Lab

Procalcitonin

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Procalcitonin, proCT

  • Indication
  1. Marker of Bacterial Infection and Sepsis
  • Physiology
  1. Peptide produced in the Thyroid, lung and intestin
  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 in Bacterial Infection
    2. Postulated to allow for monitoring treatment response due to Procalcitonin short half-life
  • 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 Pneumonia diagnosis
    1. Maisel (2013) Ear 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]
  • Efficacy
  • Children
  1. See Serious Bacterial Infection in Children (Occult Bacteremia)
  2. 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
  3. 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
  4. 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. Dolatabadi (2015) Niger Med J 56(1):17-22 +PMID:25657488 [PubMed]