Association Between Chronic Kidney Disease Stage and Circulating FGF23 Cleavage Intensity in Patients With Chronic Kidney Disease

This cross-sectional proof-of-concept study aims to investigate the relationship between chronic kidney disease (CKD) severity and circulating FGF23 (fibroblast growth factor 23) cleavage intensity estimated by the iFGF23/cFGF23 ratio. Eighty male patients aged 55-75 years with CKD stages 3a to 5 will be included (20 per stage). Blood samples obtained during routine nephrology care will be supplemented by two additional tubes to measure iFGF23, cFGF23, hepcidin, erythropoietin, 1,25-vitamin D and TRAP5b. The primary endpoint is the iFGF23/cFGF23 ratio. Secondary analyses will evaluate the associations between FGF23 forms and renal, hematological, iron metabolism and mineral bone parameters. This study will provide the first human data on FGF23 cleavage alterations across CKD stages and may identify novel biomarkers for anemia and cardiovascular complications.

Inclusion Criteria: * MRC stage 3a-5 based on the most recent GFR measurement * Patient enrolled in or eligible for a social security program * Patients who have received informed consent regarding the study and have given their verbal consent to participate Exclusion Criteria: * Active cancer or a history of cancer in remission for less than 5 years, or a history of cancer in remission for more than 5 years with specific oncological treatment still ongoing. * Participation in another study related to treatments for the disease * Patients under legal guardianship (legal guardianship or conservatorship)