#4-55E. Rethinking Procalcitonin: Predicting MAS in Still's Disease (Rheumatology, 2026)

Do you always equate a sudden spike in procalcitonin with a bacterial infection? In the context of autoinflammatory conditions like Still's disease, this assumption might delay critical interventions1. This episode dives into a recent retrospective study exploring the clinical significance of non-infectious procalcitonin, or PCT, elevation in 110 patients with Still’s disease. Researchers discovered that elevated PCT levels, specifically a baseline or peak of 0.5 ng/ml or higher, serve as a strong independent predictor for the development of macrophage activation syndrome (MAS), a life-threatening complication, even in the complete absence of infection. However, when critically appraising this evidence, clinicians must consider the study's retrospective design and relatively small subgroup sample sizes, which limit the generalizability of the findings and underscore the need for prospective longitudinal data. For the practicing physician, these insights are highly relevant; they challenge the conventional infectious paradigm of PCT and demonstrate its dual utility. Monitoring PCT in Still's disease can guide early risk assessment for MAS, prompting timely, intensified immunosuppressive therapy rather than merely empirical antibiotics, ultimately improving outcomes in rheumatologic care.

Citation: Erdem Bektas, et al. Clinical significance of non-infectious procalcitonin elevation in Still’s disease: a predictor of macrophage activation syndrome. Rheumatology. 2026. DOI: 10.1093/rheumatology/keaf575

Disclaimer: This audio summary is based on personal interpretation and does not guarantee the exact content of the original paper. Please refer to the original article for details.