Lab Test


Procalcitonin, Plasma

Test Codes


Specimen Collection Criteria

Collect: One Light Green-top PST tube (Lithium Heparin plasma gel separator tube). (Minimum Whole Blood: 2.0 mL)

Do NOT use Gold-top Serum Separator (SST) tubes, Dark Green-top Lithium or Sodium Heparin tubes, Red-top serum tubes, or Lavender-top EDTA tubes.

Physician Office/Draw Specimen Preparation

Invert PST tubes 8 times for proper mixing of heparin anticoagulant, then centrifuge immediately to separate plasma from cells, 1300 x g for 10 minutes (e.g., Drucker Horizon mini E centrifuge). Refrigerate (2-8°C or 36-46°F) the centrifuged PST tube. (Minimum: 1.0 mL plasma)

Preparation for Courier Transport

Transport: Centrifuged PST tube, refrigerated (2-8°C or 36-46°F). (Minimum: 1.0 mL plasma)

Rejection Criteria

  • Light Green-top PST tubes with plasma not separated from cells within two hours of collection.
  • Specimens collected in inappropriate collection tubes.
  • Specimens not collected and processed as indicated. 

In-Lab Processing

Centrifuge PST tubes to separate plasma from cells. Centrifuge specimens at 1300 x g for 5 minutes. Specimens should be free of particulate matter. Deliver immediately to the appropriate testing station.


Specimen Stability for Testing:

Centrifuged PST Tubes
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 48 hours
Frozen (-20°C/-4°F or below): Unacceptable

Plasma Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 48 hours
Frozen (-20°C/-4°F or below): 8 weeks

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Grosse Pointe Chemistry Laboratory
Royal Oak Automated Chemistry Laboratory
Troy Chemistry Laboratory


Sunday – Saturday.
Results available within 24 hours. 

Reference Range

Less than or equal to 0.25 ng/mL.

Test Methodology

Chemiluminescence Immunoassay.


If using as an aid in deciding on whether or not to start antibiotics for lower respiratory tract infections, providers should use the following guidance:

  • PCT < 0.1 ng/mL – antibiotics strongly discouraged
  • PCT 0.1-0.24 ng/mL – antibiotics discouraged
  • PCT 0.25-0.5 ng/mL – antibiotics encouraged
  • PCT > 0.5 ng/mL – antibiotics strongly encouraged

If using as an aid in deciding on whether or not to discontinue antibiotics for suspected/confirmed sepsis, providers should use the following guidance:

  • PCT ≤ 0.5 ng/mL or > 80% decrease from peak/baseline value – antibiotics discouraged
  • PCT > 0.5 and < 80% decrease from peak/baseline value – antibiotics encouraged

Clinical Utility

Procalcitonin (PCT) has been shown to help decrease inappropriate antibiotic use and thereby decrease the rate of rise of antibiotic resistance.  It should only be ordered in patients if it will change antibiotic management.  It has been studied in a number of disease states, but the best evidence for use is as an aid in deciding whether to start antibiotics in patients with potential lower respiratory tract disease, as well as an aid in deciding to stop antibiotics in patients with suspected/confirmed sepsis. 

  • It should not be used in isolation, i.e. without incorporating other clinical & lab data
  • Cannot be used in localized infections, e.g. cellulitis, meningitis
  • Cannot distinguish between infection and colonization, e.g. asymptomatic bacteriuria vs. UTI
  • Should not be used to alter accepted management of documented infections, e.g. pyelonephritis, Staphylococcus aureus bacteremia, etc.
  • NOTE:  Use of PCT will be audited by the Antimicrobial Stewardship Team and feedback to providers on appropriateness will be performed on an ongoing basis.

PCT is a precursor of calcitonin and is thought to increase during bacterial infections as a result of bacterial blockade of calcitonin synthesis.   In patients with bacterial infections it rises rapidly (detectable within 2-4 hours and peaks within 6-24 hours) and declines with control of infection.  Unlike many other inflammatory biomarkers (e.g. C-reactive protein, ESR) PCT is not elevated in most non-infectious processes or non-bacterial infections.  It is undetectable in healthy patients.

CPT Codes



Last Updated


Microtainer® and Vacutainer® are registered trademarks of Becton, Dickinson and Company.
UroVysion® is a registered trademark of Abbott Laboratories. ThinPrep® is a registered trademark of Hologic, Incorporated.


This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.