Immature Granulocyte: A Novel Inflammatory Biomarker in Familial Mediterranean Fever

Our study aimed to evaluate the significance and clinical utility of immature granulocyte (IG) count (IGC) and IG percentage (IG%) in predicting attacks in patients with familial Mediterranean fever (FMF).

This retrospective study included 100 FMF patients and 50 healthy controls. Data from 24 patients during the attack period and 76 patients during the attack-free period in the FMF group were obtained from medical records. Complete blood count analyses were carried out with the Mindray BC-6200 automated hematology analyzer following standard laboratory protocols. Receiver operating characteristic (ROC) curve analysis was conducted to differentiate FMF patients in the attack period from those in the attack-free period.

In FMF patients, levels of WBC (p = 0.032), neutrophils (p = 0.001), C-reactive protein (CRP) (p = 0.002), IG count (p < 0.001), and IG percentage (p < 0.001) were significantly higher compared to healthy controls. During the attack period, IG count and IG percentage levels were significantly elevated compared to the attack-free period (p < 0.001 for both). Based on ROC analysis, IG count and IG percentage showed significant diagnostic potential in FMF patients, with AUC values of 0.841 and 0.766, respectively.

IGC and IG% serve as indicators of inflammation in FMF patients and may facilitate the differential diagnosis of FMF attacks, with respective cut-off values of 0.04 × 10⁹/L and 0.4%. Given their accessibility and lack of additional cost, these parameters have the potential to enhance clinical practice by augmenting the diagnostic utility of conventional inflammatory biomarkers.