降钙素原在新生儿细菌感染中的诊断价值

目的探讨降钙素原(PCT)在新生儿重症感染时的诊断价值。方法将167例住院新生儿分严重感染组、一般感染组、非感染组、恢复期组4组,检测血清PCT、血清CRP、白细胞计数及分类,进行结果分析。结果以PCT≥0·5ng/ml为阳性,各组阳性:重感染组为88·00%,一般感染组为55·00%,非感染组为14·29%,恢复期组为9·52%,严感染组阳性率明显高于其他3组与3组间两两比较,差异有统计学意义(Hc=73·24,P<0·00)。结论PCT可作为新生儿感染的早期检测指标,动态检测PCT可判断疗效及预后。     

中性粒细胞CD64和降钙素原联合检测在新生儿细菌感染早期诊断中的价值

目的探讨血清中性粒细胞CD64和降钙素原(PCT)联合检测在新生儿细菌感染早期诊断中的价值。方法将37例细菌感染新生儿依据出院诊断分为败血症组(n=15)和一般感染组(非败血症患儿;n=22);并选取同期住院非感染新生儿作为对照组(n=21)。各组新生儿均于入院后即刻抽取静脉血,采用流式细胞术检测血清中性粒细胞CD64表达,化学发光法和免疫透射比浊法分别检测血清PCT及CRP水平。结果败血症组血清中性粒细胞CD64、PCT、CRP水平高于对照组(P0.01);一般感染组中性粒细胞CD64水平高于对照组(P0.01);败血症组血清PCT、CRP水平高于一般感染组(P0.01)。中性粒细胞CD64、PCT、CRP诊断细菌感染的曲线下面积分别为0.818、0.818、0.704,均低于中性粒细胞CD64与PCT联合诊断细菌感染的曲线下面积(0.926)。中性粒细胞CD64与PCT联合检测在早期诊断新生儿感染的灵敏度和准确度分别为97.29%和89.65%,较CRP联合中性粒细胞CD64或PCT检测的灵敏度和准确度均高,较中性粒细胞CD64、PCT及CRP单项检测的灵敏度和准确度更高。结论中性粒细胞CD64、PCT联合检测能显著提高新生儿细菌感染诊断的灵敏度及准确度,有助于早期识别细菌感染。     

不同时段血清降钙素原浓度对新生儿早发细菌感染的诊治价值

目的：评估出生早期不同时段血清降钙素原(procalcitonin,PCT)对新生儿早发细菌感染的诊断和治疗价值。方法将195例有宫内感染高危因素的新生儿根据感染结局分为细菌感染组24例及非感染组171例,测定出生2h内,6~12h,12~36h及大于48h新生儿血清PCT、C-反应蛋白(C-reactive protein,CRP)及外周血白细胞含量,分析不同时段PCT诊断早发感染的敏感度、特异度,及其对疗效的判断。结果出生2h内细菌感染组PCT、CRP及白细胞阳性率比较差异均无统计学意义(P﹥0.05);出生6~12h当PCT以2ng/ml为阈值时,其诊断细菌感染的敏感度为91.7%,特异度为86.5%,较CRP及白细胞具有更高的敏感度;出生12~36h是PCT的生理性高峰期,不同阈值的PCT均不能同时有较高的敏感度及特异度,当PCT以0.5ng/ml、2ng/ml以及10ng/ml为阈值时,其敏感度分别为100%、91.7%及75.0%,特异度分别为5.8%、53.8%及95.9%。结论出生6~12h测定PCT,并且以2ng/ml为阈值时,对诊断早发细菌感染有较高的敏感度及特异度,尽量避开PCT的生理性高峰期(出生12~36h)测定PCT浓度,该时期诊断细菌感染的PCT阈值尚需进一步探讨。     

降钙素原在新生儿感染中的应用价值

目的为进一步提高新生儿重症感染的早期诊断率 ,探讨一种快速可靠的方法。方法对以新生儿感染为诊断收入我院新生儿科 (包括NICU)的71例新生儿进行降钙素原 (PCT)的测定 ,并与C反应蛋白 (CRP)进行比较 ,将患儿分为重症感染、一般感染和非感染3组进行分析。结果重症感染组PCT阳性率89.29 % ,一般感染组PCT阳性率54.55 % ,非感染组PCT阳性率9.52 % ,重症感染组PCT阳性率明显高于其他两组 ,3组间PCT值差异有极显著性 (P<0.001)。以0.5ng/ml为临界值,PCT诊断重症感染的敏感度为89.29 %,特异度为67.44 %;以2ng/ml为临界值,诊断重症感染的敏感度为71.43,特异度为90.70 %。与CRP相比 ,PCT诊断感染特别是重症感染的敏感性、特异性更高。结论细菌感染时血清PCT水平会升高 ,特别是全身性重症细菌感染时其升高尤为明显 ,可作为新生儿感染的早期检测指标 ,与CRP相比 ,PCT较其优越性更明显 ,特别对新生儿重症感染如败血症等诊断更有价值。     

血清前降钙素在新生儿重症感染中的诊断价值

目的 探讨血清前降钙素(PCT)在新生儿重症感染中的诊断价值.方法 应用免疫荧光法对115例重症感染新生儿(细菌感染组75例,病毒感染组40例)和30例无感染征象患儿(对照组)入院时进行血清PCT测定,采用免疫散射比浊法检测CRP和WBC计数,检测结果 分为PCT<0.5 μg/L.0.5～2.0μg/L,2.0～10.0μg/L,≥10.0μg/L 4个等级,PCT0.5μg/L为阳性,2.0 μg/L,为强阳性.对明确细菌感染的新生儿复查PCT及CRP水平.结果 细菌感染组PCT阳性率为96%(72/75例).病毒感染组PCT.阳性率为35%(14/40)例),对照组PCT阳性率为6.67%(2/30例).3组间PCT阳性率两两比较,差异有显著意义(P<0.01).细菌感染组PCT强阳性率为44%(33/75例),与病毒感染组(10%)和对照组(0)比较,差异均有显著意义(Pa<0.01);病毒感染组PCT强阳性率与对照组比较,差异无显著意义(P>0.05).细菌感染组CRP阳性率明显高于病毒感染组和对照组(Pa<0.05);病毒感染组与对照组CRP比较,差异无显著意义(P>0.05).细菌感染组治疗后5例PCT≥10.0μg/L,2例死亡,3例病情恶化自动出院.结论 血清PCT是鉴别细菌感染和病毒感染、细菌感染预后判断及治疗监测的主要指标之一.     

CD64联合C-反应蛋白及降钙素原检测在新生儿败血症的临床研究

目的 研究CD64联合C-反应蛋白(C-reactive protein,CRP)及降钙素原(procalcitonin, PCT)检测对新生儿败血症临床诊断的意义.方法 选取福建医科大学附属福州市第一医院儿科2015年3月至2016年6月收治的经临床确诊为新生儿败血症的70例患儿为败血症组、35例非感染性疾病患儿为非感染组、40例健康新生儿为健康对照组.通过流式细胞仪检测各组新生儿血液CD64,全自动生化分析仪检测血清CRP和PCT,并进行对比分析.结果 败血症组新生儿全血CD64、血清CRP和PCT均显著高于非感染组和健康对照组新生儿(P<0.05);CD64、CRP和PCT联合诊断败血症的敏感性和特异性分别为97.14%和96.00%,均高于3项指标单独诊断新生儿败血症的敏感性和特异性.结论 联合检测CD64、CRP和PCT可以提高新生儿败血症诊断的特异性,为临床早期诊断提供依据.     

降钙素原在新生儿细菌感染中的诊断价值

目的探讨降钙素原（PCT）在新生儿重症感染时的诊断价值。方法将167例住院新生儿分严重感染组、一般感染组、非感染组、恢复期组4组，检测血清PCT、血清CRP、白细胞计数及分类，进行结果分析。结果以PCT≥0．5ng／ml为阳性，各组阳性：重感染组为88．00％，一般感染组为55．00％，非感染组为14．29％，恢复期组为9．52％，严感染组阳性率明显高于其他3组与3组间两两比较，差异有统计学意义（He：73．24，P〈0．00）。结论PCT可作为新生儿感染的早期检测指标，动态检测PCT可判断疗效及预后。     

降钙素原在诊断早期新生儿感染中的意义

目的 评价降钙素原(PCT)、CRP、WBC总数及杆状核细胞对早期新生儿感染诊断的价值.方法 选择本院产科出生且小于3d的因血WBC、杆状核细胞和CRP增高诊断为新生儿感染的63例新生儿为研究对象.所有患儿入院后(抗生素使用前)立即取血做血常规、血培养及CRP、PCT检查,根据PCT结果 将患儿分为PCT增高组(PCT≥2μg·L-1)和PCT正常组(PCT＜2μg·L-1),治疗后复查上述指标.结果 63例患儿血培养均阴性,入院时血WBC(29.45±9.61)×109L-1,中性粒细胞为0.7836±0.0786,杆状核细胞为0.0770±0.0377,血小板为(241.44±9.30)×109L-1.PCT增高组28例,PCT中位数为7.07(2.02,53.57)μg·L-1,PCT正常组35例,PCT中位数为0.45(0.05,1.83)μg·L-1.2组胎龄、体质量、胎心异常史、羊水污染史、胎膜早破史、母亲发热史、母亲血象增高史、入院时血WBC及杆状核均无统计学差异,PCT增高组中5例CRP增高,PCT正常组CRP均正常.2组治疗前后各感染指标比较除血小板外差异均无统计学意义,PCT增高组治疗前后血小板均高于PCT正常组(Pa＜0.01).Spearman相关分析显示PCT与WBC总数及中性粒细胞杆状核细胞、血小板、CRP均无相关性(Pa＞0.05).结论 早期新生儿轻症感染以血WBC增高及杆状核增高为主,可伴或不伴CRP增高,PCT大多正常,因此PCT对诊断早期新生儿轻症感染的意义不大.     

降钙素原及C-反应蛋白联合检测在新生儿院内感染早期诊断中的意义

目的：新生儿败血症的早期缺乏特异的临床表现,极易误诊和漏诊,本文通过对新生儿血清降钙素原(procaicltonin,PCT)和C-反应蛋白(C-reactive protein,CRP)水平进行动态监测,阐明联合应用PCT及CRP检测在新生儿院内感染早期诊断中的临床价值。方法采用回顾性分析方法,选取2013年6月至2014年8月中国医科大学附属盛京医院第一新生儿科收治的患儿111例,其中确诊败血症组37例,临床败血症组42例,对照组32例(同期住院的非感染患儿)。败血症组在感染发生时(抗生素治疗前),感染发生(抗生素治疗后)12h、24h,感染控制后3d、7d,对照组在入院后应用抗生素前分别采集血清,采用酶联荧光分析法定量测定PCT、免疫比浊法测定CRP水平。结果与对照组比较, PCT、CRP含量在确诊败血症组和临床败血症组于抗生素治疗前均明显增高(P﹤0.01)。在确诊败血症组和临床败血症组,PCT 于感染发生后12h 达峰值[分别为(15.00±15.51)ng/ml 和(17.93±13.44)ng/ml],感染控制后3d降至正常[分别为(0.49±0.47)ng/ml和(0.42±0.34)ng/ml],CRP于感染发生24h后达峰值[分别为(37.53±30.29)mg/L和(32.41±29.33)mg/L],7d后降至正常[分别为(5.72±2.98)mg/L和(5.06±3.07)mg/L]。当PCT﹥2ng/ml、CRP﹥10mg/L时准确性最好(约登指数分别为76.11%,59.45%),其敏感性分别为88.61%,75.70%;特异性分别为87.5%,83.75%;阳性预测值分别为94.59%,95.65%;阴性预测值分别为75.68%,46.15%。联合检测PCT与CRP时,各诊断效率指标均明显改善。二者受试者工作特征曲线下面积分别为0.964,0.887。结论在感染早期时,CRP和PCT均升高,当CRP﹥10mg/L,PCT﹥2ng/ml时诊断准确性好。但前者在感染后24h达峰值,7d降至正常,而后者在感染后12h达峰值,感染控制后3d恢复正常,联合检测PCT及CRP可提高检测的敏感度、特异度,准确性最佳。     

前降钙素检测在新生儿败血症中的临床应用

目的　探讨前降钙素 (PCT)监测对新生儿败血症疗效判定的临床意义。方法　入院时 ,4 8h ,1周左右对 2 0 0 1年 9月～ 2 0 0 2年 3月诊治新生儿败血症 72例进行PCT测定 ,同时行细胞计数及C反应蛋白 (CRP)检测。结果　 72例患儿入院后PCT均 >0 .5 μg/L ,阳性率 10 0 % ,PCT >10 μg/L以上 2 0例 ,血常规及CRP显示血白细胞计数升高不明显 ,而CRP在入院时 33例 (4 6 .4 % )异常 ,治疗后痊愈 70例 ,PCT均降至正常。结论　PCT在败血症早期用于监测诊断及治疗很重要 ,敏感性更高。     

Procalcitonin in children admitted to hospital with community acquired pneumonia.

AIMS: To assess the sensitivity, specificity, and predictive value of procalcitonin (PCT) in differentiating bacterial and viral causes of pneumonia. METHODS: A total of 72 children with community acquired pneumonia were studied. Ten had positive blood culture for Streptococcus pneumoniae and 15 had bacterial pneumonia according to sputum analysis (S pneumoniae in 15, Haemophilus influenzae b in one). Ten patients had Mycoplasma pneumoniae infection and 37 were infected with viruses, eight of whom had viral infection plus bacterial coinfection. PCT concentration was compared to C reactive protein (CRP) concentration and leucocyte count, and, if samples were available, interleukin 6 (IL-6) concentration. RESULTS: PCT concentration was greater than 2 microg/l in all 10 patients with blood culture positive for S pneumoniae; in eight of these, CRP concentration was above 60 mg/l. PCT concentration was greater than 1 microg/l in 86% of patients with bacterial infection (including Mycoplasma and bacterial superinfection of viral pneumonia). A CRP concentration of 20 mg/l had a similar sensitivity but a much lower specificity than PCT (40% v 86%) for discriminating between bacterial and viral causes of pneumonia. PCT concentration was significantly higher in cases of bacterial pneumonia with positive blood culture whereas CRP concentration was not. Specificity and sensitivity were lower for leucocyte count and IL-6 concentration. CONCLUSIONS: PCT concentration, with a threshold of 1 microg/l is more sensitive and specific and has greater positive and negative predictive values than CRP, IL-6, or white blood cell count for differentiating bacterial and viral causes of community pneumonia in untreated children admitted to hospital as emergency cases.     

������ԭ�������ط��Թؽ�������е��ٴ�����

??Abstracts?? Objective To study the relationship between procalcitonin ??PCT?? and the pathogenesis of juvenile idiopathic arthritis ??JIA??. Methods We tested the values of PCT and CRP of 150 JIA cases. To find the diagnostic value of PCT and CRP in JIA with bacterial infection??we compared the clinical value of PCT and that of CRP?? including sensitivity?? specificity??positive predictive value and negative predictive value. Besides?? we tested the level of PCT in various patterns of JIA. Results PCT value in cases of JIA with bacterial infection was ??3.56±0.84???? which was markedly higher than that in JIA cases with virus infection??0.05±0.01????P??0.05??and that in JIA disease activited without infection group??0.19±0.01????P??0.05??and that in control group .However?? there wasn’t significant difference between JIA cases with virus infection and control group. If we considered diagnostic positive threshold of JIA cases without virus infection as PCT≥0.5 μg/L??then its sensitivity?? specificity?? positive predictive value??negative predictive value ?? positive likelihood ratio and negative likelihood ratio were 76.2%??87.6%??50.0%??95.8%??6.14 and 0.27?? respectively. In 98.99% of the JIA activity without infection group PCT value was??0.5 μg/L??the median was 0.2 μg/L. In 66.7% of the JIA activity without infection group??PCT??0.1 μg/L. Conclusion Testing PCT value has significant role in diagnosing JIA with bacterial infection ?? and the prediction value is superior to CRP infection. It can be considered to recommend PCT??0.5 μg/L as the diagnosis of JIA infection in patients with critical value.     

Procalcitonin serum levels in perinatal bacterial and fungal infection of preterm infants

AIM: To determine reference values for procalcitonin (PCT) and C-reactive protein (CRP) for gestational age and to use these parameters as diagnostic markers of perinatal bacterial and fungal infection. METHODS: PCT and CRP serum levels were measured in a case-control study in a group of 35 low birthweight infants (< 34 wk of gestation). 27 babies (77%) had clinical signs of infection confirmed by positive blood cultures and were compared to 8 (23%) uninfected matched patients. Seventeen (63%) of them had bacterial infection and 10 (37%) had fungal infection (Candida). Serum PCT (Brahms Diagnostika) and CRP (Immunoassay Vitros 950) were measured serially at 3, 7 and 10d of life. RESULTS: At any time, PCT and CRP levels were significantly higher in neonates with perinatal infection (p < 0.05) (> 0.7 ng ml(-1) and > 1 mg dl(-1) respectively). PCT showed a more rapid response to infection (9.3 +/- 1.5 ng ml(-1)). especially to bacterial infection (10.8 +/- 1.4 ng ml(-1)), than CRP (1.5 +/- 0.5 mg dl(-1)) (sensitivity 99% vs 88%). Lower sensitivity was noted for both parameters. PCT and CRP, to follow babies with fungal infection (6.7 +/- 0.8 ng ml(-1) and 0.9 +/- 0.7 mg dl(-1), respectively) (sensitivity 77% vs 58%). CONCLUSION: This study gives PCT reference values in preterm babies with perinatal infection. In these babies, PCT seems to be more sensitive than CRP as a diagnostic marker of infection. Both parameters can be used alone or in combination for a better identification and follow-up of bacterial and fungal infection during the perinatal period.     

Procalcitonin in children admitted to hospital with community acquired pneumonia

AIMS—To assess the sensitivity, specificity, and predictive value of procalcitonin (PCT) in differentiating bacterial and viral causes of pneumonia.METHODS—A total of 72 children with community acquired pneumonia were studied. Ten had positive blood culture for Streptococcus pneumoniae and 15 had bacterial pneumonia according to sputum analysis (S pneumoniae in 15, Haemophilus influenzae b in one). Ten patients had Mycoplasma pneumoniae infection and 37 were infected with viruses, eight of whom had viral infection plus bacterial coinfection. PCT concentration was compared to C reactive protein (CRP) concentration and leucocyte count, and, if samples were available, interleukin 6 (IL-6) concentration.RESULTS—PCT concentration was greater than 2 µg/l in all 10 patients with blood culture positive for S pneumoniae; in eight of these, CRP concentration was above 60 mg/l. PCT concentration was greater than 1 µg/l in 86% of patients with bacterial infection (including Mycoplasma and bacterial superinfection of viral pneumonia). A CRP concentration of 20 mg/l had a similar sensitivity but a much lower specificity than PCT (40% v 86%) for discriminating between bacterial and viral causes of pneumonia. PCT concentration was significantly higher in cases of bacterial pneumonia with positive blood culture whereas CRP concentration was not. Specificity and sensitivity were lower for leucocyte count and IL-6 concentration.CONCLUSIONS—PCT concentration, with a threshold of 1 µg/l is more sensitive and specific and has greater positive and negative predictive values than CRP, IL-6, or white blood cell count for differentiating bacterial and viral causes of community pneumonia in untreated children admitted to hospital as emergency cases.     

Role of procalcitonin, C-reactive protein, interleukin-6, interleukin-8 and tumor necrosis factor-alpha in the diagnosis of neonatal sepsis

Diagnosis of neonatal sepsis may be difficult because clinical presentations are often nonspecific, bacterial cultures are time-consuming and other laboratory tests lack sensitivity and specificity. In this study, we aimed to investigate the role of procalcitonin (PCT), C-reactive protein (CRP), interleukin (IL)-6, IL-8 and tumor necrosis factor-alpha (TNF-alpha) in establishing the diagnosis and evaluating the prognosis of neonatal sepsis. Twenty-six neonates with blood-culture positivity and clinical sepsis, hospitalized for clinical suspicion of neonatal sepsis in neonatal intensive care units of Balcali Hospital, Cukurova University and Adana State Hospital between May 2000 and January 2001 (Group I) and 29 healthy neonates followed at the neonatal units and outpatient clinics of these hospitals (Group II) in the same period were studied. Among the septic neonates, 13 had early-onset (Group Ia) and 13 had late-onset (Group Ib) neonatal sepsis, while 14 of the healthy neonates had perinatal risk factors (Group IIa) and 15 of them had no risk factors (Group IIb). The demographic and clinical characteristics of the septic and healthy neonates were recorded, blood samples for determining serum PCT, CRP, IL-6, IL-8 and TNF-alpha were collected from the healthy and the septic neonates before starting treatment, and these investigations were repeated on the 3rd and 7th days of treatment. In this study, it was found that: (a) pre-treatment mean serum PCT, CRP, IL-6, IL-8 and TNF-alpha levels were significantly higher in the septic neonates than in the healthy ones, (b) compared with the pre-treatment values, serum PCT, IL-6 and TNF-alpha had progressively decreased on the 3rd and 7th days of the treatment in the 17 recovered patients, though they progressively increased in nine patients who died during treatment, (c) the area under the receiver operating characteristic (ROC) curve (AUC) for PCT, TNF-alpha, IL-6, CRP, and IL-8 were 1.00, 1.00, 0.97, 0.90 and 0.68, respectively. For the cut-off value of PCT > or = 0.34 ng/ml, the test was found to have a sensitivity of 100%, specificity of 96.5%, positive predictive value of 96.2%, negative predictive value of 100% and diagnostic efficacy of 98.3% for bacterial sepsis in neonates. For the cut-off value of TNF-alpha > or = 7.5 pg/ml, sensitivity, specificity, positive predictive value, negative predictive value and diagnostic efficacy were found to be 100%, 96.6%, 96.2%, 96.5% and 98.3%, respectively. It was detected that sensitivity, specificity and diagnostic efficacy values were lower for IL-6, CRP and IL-8. We conclude that PCT and TNF-alpha are the best markers in the diagnosis of neonatal sepsis, and these markers are also valuable in following the effectiveness of treatment and determining the prognosis of the disease.     

Procalcitonin, IL-6, IL-8, IL-1 receptor antagonist and C-reactive protein as identificators of serious bacterial infections in children with fever without localising signs

Fever without localising signs in very young children remains a diagnostic problem. Until present, a clinical scoring system combined with leucocyte count, urine analysis and determination of CRP are recognised as being helpful to identify patients at risk of serious bacterial illness. In this study we asked the question whether the determination of procalcitonin (PCT), interleukin (IL)-6, IL-8 and interleukin-1 receptor antagonist (IL-1Ra) was superior to these commonly used markers for the prediction of a serious bacterial infection (SBI). Children, 7 days to 36 months of age, with a rectal temperature above 38 °C and without localising signs of infection were prospectively enrolled. For each infant, we performed a physical examination, a clinical score according to McCarthy, a complete white cell count, an urine analysis and a determination of CRP. We further determined PCT, IL-6, IL-8, and IL-1Ra concentrations and compared their predictive value with those of the usual management of fever without localising signs. Each infant at risk of SBI had blood culture, urine and cerebrospinal fluid cultures when indicated, and received antibiotics until culture results were available. A total of 124 children were included of whom 28 (23%) had SBI. Concentrations of PCT, CRP and IL-6 were significantly higher in the group of children with SBI but IL-8 and IL-1Ra were comparable between both groups. PCT showed a sensitivity of 93% and a specificity of 78% for detection of SBI and CRP had a sensitivity of 89% and a specificity of 75%. Conclusion Compared to commonly used screening methods such as the McCarthy score, leucocyte count and other inflammatory markers such as interleukin-6, interleukin-8 and interleukin-1 receptor antagonist, procalcitonin and C-reactive protein offer a better sensitivity and specificity in predicting serious bacterial infection in children with fever without localising signs. Received: 29 May 2000 and in revised form: 15 September 2000 / Accepted: 25 September 2000     

Diagnostic markers of infection: comparison of procalcitonin with C reactive protein and leucocyte count.

BACKGROUND: Procalcitonin has been advocated as a marker of bacterial infection. OBJECTIVE: To evaluate diagnostic markers of infection in critically ill children, comparing procalcitonin with C reactive protein and leucocyte count in a paediatric intensive care unit (PICU). METHODS: Procalcitonin, C reactive protein, and leucocyte count were measured in 175 children, median age 16 months, on admission to the PICU. Patients were classified as: non-infected controls (43); viral infection (14); localised bacterial infection without shock (25); bacterial meningitis/encephalitis (10); or septic shock (77). Six children with "presumed septic shock" (without sufficient evidence of infection) were analysed separately. Optimum sensitivity, specificity, predictive values, and area under the receiver operating characteristic (ROC) curve were evaluated. RESULTS: Admission procalcitonin was significantly higher in children with septic shock (median 94.6; range 3.3-759.8 ng/ml), compared with localised bacterial infection (2.9; 0-24.3 ng/ml), viral infection (0.8; 0-4.4 ng/ml), and non-infected controls (0; 0-4.9 ng/ml). Children with bacterial meningitis had a median procalcitonin of 25.5 (7.2-118.4 ng/ml). Area under the ROC curve was 0.96 for procalcitonin, 0.83 for C reactive protein, and 0.51 for leucocyte count. Cut off concentrations for optimum prediction of septic shock were: procalcitonin > 20 ng/ml and C reactive protein > 50 mg/litre. A procalcitonin concentration > 2 ng/ml identified all patients with bacterial meningitis or septic shock. CONCLUSION: In critically ill children the admission procalcitonin concentration is a better diagnostic marker of infection than C reactive protein or leucocyte count. A procalcitonin concentration of 2 ng/ml might be useful in differentiating severe bacterial disease in infants and children.