The serum phosphate, serum iPTH, serum FGF-23, and FEP levels significantly increased (P < 0.001) with advanced CKD stages; the median serum phosphate level (mg/dl) was 4.60, 4.90, 5.10, and 5.80 in CKD stages 3a, 3b, 4, and 5, respectively, and the levels of iPTH, FGF-23, and FEP constantly increased as the CKD stage advanced from stage 1 to 5 (P < 0.001). The gene discussed is FGF23; the disease is chronic kidney disease.