Understanding Procalcitonin

Utilizing the right test for optimal patient outcomes

When a patient presents with signs of infection, a timely diagnosis is essential. This is especially true for patients with severe infections such as LRTI, secondary bacterial infection associated with COVID-19, or sepsis.

It is common to encounter patients who present symptoms—such as cough, shortness of breath, and fever—that can be associated with several different diagnoses (e.g. a case of chronic obstructive pulmonary disease (COPD) exacerbation). One of your first questions will likely be, “Does my patient have a bacterial infection or is there a non-bacterial cause of the current exacerbation?” Followed by, “Does the patient need antibiotics?” 

Whether in the emergency department (ED), intensive care unit (ICU) or another hospital ward, consider ordering a procalcitonin (PCT) test along with other diagnostic tests when a bacterial infection is possible. 

Baseline PCT testing, in conjunction with clinical signs and symptoms, may tell you if a bacterial infection is likely or not. Initiation of antibiotic treatment depends on the severity of the illness and the patient’s outcome risk. In high-risk patients with severe illness in the ICU, initiation of empiric antibiotic treatment is based on clinical judgment. In patients with mild illness outside the ICU in which bacterial infection is uncertain, baseline PCT can help clinicians decide whether to initiate antibiotics or consider an alternative diagnosis.² (Keep in mind: It only takes approximately 20 minutes to get results.)

Serial PCT measurements can indicate whether the patient is responding to the antibiotics or you need to consider a course change. PCT levels should be trended every 24 to 48 hours to determine when the infection has resolved enough that antibiotics can be safely stopped. Discontinuing antibiotic treatment can be considered in clinically stable patients when the PCT level has dropped below the respective cut-offs for sepsis or LRTI, or when it has decreased by ≥ 80% of the peak value

• Patients experiencing major trauma and/or recent surgical procedure including extracorporeal circulation or burns;
• Patients under treatment with OKT3 antibodies, OK-432, interleukins, TNF-alpha and other drugs stimulating the release of pro-inflammatory cytokines or resulting in anaphylaxis;
• Patients diagnosed with active medullary C-cell carcinoma, small cell lung carcinoma, or bronchial carcinoid;
• Patients with prolonged or severe cardiogenic shock, prolonged severe organ perfusion anomalies or after resuscitation from cardiac arrest;
• Patients with acute or chronic viral hepatitis, decompensated severe liver cirrhosis (Child-Pugh Class C) and/or acute liver failure;

• Patients receiving peritoneal dialysis or hemodialysis treatment;
• Patients with biliary pancreatitis, chemical pneumonitis or heat stroke;
• Patients with invasive fungal infections (e.g. candidiasis, aspergillosis ) or acute attacks of plasmodium falciparum malaria;
• Patients with Kawasaki, Still’s Disease or Bell’s Palsy;
• Patients with mushroom poisoning;
• Patients with preeclampsia;
• Patients with paracetamol intoxication;
• Also severity of renal failure or insufficiency, may influence procalcitonin values and should be considered as potentially confounding clinical factors when interpreting PCT values.