Procalcitonin Ordering and Reporting Practices Among Clinical Laboratories: Findings From a College of American Pathologists Proficiency Testing Survey

Context.— Procalcitonin is a biomarker that aids in distinguishing bacterial infections from other types of inflammation. The diagnostic accuracy of procalcitonin varies and clinical utility recommendations are mixed. Procalcitonin test utilization and resulting practices vary among laboratories. Objective.— To characterize practices related to procalcitonin testing. Design.— A supplemental questionnaire was distributed with the College of American Pathologists Procalcitonin 2025 Survey. Results.— There were 2009 respondents. Of 2001 respondents, 1885 (94.2%) were hospital-based laboratories, primarily from 1028 institutions with fewer than 250 beds (51.4%). Annual procalcitonin testing volumes varied; 483 of 1945 (24.8%) performed fewer than 499 procalcitonin tests per year, 526 (27.0%) performed 500 to 1999 tests per year, and 210 (10.8%) performed at least 10 000 tests per year. Most laboratories (1329 of 1977; 67.2%) defined their procalcitonin reference range by verifying the manufacturer’s range. Two hundred sixty-eight (13.6%) reported using a clinical cutoff and 112 (5.7%) established an institution-specific range. Three hundred forty of 1958 respondents (17.4%) reported having a critical value, and thresholds differed (median, 2.0 ng/mL among 327 respondents). Stewardship involvement in procalcitonin interpretation was reported by 608 of 1956 respondents (31.1%), while 917 (46.9%) were unsure. Nearly half of the laboratories (865 of 1960; 44.1%) were unsure of institutional guidance for procalcitonin ordering, and 1115 of 1963 (56.8%) reported no ordering restrictions. Conclusions.— Variability exists among laboratories regarding ordering and resulting practices for procalcitonin, with nonstandardized institutional guidance and limited stewardship involvement at most hospitals. These findings highlight the opportunity for laboratories and clinicians to collaborate and optimize procalcitonin utilization.