From the Guidelines
Elevated procalcitonin (PCT) levels are primarily caused by bacterial infections, particularly those involving gram-negative organisms 1. Certain medications, such as glucocorticoids (e.g., prednisone at doses ≥ 20 mg/day for ≥ 3 days) and some immunosuppressants (e.g., cyclosporine at doses ≥ 2 mg/kg/day), can also increase PCT levels. Additionally, major surgical procedures, severe trauma, and burns can lead to elevated PCT levels, often peaking within 24-48 hours after the initial insult 1.
Key Points
- PCT levels can rise within 2-3 hours of onset of bacterial infection, with higher levels observed in more severe infections 1
- PCT levels are associated with the severity of infection and decrease rapidly after antibiotic treatment 1
- Serial measurement of PCT can be useful in guiding antibiotic discontinuation and predicting secondary bacterial infections in critically ill patients 1
- A PCT level of <0.25 ng/mL can be used as a cut-off value for safe de-escalation or discontinuation of antibiotics in COVID-19 patients 1
Causes of Elevated PCT Levels
- Bacterial infections (particularly gram-negative organisms)
- Certain medications (glucocorticoids, immunosuppressants)
- Major surgical procedures
- Severe trauma
- Burns
- Secondary bacterial infections in COVID-19 patients 1
From the Research
Causes of Elevated Procalcitonin (PCT) Levels
Elevated procalcitonin (PCT) levels are associated with various conditions, including:
- Bacterial infections, particularly Gram-negative bloodstream infections 2, 3, 4
- Systemic inflammatory response syndrome (SIRS) of infectious origin 4
- Severe systemic parasitic or fungal infections 4
- Multidrug-resistant Gram-negative bacilli, such as A. baumannii, K. pneumoniae, and P. aeruginosa 2
- Postoperative complications, including infections, after elective colorectal surgery 3
Special Patient Populations
In special patient populations, such as those with renal dysfunction, cardiac compromise, or immunocompromised states, PCT levels may be elevated at baseline and increase further in the presence of infection 5. However, the optimal threshold for diagnosing infection or de-escalating therapy in these populations is unclear.
COVID-19 and PCT Levels
In children with COVID-19, elevated PCT levels have a low positive predictive value (PPV) for identifying bacterial infections, particularly in those with multisystem inflammatory syndrome in children (MIS-C) 6. This suggests that PCT levels should be interpreted with caution in patients with COVID-19.
Key Findings
- Elevated PCT levels are a reliable marker of bacterial infection in many cases 2, 3, 4
- PCT levels can distinguish between Gram-negative and Gram-positive bloodstream infections 2
- PCT-guided antimicrobial therapy may be recommended in certain clinical situations, but should be considered along with clinical criteria 5