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Procalcitonin

Procalcitonin, Plasma

Test Codes

EPIC: LAB6906, PCT

Department

Chemistry

Specimen Collection Criteria

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

Do NOT use Gold-top Serum Separator (SST) tubes, Dark Green-top 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)

For Dark Green top Lithium Heparin tubes: Invert 8 times for proper mixing of heparin anticoagulant, then centrifuge immediately to separate plasma from cells and aliquot plasma into a labeled tube. Refrigerate (2-8 degrees C or 36-46 degrees F) the labeled aliquot tube.

Preparation for Courier Transport

Transport:

• Centrifuged PST tube, refrigerated (2-8°C or 36-46°F). (Minimum: 1.0 mL plasma)
• Labeled aliquot 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.
• Dark Green-top Lithium Heparin tubes not spun; plasma not in labeled aliquot tubes or not refrigerated.
• Specimens collected in inappropriate collection tubes.
• Specimens not collected and processed as indicated. 

In-Lab Processing

Centrifuge PST tubes or dark green top lithium heparin 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.

Storage

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

Laboratory

Dearborn Chemistry Laboratory
Grosse Pointe Chemistry Laboratory
Royal Oak Automated Chemistry Laboratory
Royal Oak Stat Laboratory
Troy Chemistry Laboratory
Taylor Chemistry Laboratory
Trenton Chemistry Laboratory 

Performed

Sunday – Saturday.
Results available within 24 hours. 

Reference Range

Less than or equal to 0.25 ng/mL.

Test Methodology

Chemiluminescence Immunoassay.

Interpretation

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

84145
LOINC: 75241-0

Contacts

Last Updated

4/18/2022