Fibroblast growth factor 23 (FGF23) levels, phosphate Intake and its association with Indices of renal handling of phosphate in healthy volunteers

FGF23 is a novel phosphaturic hormone; we aimed to assess the FGF23 levels and its association with dietary phosphate intake and indices of renal handling of phosphate in this study. Prospective study was conducted in which dietary phosphate intake was assessed by food frequency questionnaire (FFQ) along with blood and spot urine samples were collected after overnight fast for determining serum phosphate, FGF23, fractional excretion of phosphate (FePO4 ) and tubular maximum for phosphate (TmP/GFR). FGF23 (C-Term) was measured by a sandwich ELISA. The mean dietary phosphate intake of eighty healthy adults (mean age of 29 ± 5 years) was 1220 ± 426 mg; median FGF23 was 49.9 RU/ml (IQR=33, 76) and mean FePO4 was 7 ± 4.7. Subjects were stratified into two groups according to serum phosphate levels. Significant difference was not found in dietary phosphate intake and FGF23 levels in the two groups. However, TmP/GFR and creatinine were significantly different in the two groups. FePO4 was high in both the groups. Overall a rising pattern of FGF23 levels was seen with increasing serum phosphate levels. Significant positive correlation was found between FGF23 and dietary phosphate (r=0.22, p\u3c0.05) and negative correlation was seen between FGF23 and FePO4 (r=-0.260, p\u3c0.05)