Serum Procalcitonin


Differentiation of Bacterial Community-Acquired Pneumonia (CAP) from Other Etiologies of Pneumonia (see Pneumonia, Pneumonia)

  • Rationale: serum procalcitonin is the peptide precursor of calcitonin which is released by parenchymal cells in response to bacterial toxins
    • Serum Procalcitonin is Elevated in Bacterial Infections
    • Serum Procalcitonin is Downregulated in Viral Infections
  • Clinical Efficacy
    • Systematic Review of the Utility of Serum Procalcitonin in the Diagnosis of Bacterial Pneumonia (Cochrane Database Syst Rev, 2012) [MEDLINE]
      • Serum Procalcitonin Use to Guide Initiation and Duration of Antibiotic Use Did Not Increase Mortality Rates or Treatment Failures in Any Treatment Setting
      • Serum Procalcitonin Decreased Antibiotic Consumption
      • Further Research is Required to Determine the Safety of Serum Procalcitonin-Guided Therapy in the ICU Setting

Differentiation of Bacterial Hospital-Acquired Pneumonia (HAP)/Ventilator-Associated Pneumonia (VAP) from Other Etiologies of Pneumonia (see Pneumonia, Pneumonia)

  • Recommendations (Infectious Diseases Society of America, IDSA/American Thoracic Society, ATS 2016 Clinical Practice Guidelines for the Management of HAP/VAP (Clin Infect Dis, 2016) [MEDLINE]
    • For Patients with Suspected HAP/VAP, Clinical Criteria Alone Should Be Used, Rather than Clinical Criteria and Serum Procalcitonin (Strong Recommendation, Moderate-Quality Evidence)

Differentiation of Parapneumonic Pleural Effusions from Effusions of Other Etiologies

  • Clinical Efficacy
    • Study of Serum Procalcitonin in Differentiating Parapneumonic Effusion from Malignant/Tuberculous Effusion (Clin Biochem, 2013) [MEDLINE]
      • Serum Procalcitonin >0.18 ng/mL: 83.3% sensitivity/81.0% specificity in determining if a pleural effusion has a bacterial infectious etiology
      • Serum Procalcitonin Performed Better than Pleural Fluid Procalcitonin


  • Procalcitonin is a Precursor of Calcitonin that is Constitutively Secreted by C Cells in the Thyroid Gland and K Cells in the Lung
    • In Healthy Patients, Procalcitonin is Normally Undetectable (<0.01 ng/mL)
    • When Stimulated by the Presence of Endotoxin, Procalcitonin is Rapidly Produced by Parenchymal Tissues Throughout the Body
    • Procalcitonin Has Been Observed in a Variety of Bacterial Infections
    • Less Commonly, Procalcitonin May Increase in Response to Sterile Inflammation or Viral Infection (Lancet, 1993) [MEDLINE]


  • High serum procalcitonin concentrations in patients with sepsis and infection. Lancet 1993; 341:515–8 [MEDLINE]
  • Procalcitonin to initiate or discontinue antibiotics in acute respiratory tract infections. Cochrane Database Syst Rev. 2012 Sep 12;(9):CD007498. doi: 10.1002/14651858.CD007498.pub2 [MEDLINE]
  • Procalcitonin as a diagnostic marker in differentiating parapneumonic effusion from tuberculous pleurisy or malignant effusion. Clin Biochem. 2013;46(15):1484 [MEDLINE]
  • Biomarkers: what is their benefit in the identification of infection, severity assessment, and management of community-acquired pneumonia? Infect Dis Clin North Am. 2013 Mar;27(1):19-31. Epub 2012 Dec 6 [MEDLINE]
  • Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis. 2016 Sep 1;63(5):e61-e111. doi: 10.1093/cid/ciw353. Epub 2016 Jul 14 [MEDLINE]