Lab

Procalcitonin

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Procalcitonin, proCT

  • Indication
  1. Marker of Bacterial Infection and Sepsis
  2. Specific protocols (e.g. Step-By-Step Protocol for Febrile Infants)
  • Physiology
  1. Peptide produced in the Thyroid, lung and Intestine
  2. Calcitonin precursor (involved in Calcium Homeostasis)
  3. Remains at low levels when well
  4. Increases in inflammatory states, rising within 4 hours of infection onset and peaking at 12 to 48 hours
    1. Postulated to increase markedly, and selectively in Bacterial Infection
    2. Postulated to allow for monitoring treatment response due to Procalcitonin short Half-Life
  5. Contrast with Interferon gamma, which increases in Viral Infections and decreases Procalcitonin
  • Interpretation
  1. Procalcitonin level <0.05: Normal
  2. Procalcitonin level <0.25: Bacterial Sepsis unlikely
  3. Vijayan (2017) J Intensive Care 5:51 +PMID: 28794881 [PubMed]
  • Efficacy
  • Adults
  1. Mediocre efficacy in Sepsis diagnosis
    1. Test Sensitivity: 77%
    2. Test Specificity: 79%
    3. Wacker (2013) Lancet Infect Dis 13(5): 426-35 +PMID: 23375419 [PubMed]
  2. Low efficacy in Bacterial Pneumonia diagnosis
    1. Test Sensitivity: 55%
    2. Test Specificity: 76%
    3. Maisel (2012) Eur J Heart Fail 14(3): 278-86 +PMID: 22302662 [PubMed]
  3. Worse outcomes in ICU when Procalcitonin was used to direct Antibiotic management
    1. Bouadma (2010) Lancet 375(9713): 463-74 +PMID: 20097417 [PubMed]
  4. May allow shortening of Antibiotic course in Sepsis and respiratory infections without adversely affecting outcomes
    1. Elnajdy (2022) Infect Dis 54(6):387-402 +PMID: 35175169 [PubMed]
  • Efficacy
  • Children
  1. See Serious Bacterial Infection in Children (Occult Bacteremia)
  2. Serious Bacterial Infection in Neonatal Fever
    1. Test Sensitivity: 74%
    2. Test Specificity: 78%
    3. Milcent (2016) JAMA Pediatr 170(1): 62-9 [PubMed]
  3. Variable efficacy, although initial studies had very high accuracy in septic children
    1. Test Sensitivity: 26-55% for Bacterial Infection
    2. Test Specificity: 75 to 82% for Bacterial Infection
  4. Interpretation
    1. PCT <0.5 ng/ml has a Negative Predictive Value for serious Bacterial Infection of 90%
    2. PCT >0.6 (and WBC >19k, blasts >1.8k, Neutrophils >13k) suggests serious Bacterial Infection
  5. References
    1. Gendrel (1996) J Pediatr 128:570-3 [PubMed]
    2. Olaciregui (2009) Arch Dis Child 94(7): 501-5 +PMID:19158133 [PubMed]
    3. Mahajan (2014) Acad Emerg Med 21(2): 171-9 +PMID:24673673 [PubMed]
  • References
  1. Orman, Herbert, Spiegel in Herbert (2016) EM:Rap 16(10):12-3
  2. Morgenstern in Swadron (2022) EM:Rap 22(9): 4-6
  3. Dolatabadi (2015) Niger Med J 56(1):17-22 +PMID:25657488 [PubMed]