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.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
80
Single study visit during routine nephrology follow-up. Routine blood analyses are performed as standard care. Two additional tubes (maximum 10 mL) are collected: * EDTA plasma tube for measurements of intact FGF23 (iFGF23), C-terminal FGF23 (cFGF23), and hepcidin. * Serum tube for measurements of erythropoietin (EPO), 1,25-dihydroxyvitamin D, and TRAP5b. Clinical and laboratory data collected include renal function parameters (eGFR, creatinine, urea, albuminuria), hematologic and iron metabolism markers (hemoglobin, ferritin, transferrin saturation, CRP), and bone-mineral metabolism markers (calcium, phosphate, PTH, vitamin D, bone alkaline phosphatase).
CHU de Saint-Etienne
Saint-Etienne, France
Evaluate the association between CKD stages and the intensity of circulating FGF23 cleavage in CKD patients.
The intensity of FGF23 cleavage will be estimated using the iFGF23/cFGF23 ratio and compared across CKD stages 3a to 5.
Time frame: At inclusion
Plasma concentrations of iFGF23 and cFGF23
Evaluation of changes in circulating intact FGF23 and C-terminal FGF23 concentrations according to CKD stage.
Time frame: At inclusion
Association between FGF23 cleavage intensity and anemia-related parameters
Assessment of associations between iFGF23/cFGF23 ratio and hemoglobin, ferritin, transferrin saturation, CRP, hepcidin and erythropoietin independently of CKD stage.
Time frame: At inclusion
Association between FGF23 concentrations and renal parameters
Assessment of associations between iFGF23 and cFGF23 concentrations and eGFR, creatinine and albuminuria using correlation and multivariable analyses.
Time frame: At inclusion
Association between FGF23 concentrations and mineral-bone metabolism markers
Assessment of associations between iFGF23 and cFGF23 concentrations and phosphate, calcium, PTH, vitamin D, bone alkaline phosphatase and TRAP5b.
Time frame: At inclusion
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