Procalcitonin - American Medical Technologists

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Procalcitonin
Over the past two decades, the body of literature
on the clinical usefulness of procalcitonin (PCT)
in adults has grown rapidly.
Although this approach has led to increased
insight, it has also prompted debate regarding
its potential use in diagnosis and management
of severe infection.
Clinicians, however, are less familiar
with the use of procalcitonin.
Procalcitonin
• Elevation in the serum concentration of PCT is associated with
systemic infection. This association has led to the proposed
use of PCT as a novel biomarker of bacterial 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?
• 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.
• PCT has a slightly better ability to exclude the diagnosis of
sepsis.
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Ninety-four patients with consecutive trauma >or=16 years who were admitted to
the ICU for an expected stay of >24 hours.
PCT and CRP were collected at admission and every day thereafter. The American
College of Chest Physicians/Society of Critical Care Medicine Consensus
Conference definition was used to identify sepsis criteria. The Sequential Organ
Failure Assessment score was used to describe the severity of organ dysfunction
Patients with trauma presented an early and significant increase in PCT at the
moment of septic complications compared with concentrations measured 1 day
before the diagnosis of sepsis: 0.85 vs. 3.32 ng/mL for PCT (p < 0.001) and 135 vs.
175 mg/L for CRP (p = not significant). The areas under the respective curve at
admission in the diagnosis of sepsis were 0.787 for PCT and CRP and 0.489 ,
CONCLUSION:
PCT plasma marks possible septic complication during systemic inflammatory
response syndrome after major trauma.
In addition, high PCT concentration at admission after trauma in ICU patients
indicates an increased risk of septic complications.
Diagnostic accuracy of PCT, WBC and,
CRP for suspected acute appendicitis
• RESULTS:
• Seven qualifying studies (1011 suspected cases, 636
confirmed) from seven countries were identified. ROC curve
analysis showed that CRP had the highest accuracy area under
ROC curve 0·75, followed by WBC 0·72, and PCT 0·65. PCT
was found to be more accurate in diagnosing complicated
appendicitis, with a pooled sensitivity of 62 per cent and
specificity of 94 per cent.
• CONCLUSION:
• PCT has little value in diagnosing acute appendicitis, with
lower diagnostic accuracy than CRP and WBC. However, PCT
has greater diagnostic value in identifying complicated
appendicitis.
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Seven qualifying studies (1011 suspected cases, 636 confirmed) from seven
countries were identified. Bivariable pooled sensitivity and specificity were 33 (95
per cent confidence interval (c.i.) 21 to 47) and 89 (78 to 95) per cent respectively
for PCT, 57 (39 to 73) and 87 (58 to 97) per cent for CRP, and 62 (47 to 74) and 75
(55 to 89) per cent for WBC. ROC curve analysis showed that CRP had the highest
accuracy (area under ROC curve 0·75, 95 per cent c.i. 0·71 to 0·78), followed by
WBC (0·72, 0·68 to 0·76) and PCT (0·65, 0·61 to 0·69). PCT was found to be more
accurate in diagnosing complicated appendicitis, with a pooled sensitivity of 62 (33
to 84) per cent and specificity of 94 (90 to 96) per cent.
CONCLUSION:
PCT has little value in diagnosing acute appendicitis, with lower diagnostic
accuracy than CRP and WBC. However, PCT has greater diagnostic value in
identifying complicated appendicitis. Given the imperfect accuracy of these three
variables, new markers for improving medical decision-making in patients with
suspected appendicitis are highly desirable.
Copyright © 2012 British Journal of Surgery Society Ltd. Published by John Wiley &
Sons, Ltd.
Pediatric appendicitis
• METHODS:
• Subjects aged 1 to 18 years presenting with abdominal pain
suspicious for acute appendicitis were enrolled.
• RESULTS:
• Two hundred nine subjects (59% male, 41% female) were enrolled
over 6 months. One hundred fifteen subjects were histologically
diagnosed with appendicitis; 94 subjects did not have appendicitis
and were used as controls. Mean values of WBC, CRP, PCT, and
absolute neutrophil count in subjects with definitive appendicitis
were significantly higher than in subjects with no definitive
appendicitis. D-Lactate levels were noncorrelative.
• CRP with WBC is useful in distinguishing appendicitis from other
diagnoses in pediatric subjects presenting to the ED. White blood cell
count greater than >12 cells × 1000/mm(3) and CRP greater than 3
mg/dL increases the likelihood of appendicitis. D-Lactate is not a
useful laboratory adjunct. dp notes the fact that PCT is missing
Suspected Appendicitis
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A prospective observational study was carried out in the emergency department of a
university hospital. Adult patients who presented to the ED with clinically suspected
appendicitis were enrolled. Each patient underwent serum PCT, CRP, and Alvarado score
evaluation on admission. The results of these three measurements were analyzed in relation
to the final diagnosis determined by histopathological findings or compatible computed
tomography findings.
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Of the 214 study patients, 113 (52.8 %) had a confirmed diagnosis of appendicitis and 58 had
complicated appendicitis. For the diagnosis of appendicitis, the area under the receiving
operating characteristic (ROC) curve is 0.74 for Alvarado score, 0.69 for PCT, and 0.61 for CRP.
Overall, the Alvarado score has the best discriminative capability among the three tested
markers. We adopted two cutoff point approaches to harness both ends of the diagnostic
value of a biomarker. PCT levels were significantly higher in patients with complicated
appendicitis. For diagnosis of complicated appendicitis, a cutoff value of 0.5 ng/mL had a
sensitivity of 29 % and a specificity of 95 %, while a cutoff value of 0.05 ng/ml had a
sensitivity of 85 % and a specificity of 30 % in diagnosing complicated appendicitis. For those
with a PCT value in the gray zone, clinical findings may play a more important role.
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The study does not support the hypothesis that PCT may be useful for screening ED patients
for appendicitis. However, determination of the PCT level may be useful for risk assessment
of ED patients with suspected complicated appendicitis.
Discriminative value of PCT, interleukin-6 (IL-6),
and CRP for suspected sepsis.
• Of 336 enrolled subjects, 60% had definite infection, 13% possible
infection, and 27% no infection. Of those with infection, 202 presented
with sepsis, 28 with severe sepsis, and 17 with septic shock. Overall, 21%
of subjects were septicemic. PCT, IL6, and CRP levels were higher in
septicemia (median PCT 2.3 vs. 0.2 ng/mL; IL-6 178 vs. 72 pg/mL; CRP 106
vs. 62 mg/dL; p < 0.001). Biomarker concentrations increased with
likelihood of infection and sepsis severity. Using receiver operating
characteristic analysis, PCT best predicted septicemia (0.78 vs. IL-6 0.70
and CRP 0.67), but CRP better identified clinical infection (0.75 vs. PCT
0.71 and IL-6 0.69). A PCT cutoff of 0.5 ng/mL had 72.6% sensitivity and
69.5% specificity for bacteremia, as well as 40.7% sensitivity and 87.2%
specificity for diagnosing infection. no biomarker independently predicted
discharge to a higher level of care.
• In adult emergency department patients with suspected sepsis, PCT, IL-6,
and CRP highly correlate with several infection parameters, but are
inadequate at discriminating and cannot be used independently as
diagnostic tools.
WBC, CRP & PCT
• A total of 10 studies looking into PCT tests and 8 studies looking into
CRP tests were included in the final analysis. The prevalence of
bacterial sepsis was 304 of 1031 (29.5%) in PCT studies and 741 of
1316 (56.3%) in CRP studies. In terms of area under the receiver
operating characteristic curve, PCT had comparable discrimination to
CRP (area under the curve: 0.75 versus 0.74). PCT was not as
sensitive as the CRP test. The pooled sensitivity of PCT was 0.59 as
compared with 0.75 for CRP. PCT was more specific than sensitive
whereas CRP was more sensitive than specific in this population. The
pooled specificity was 0.76 for PCT and 0.62 for CRP. PCT had greater
likelihood ratio positive (2.50) making it the better rule-in test.
• Of three markers potentially useful for diagnosing bacterial sepsis in
children with fever and neutropenia, PCT had comparable diagnostic
accuracy to CRP.
Serum PCT as a diagnostic test
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for sepsis, severe sepsis, or septic shock in adults in intensive care units or after
surgery or trauma, alone and compared with CRP. To draw and compare the
summary receiver operating characteristics curves for procalcitonin and C-reactive
protein from the literature.
Thirty-three studies fulfilled inclusion criteria (3,943 patients, 1,828 males, 922
females; mean age: 56.1 yrs; 1,825 patients with sepsis, severe sepsis, or septic
shock; 1,545 with only systemic inflammatory response syndrome); Global
mortality rate was 29.3%.
Global odds ratios for diagnosis of infection complicated by systemic inflammation
were 15.7 for the 25 studies (2,966 patients) using procalcitonin and 5.4 for the 15
studies (1,322 patients) using CRP. The summary receiver operating characteristics
curve for procalcitonin was better than for CRP. In the 15 studies using both
markers, the Q* was significantly higher for procalcitonin than for C-reactive
protein (0.78 vs. 0.71, p = .02), the former test showing better accuracy.
Procalcitonin represents a good biological diagnostic marker for sepsis, severe
sepsis, or septic shock, difficult diagnoses in critically ill patients. Procalcitonin is
superior to C-reactive protein. Procalcitonin should be included in diagnostic
guidelines for sepsis and in clinical practice in intensive care units.
In Summary
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Procalcitonin has a slightly better ability to exclude the diagnosis of sepsis.
PCT plasma marks possible septic complications during systemic inflammatory
response syndrome after major trauma.
High PCT concentration at admission after trauma in ICU patients indicates an
increased risk of septic complications
PCT has little value in diagnosing acute appendicitis, with lower diagnostic
accuracy than CRP and WBC. PCT has greater diagnostic value in identifying
complicated appendicitis.
Of three markers potentially useful for diagnosing bacterial sepsis in children with
fever and neutropenia, PCT had comparable diagnostic accuracy to CRP.
PCT represents a good biological diagnostic marker for sepsis, severe sepsis, or
septic shock, difficult diagnoses in critically ill patients. PCT is superior to Creactive protein. PCT should be included in diagnostic guidelines for sepsis and in
clinical practice in intensive care units.
Clinicians, however, are less familiar with the use of PCT.
You cannot bill for this to detect sepsis

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