TOPLINE:

Children with systemic juvenile idiopathic arthritis (sJIA; Still disease) and those with rheumatoid factor (RF)-positive polyarthritis exhibiting high disease activity had higher serum ferritin levels than those with other JIA subtypes, underscoring serum ferritin's potential as a marker of disease activity across all JIA subtypes.

METHODOLOGY:

• Researchers conducted a retrospective study to evaluate the role of serum ferritin as a marker of disease activity within the full spectrum of JIA subtypes in children.
• They evaluated 139 children with JIA and categorised them as those with persistent oligoarthritis, extended oligoarthritis, RF-negative polyarthritis, RF-positive polyarthritis, enthesitis-related arthritis, psoriatic arthritis, or sJIA.
• Disease activity was assessed using the Juvenile Arthritis Disease Activity Score 10 (JADAS-10), with scores classifying the disease state as inactive disease, low disease activity, moderate disease activity, or high disease activity.

TAKEAWAY:

• Children with sJIA and RF-positive polyarthritis had significantly higher serum ferritin levels than those with other JIA subtypes (P < .0001 for both).
• The highest serum ferritin levels were observed in children with sJIA and RF-positive polyarthritis with high disease activity (P = .003).
• A positive association was observed between serum ferritin levels and JADAS-10 scores, independent of BMI and age (P < .0001), which remained significant in patients with sJIA (P < .0001) and RF-positive polyarthritis (P = .008).

IN PRACTICE:

"Serum ferritin might serve as a clinically and prognostically useful biomarker across the full spectrum of JIA subtypes, with particular relevance in sJIA and RF-positive polyarthritis," the authors wrote.

SOURCE:

This study was led by Maria Francesca Gicchino, Department of Woman, Child, and General and Specialized Surgery, University of Campania "Luigi Vanvitelli," Naples, Italy. It was published online on August 27, 2025, in the European Journal of Pediatrics.

LIMITATIONS:

This study was limited by its retrospective and single-centre nature, the lack of anti-cyclic citrullinated peptide antibody measurements, and the lack of longitudinal data. Moreover, the lack of early follow-up data in all patients restricted the assessment of ferritin dynamics and treatment response over time.

DISCLOSURES:

This study did not disclose any specific funding. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.