Fibroblast Growth Factor (FGF-23) in Pre-Dialytic Chronic Kidney Disease Patients

Objective: Fibroblast Growth Factor (FGF-23); a Phosphaturic peptide hormone, has recently been identified as a regulator of calcium-Phosphorus metabolism. Aim of the present study was to analyse FGF-23 in addition to the conventional indicators of bone metabolism in pre-dialytic CKD patients. METHODS: Pre-dialytic CKD Stage 1 & 2 (N=10) and Stage 3 & 4 (N=14) patients were observed for different indicators of bone metabolism including Total, intact (active) and C-terminal FGF-23 (inactive) levels at recruitment as compared to age matched controls (N=14) and as compared to their profile at six month. RESULTS: In CKD stage (1-4) patients, phosphorus levels were within normal range but showed negative correlation with eGFR (Linear correlation (r) = -0.467, p=0.021) and positive correlation with C-terminal FGF-23 levels (spearman correlation (rs) = 0.464, p=0.022). As compared to the controls, in stage 1 and 2 Total, intact and C-terminal FGF-23 increased significantly (p=0.001) by 16.4, 2.1 and 19.2 fold and in stage 3 and 4 by 28.6, 2.4 and 32.3 fold respectively. Thus, increase in the C-terminal by intact-FGF-23 in control, CKD stage 1 & 2 and CKD stage 3 & 4 were 4.5, 41.8 and 60.6 fold respectively. These patients were on regular calcium and vitamin D treatment. Follow-up study at six month did not show any change in FGF-23 levels. CONCLUSION: In the absence of hyperphosphatemia at early stages of CKD, FGF-23 levels increased with declining renal function. Increase in C-terminal FGF-23 over intact-FGF23 levels might greatly advance understanding of mineral bone disease in CKD