Abstract Background Septic arthritis (SA) is a rapidly progressive joint disease that can lead to cartilage damage if not treated promptly. A prompt and accurate distinction between SA and inflammatory arthritis (IA) is essential for establishing an optimal treatment plan. Progranulin (PRGN), an anti-inflammatory glycoprotein involved in various autoimmune diseases, has rarely been studied as a diagnostic biomarker for infectious arthritis. However, its precise role in this context remains unclear. This study aimed to evaluate the diagnostic utility of synovial fluid PRGN (SF-PRGN) in distinguishing SA from IA and osteoarthritis (OA). Methods This single-center, cross-sectional study included 59 patients who underwent synovial fluid aspiration and were categorized into three groups: SA ( n = 23), IA ( n = 18), and OA ( n = 18). SA was diagnosed based on a positive synovial fluid culture or fulfillment of clinical criteria suggestive of infection. SF-PRGN levels were measured using ELISA, and synovial fluid C-reactive protein (SF-CRP) levels were determined using an immunoturbidimetric assay. Results Mean SF-PRGN levels were higher in the SA (339.77 ± 142.16 ng/mL) and IA (300.52 ± 159.60 ng/mL) groups than in the OA group (133.44 ± 41.77 ng/mL), indicating a statistically significant difference between the inflammatory and non-inflammatory groups ( p < 0.05). However, the SF-PRGN did not significantly differentiate between SA and IA ( p = 0.803). In contrast, SF-CRP levels were markedly elevated in SA (61.91 ± 46.84 mg/L) and demonstrated strong discriminatory power between SA and IA ( p < 0.001; AUC: 0.795, p < 0.0001). Conclusion Although SF-PRGN levels are elevated in inflammatory arthritis, they lack specificity for SA. SF-CRP exhibited superior diagnostic accuracy in differentiating SA from IA. These findings underscore the need for further research on reliable biomarkers of SA in larger patient cohorts. Clinical trial registration Clinical trial number not applicable.
Savaş et al. (Sat,) studied this question.