Procalcitonin has been described as being useful in assisting physicians in the diagnosis of acute infection in several different conditions. Some of these are:
Immediately following collection, mix sample thoroughly by gently inverting 8 - 10 times to prevent clotting
Spin within two (2) hours of sample collection
Plasma separator (Lt green PST)
Immediately following collection, thoroughly mix sample by gently inverting 5 times
Gold serum separator (SST) tube
48 hrs when removed from the clot or gel
8 hours on the clot or gel
24 hours when removed from the clot or gel
Chemiluminescent microparticle immunoassay (CMIA)
< 0.50 ng/mL
PCN is the prohormone of calcitonin (CT). Whereas CT is secreted by the C-cells of the thyroid after hormonal stimulation, PCN can be produced by numerous cell types and organs after proinflammatory stimulation, especially when caused by a bacterial triggering event.
One major advantage of PCN compared to other inflammatory parameters is its early and highly specific increase in response to severe systemic bacterial infections and sepsis. PCN levels closely parallel the severity of the inflammatory insult, with higher levels associated with more severe disease and declining levels with resolution of illness. In septic conditions, increased PCN levels can be observed within 3 to 6 hours after a triggering event, and peaks by 12 to 24 hours with a half-life of 24 to 35 hours, making it suitable for serial monitoring. PCN levels are usually low in viral infections, chronic inflammatory disorders or autoimmune processes. PCN levels in sepsis are generally greater than 0.5 - 2 ng/mL and often reach values between 10 and 100 ng/mL, or considerably higher in individual cases, thereby enabling diagnostic differentiation between these various clinical conditions and a severe bacterial infection (sepsis).
The dependence of sustained PCN elevations on ongoing inflammatory stimuli allows for the identification of secondary septic events in conditions that can result in noninfectious PCN elevations, such as cardiac surgery, severe trauma, severe burns, and multi-organ failure. PCN levels should fall at a predictable pace in the absence of secondary infection.
The following interpretation table is currently in use within Allina Health.
Procalcitonin for initial assessment of Lower Respiratory Tract Infection:
|< 0.1 ng/mL||Antibiotics strongly discouraged*|
|0.1 – 0.25 ng/mL||Antibiotics discouraged *|
|0.26 – 0.50 ng/mL||Antibiotics encouraged**|
|> 0.50 ng/mL||Antibiotics strongly encouraged **|
*If suspicion of infection high, clinically unstable, or immunosuppressed: initiate antibiotics. Repeat PCT testing in 6-24 hours.
**Repeat PCT testing every 1-2 days while on antibiotics to assess response to therapy.
Procalcitonin for initial assessment of severe sepsis risk:
|< 0.5 ng/mL||Associated with a low risk for progression to severe sepsis/septic shock|
|> 2.0 ng/mL||Associated with a high risk for progression to severe sepsis/septic shock|
Note: PCT levels below 0.5 ng/mL do not exclude an infection, because localized infections may also be associated with such low levels. If the PCT measurement is done very early after the systemic infection process has started (usually <6 hours), these values may still be low.
PCT levels between 0.5 ng/mL and 2.0 ng/mL should be interpreted in the context of the specific clinical background and conditions of the individual patient. It is recommended to re-test PCT within 6-24 hours if any concentrations <2.0 ng/mL are obtained.