Serum Procalcitonin testing in Medical Admissions ( for adults only ) - Protocol for

Publication: 09/06/2017  
Next review: 14/10/2023  
Clinical Guideline
ID: 5057 
Approved By: Improving Antimicrobial Prescribing Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2020  


This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Protocol for Serum Procalcitonin testing in Medical Admissions (for adults only).  


Back to top


Procalcitonin (PCT) is a protein produced in the C-cells of the thyroid gland in levels not normally detectable in the blood. However, during bacterial infection, toxins and cytokines stimulate production of PCT in other cells, leading to rapid increase in plasma levels in around 3-4 hours. It is therefore a sensitive and specific biomarker of bacterial infection.  It has a short half-life of around 24 hours and is not dependent on renal function.

PCT has been used to differentiate bacterial infection from viral infection, fungal infection, autoimmune disease and other causes of SIRS.  Sensitivity and specificity vary between infection site, patient group and cut-off level.  Use of PCT in acute medical patients where bacterial infection was suspected has been shown to safely reduce antibiotic use, without resulting in increases in mortality or clinical failure8. Use of PCT in acute respiratory infection has been shown to be associated with lower mortality, lower antibiotic consumption and lower rates of antimicrobial side effects9.

In patients outside of the critical care setting, there is insufficient evidence to recommend the use of serial procalcitonin measurements to guide antibiotic duration. For patients in critical care, please refer to the “Enhanced Antimicrobial Stewardship with the introduction of Procalcitonin to guide antibiotic duration in Adult Critical Care” guideline (

Back to top

Indications for testing

PCT levels are used to guide antibiotic initiation in the following situations;

  • Infection is suspected but not confirmed and the criteria for sepsis are not met
  • Patients with suspected COVID-19, community acquired or healthcare associated pneumonia
  • Initiation or discontinuation of antibiotics is being considered
  • On advice from a Microbiologist or Infectious Diseases Specialist

Procalcitonin testing should not be used;

  • Where bacterial infection is highly likely or proven and antibiotics are indicated regardless of PCT result
  • Patients who meet sepsis criteria
  • Patients with significant positive cultures
  • Severely immunocompromised patients
  • Patients with cystic fibrosis, bronchiectasis or active tuberculosis

Procalcitonin levels will be increased in the following conditions and therefore should not be used to guide antibiotic therapy;

  • Surgery within previous 3 days
  • Treatment that acts upon the pro-inflammatory CK cascade (OKT3, injection therapy TNFα, IL-2 and anti-lymphocyte globulins)
  • Some cancers; medullary CT-cell cancers of the thyroid, pulmonary small-cell carcinoma and bronchial carcinoma
  • Prolonged cardiogenic shock or haemorrhage
  • Severe hepatic dysfunction
  • Rhabdomyolysis

There is insufficient evidence for use of PCT monitoring in pregnant women so testing is not recommended.

Back to top


Blood should be sent in a yellow-top tube to biochemistry.  Turn-around time is expected to be within 6 hours.  The request for PCT may be able to be ‘added-on’ to samples taken within 6 hours dependent upon laboratory capacity. Tests cost ~£14 each.


Record: 5057
Clinical condition:
Target patient group:
Target professional group(s): Secondary Care Doctors
Adapted from:

Evidence base

Adapted from Royal Hampshire Protocol written by K. Saad et al.

  1. Prkno et al. Procalcitonin-guided therapy in intensive care unit patients with severe sepsis and septic shock--a systematic review and meta-analysis.
  2. Lin C, Pang Q. Meta-analysis and systematic review of procalcitonin-guided treatment in acute exacerbation of chronic obstructive pulmonary disease. Clin Respir J. 2016;22.
  3. Vikse. Int J Infect Dis 2015;38:68-76Diagnostic Accuracy of Procalcitonin in Bacterial Meningitis Versus Nonbacterial Meningitis: A Systematic Review and Meta-Analysis. Medicine (Baltimore). 2016 Mar;95(11).
  4. Hoeber et al. The diagnostic accuracy of procalcitonin for bacteraemia: a systematic review and meta-analysis. Clin Microbiol Infect. 2015 May;21(5):474-81.
  5. Lee et al. Diagnostic value of procalcitonin for bacterial infection in elderly patients - a systematic review and meta-analysis. Int J Clin Pract. 2013 Dec;67(12):1350-7.
  6. Wu et al. Use of serum procalcitonin to detect bacterial infection in patients with autoimmune diseases: a systematic review and meta-analysis. Arthritis Rheum. 2012 Sep;64(9):3034-42.
  7. Branche et al Serum procalcitonin and viral testing to guide antibiotic use for respiratory infections in hospitalized adults: a randomized trial J Infect Dis. 2015 212(11):1692-700
  8. Andriolo_BNG, Andriolo_RB, Salomão_R, Atallah_ÁN. Effectiveness and safety of procalcitonin evaluation for reducing mortality in adults with sepsis, severe sepsis or septic shock.
    Cochrane Database of Systematic Reviews 2017, Issue 1. Art. No.: CD010959.
  9. Schuetz  P, Wirz  Y, Sager  R, Christ‐Crain  M, Stolz  D, Tamm  M, Bouadma  L, Luyt  CE, Wolff  M, Chastre  J, Tubach  F, Kristoffersen  KB, Burkhardt  O, Welte  T, Schroeder  S, Nobre  V, Wei  L, Bucher  HCC, Bhatnagar  N, Annane  D, Reinhart  K, Branche  A, Damas  P, Nijsten  M, de Lange  DW, Deliberato  RO, Lima  SSS, Maravić‐Stojković  V, Verduri  A, Cao  B, Shehabi  Y, Beishuizen  A, Jensen  JUS, Corti  C, Van Oers  JA, Falsey  AR, de Jong  E, Oliveira  CF, Beghe  B, Briel  M, Mueller  B. Procalcitonin to initiate or discontinue antibiotics in acute respiratory tract infections. Cochrane Database of Systematic Reviews 2017, Issue 10. Art. No.: CD007498. DOI:1002/14651858.CD007498.pub3

Approved By

Improving Antimicrobial Prescribing Group

Document history

LHP version 1.0

Related information

Not supplied

Equity and Diversity

The Leeds Teaching Hospitals NHS Trust is committed to ensuring that the way that we provide services and the way we recruit and treat staff reflects individual needs, promotes equality and does not discriminate unfairly against any particular individual or group.