Is procalcitonin (PCT) a suitable marker for monitoring, diagnosing, or predicting outcomes for sepsis? Five experts offered varying insights in a Clinical Chemistry Q&A article, “The Role of Procalcitonin in Diagnosis of Sepsis and Antibiotic Stewardship: Opportunities and Challenges.”

PCT has gained evidential support as a biomarker for diagnosing bacterial sepsis and guiding discontinuation of antibiotic therapy. “Yet, there are concerns about the efficacy, safety, and availability of PCT,” the article stated.

Moderators Angela W.S. Fung, Daniel Beriault, and Eleftherios P. Diamandis queried Carey-Ann D. Burnham, Todd Dorman, Mark Downing, Joshua Hayden, and Bradley J. Langford on PCT’s strengths and limitations as a biomarker for sepsis. They also discussed its role in antibiotic stewardship, how this analyte compares with other sepsis biomarkers, and how labs should approach PCT use to diagnose sepsis.

Sepsis—a life-threatening organ dysfunction that causes death in up to 50% of all cases—is difficult to define and identify, the experts indicated. Correct, early diagnosis is critical so that patients receive needed antibiotics and other therapies to improve outcomes, Downing emphasized.

“Unfortunately, the gold standard for making a diagnosis in sepsis is isolating the organism in the microbiology laboratory, which usually takes several days or does not occur at all due to the limitations of current culture techniques,” he said.

Panelists had mixed opinions on PCT’s effectiveness as a marker for sepsis.

A key advantage is its relatively rapid rise in consonance with sepsis symptoms , Burnham offered. “Plasma PCT rises within about 3–6 hours of the initial clinical manifestations of sepsis and falls when severe infection resolves. In the setting of the emergency department, PCT may have value as an early predictor of systemic infection,” she said.

Dorman wasn’t as convinced of the clinical utility of sepsis testing. “Over time, the studies have shown that PCT is not a good diagnostic tool. Hope remains that it can be used to de-escalate therapy, with the strongest data seen in the bacterial pneumonia population,” he said.

Some evidence supports PCT’s use in guiding antibiotic therapy in respiratory tract infections. “This practice does not seem to be beneficial in critically ill patients with suspected infection,” Langford offered. Early discontinuation of antimicrobial therapy is an area where PCT might prove useful in managing sepsis, he continued.

Cost and accessibility issues have limited use of PCT testing by clinicians in the United States, Hayden said. He also wasn’t as convinced of how rapidly PCT test results become available to assist in clinical decision-making.

“Even when PCT is available, it is rarely offered 24 hours/day, 7 days/week with a turnaround time that allows it to factor into clinical decisionmaking. A marker that can help you decide the necessity of antibiotics is not terribly helpful if you get results back 6 hours after you already did or did not start treatment,” observed Hayden.

Despite its price tag, Hayden said PCT offers more value for treating sepsis patients than other markers. It’s more specific than C-reactive protein and trumps lactate as an early indicator of disease. “Seeing fire is a good way to know your house is burning down, but seeing smoke gives you more time to run,” he said in comparing PCT with lactate.

Labs planning to incorporate PCT into their antimicrobial stewardship programs need to collaborate with emergency and critical care and infectious disease experts to develop criteria for measuring PCT and using PCT results. “Education on the limitations of PCT as a marker for sepsis must be a component of the rollout of the assay,” Burnham advised.

Additionally, “there should be discussions about which patients are eligible to have PCT testing (e.g., ICU, emergency department) and recommendations on how PCT should not be used,” such as in facilitating antibiotic escalation in sepsis, Langford said.

Pick up September’s Clinical Chemistry to learn more about the advantages and limitations of PCT in sepsis management and its role in antibiotic stewardship.