KIM-1: A Non-Invasive Marker for Kidney Injury and Treatment Efficacy in FMF

Objective: Familial Mediterranean Fever (FMF) arises from mutations in the MEFV gene, which encodes the immune-regulatory protein pyrin. Early detection of FMF-associated kidney injury and identification of noninvasive biomarkers to monitor disease progression and treatment response are critical. This study aimed to measure serum Kidney Injury Molecule-1 (sKIM-1) levels in FMF patients, assess its potential as an early indicator of renal damage, and evaluate its utility in monitoring treatment efficacy. Methods: Fifty FMF patients and 36 healthy controls were enrolled. Serum KIM-1 levels were determined by ELISA. Clinical and laboratory data were extracted from patient records. The relationships between sKIM-1, urine protein/creatinine ratio (UPCR), and estimated glomerular filtration rate (eGFR) were analyzed. Subgroup analyses compared sKIM-1 levels in patients treated with anakinra or canakinumab. Results: Median sKIM-1 was significantly higher in FMF patients than controls [571.30 pg/mL (562.50–586.90) vs. 562.40 pg/mL (558.10–580.40), p=0.040]. No correlation was observed between sKIM-1 and UPCR (p=0.547) or eGFR (p=0.232) in the FMF group. Canakinumab-treated patients exhibited significantly lower sKIM-1 levels [561.10 pg/mL (556.10–567.00) vs. 575.4 pg/mL (564.00–591.20), p=0.036], whereas anakinra treatment showed no significant difference [561.20 (558.40-595.70), 572 (564.60-588), (p=0.430)]. Conclusion: Elevated sKIM-1 in FMF patients and its reduction with canakinumab support KIM-1 as a noninvasive biomarker of renal involvement in FMF. These findings suggest KIM-1 may serve as a tool for monitoring disease activity and treatment response.