The prognostic and diagnostic value of fibroblast growth factor 23 in patients undergoing hemodialysis

Abstract

Fibroblast growth factor 23 (FGF23) is a phosphotropic hormone secreted by osteoblasts and osteocytes into the systemic circulation. It exerts its effects on the kidneys, parathyroid glands, heart, and bones. FGF23 is a critical phosphaturic hormone that, alongside parathyroid hormone (PTH), regulates phosphate reabsorption and calcitriol (1,25(OH)₂D) synthesis in the kidneys. The present study aimed to evaluate the diagnostic and prognostic significance of fibroblast growth factor 23 in patients undergoing hemodialysis.

Methods. A total of 88 patients were examined in this cross-sectional study. The cohort comprised 36 women (40.9%; 95% CI 30.64–51.18) and 52 men (59.1%; 95% CI 48.82–69.36), with a mean age of 55.81 ± 13.14 years. Group 1 consisted of 69 patients with stage 5 chronic kidney disease (CKD) receiving renal replacement therapy via hemodialysis, while Group 2 included 19 patients with stage 3 CKD.

Results. FGF23 levels were elevated in 67 patients (97.1%; 95% CI 91.87–99.72) in Group 1, with a median (Me) of 1258.32 pg/mL (interquartile range [IQR] 169.46–1338.46). In Group 2, FGF23 levels were elevated in 18 patients (94.7%; 95% CI 80.58–100), with a median of 150.5 pg/mL (IQR 74.22–929.12). A significant difference was observed between the groups (p < 0.05). The median duration of hemodialysis in Group 1 was 15 months (IQR 8–36). In Group 1, correlation analysis revealed weak associations between FGF23 and phosphorus (r = 0.13; p > 0.05), total calcium (r = 0.04; p < 0.05), ionized calcium (r = 0.02; p < 0.05), and parathyroid hormone (r = 0.08; p > 0.05). Significant correlations were found between FGF23 and creatinine (r = 0.41; p < 0.005), urea (r = 0.33; p < 0.005), urine volume (r = -0.75; p < 0.005), and hemodialysis duration (r = 0.57; p < 0.005). Regression analysis for predicting residual urine volume based on FGF23, creatinine, urea, and hemodialysis duration yielded an R² of 0.7369, F-statistic of 92.45 (p < 0.0001), standard error of residuals of 5.843, and residual degrees of freedom of 66.

Conclusions. The weak correlations between FGF23 and calcium-phosphorus metabolism indicate that FGF23 is not a suitable diagnostic marker for mineral and bone disorders (CKD-MBD) in patients undergoing hemodialysis. However, FGF23 is a significant predictor of residual urine volume in hemodialysis patients, as demonstrated by the regression analysis. The model, incorporating FGF23 and hemodialysis duration, explains 73.7% of the variation in urine volume, highlighting its strong prognostic capability. These findings underscore the clinical significance of FGF23 as a biomarker for assessing residual renal function in dialysis patients.