRP levels done 48 h before surgery are sensitive, specific, easily available, and cost-effective predictors of infective complications after PD.

     

降钙素原及白介素6,C-反应蛋白联合检测在社区获得性肺炎治疗中的临床意义

目的探究降钙素原及白介素6,C-反应蛋白联合检测在社区获得性肺炎治疗中的临床意义。方法选取我科2012年11月-2014年11月的56例社区获得性肺炎患者,作为观察组。另选取同期来我科就诊的47例上呼吸道感染患者作为对照组,分别于住院第1、4、7天对患者降钙素原、白介素6、C-反应蛋白水平进行检测,对结果进行分析。结果观察组三种指标水平均显著高于对照组,随着治疗的进行,指标水平有所下降,差异有统计学意义,P0.05;死亡组各指标水平均显著高于对照组,且随着住院时间的增加,好转组指标水平逐渐下降,死亡组逐渐攀升,差异有统计学意义,P0.05;三种指标第1天对社区获得性肺炎诊断的灵敏度分别为PCT 89.3%(50/56)、CRP 100%(56/56)、IL-6 87.5%(49/56),特异度分别为PCT 95.7%(45/47)、CRP 83.0%(39/47)、IL-6 78.7%(37/47)。结论降钙素原及白介素6,C-反应蛋白联合检测,对社区获得性肺炎的诊断有较高的临床价值,对患者的治疗,预后的评估有重要的指导意义。     

Cytokines IL-1beta, IL-6, and TNF-alpha enhance in vitro growth of bacteria.

We have previously reported that in acute respiratory distress syndrome (ARDS), nonsurvivors have persistent elevation in pulmonary and circulating proinflammatory cytokine levels over time and a high rate of nosocomial infections antemortem. In these patients, none of the proven or suspected nosocomial infections caused a transient or sustained increase in plasma proinflammatory cytokine levels above preinfection values. We hypothesized that cytokines secreted by the host during ARDS may favor the growth of bacteria. We conducted an in vitro study of the growth of three bacteria clinically relevant in nosocomial infections, evaluating their in vitro response to various concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6. We found that all three bacterial species showed concentration-dependent growth enhancement when incubated with one or more tested cytokines and that blockade by specific neutralizing cytokine MoAb significantly inhibited cytokine-induced growth. When compared with control, the 6-h growth response (cfu/ml) was maximal with IL-1beta at 1,000 pg for Staphylococcus aureus (36 +/- 16 versus 377 +/- 16; p = 0.0001) and Acinetobacter spp. (317 +/- 1,147 versus 1,124 +/- 147; p = 0.002) and with IL-6 at 1,000 pg for Pseudomonas aeruginosa (99 +/- 50 versus 509 +/- 50; p = 0.009). The effects of cytokines were seen only with fresh isolates and were lost with passage in vitro on bacteriologic medium without added cytokines. In this study we provide additional evidence for a newly described pathogenetic mechanism for bacterial proliferation in the presence of exaggerated and protracted inflammation.     

Copeptin, C-reactive protein, and procalcitonin as prognostic biomarkers in acute exacerbation of COPD

BACKGROUND: A novel approach to estimate the severity of COPD exacerbation and predict its outcome is the use of biomarkers. We assessed circulating levels of copeptin, the precursor of vasopressin, C-reactive protein (CRP), and procalcitonin as potential prognostic parameters for in-hospital and long-term outcomes in patients with acute exacerbation of COPD (AECOPD) requiring hospitalization. METHODS: Data of 167 patients (mean age, 70 years; mean FEV(1), 39.9 +/- 16.9 of predicted [+/- SD]) presenting to the emergency department due to AECOPD were analyzed. Patients were evaluated based on clinical, laboratory, and lung function parameters on hospital admission, at 14 days, and at 6 months. RESULTS: Plasma levels of all three biomarkers were elevated during the acute exacerbation (p < 0.001), but levels at 14 days and 6 months were similar (p = not significant). CRP was significantly higher in patients presenting with Anthonisen type I exacerbation (p = 0.003). In contrast to CRP and procalcitonin, copeptin on hospital admission was associated with a prolonged hospital stay (p = 0.002) and long-term clinical failure (p < 0.0001). Only copeptin was predictive for long-term clinical failure independent of age, comorbidity, hypoxemia, and lung functional impairment in multivariate analysis (p = 0.005). The combination of copeptin and previous hospitalization for COPD increased the risk of poor outcome (p < 0.0001). Long-term clinical failure was observed in 11% of cases with copeptin < 40 pmol/L and no history of hospitalization, as compared to 73% of patients with copeptin >/= 40 pmol/L and a history of hospitalization (p < 0.0001). CONCLUSIONS: We suggest copeptin as a prognostic marker for short-term and long-term prognoses in patients with AECOPD requiring hospitalization.     

血清降钙素原及C反应蛋白在感染性疾病中的应用前景

血清降钙素原（PCT）是降钙素前肽物质,正常情况下由甲状腺C细胞产生。C反应蛋白（CRP）是一种急性时相反应蛋白,在白细胞介素-6作用下由肝细胞分泌产生。有关资料表明,感染时血清PCT及CRP水平升高,并与感染严重程度呈正相关。在临床检测中发现两者在诊断感染性疾病灵敏度上差异不明显,但在特异性上PCT明显高于CRP。两者联合检测在鉴别诊断感染性疾病和非感染性疾病、监测危重症及感染、指导抗生素的合理应用、判断治疗效果及评估预后上有重要的临床应用价值与良好的应用前景。PCT产生机制及其在重症感染时的来源、作用机制尚不清楚,有待于进一步研究。