Preliminary Evaluation Of The Effect Of Parathyroid Hormone On FGF23 And Its Clinical Significance In Maintenance Hemodialysis Patients

ObjectivesDisorders of mineral and bone metabolism are common complications of chronic kidney disease (CKD), and they are investigated mainly in association with secondary hyperparathyroidism (SHPT). Long-term phosphate retention, hypocalcemia and a progressive decline in 1,25-dihydroxyvitamin D [1,25(OH)2D3] will increase SHPT and lead to renal osteodystrophy (ROD). The limitations of diagnosis lead to the high incidence and poor prognosis of ROD. Fibroblast growth factor 23 (FGF23) was identified initially as a phosphatonin. Elevated FGF23 levels result in decreased renal production of 1,25(OH)2D3, possibly thereby worsening SHPT. The exact clinical significance of FGF23 is still not clear. Current studies suggest that phosphorus and 1,25(OH)2D3 are the two important factors in the regulation of FGF23, while the relationship between FGF23 and PTH is still not sure. This study is designed to clarify the correlation among circulating FGF23, iPTH, mineral and bone metabolism, and also to explore circulating FGF23 level and bone metabolism long-term and short-term changes after total parathyroidectomy with forearm autotransplantation, to preliminary evaluate the effect of PTH on FGF23 and its clinical significance in maintenance hemodialysis (MHD) Patients.MethodsThis study is divided into three parts.Part 1:Thirty patients with MHD were grouped according to PTH levels into high-PTH group (H-PTH group, PTH>500pg/mL), normal-PTH group (N-PTH group, 1500.05). The level of plasma iFGF23 by Pearson relativity analysis was significantly correlated positively with serum phosphorus (r=0.80, p<0.01), iPTH (r=0.71, p<0.01) and BAP (r=0.77, p<0.01). No relationship was found between FGF23 and 1,25(OH)2D3, serum calcium, ICTP. Serum phosphorus and BAP were found to be two variables independently that influenced the level of plasma iFGF23 by multiple regression model.Part 2:The levels of serum calcium and phosphorus in PTX group were lower than that in non-PTX group by paired comparison (p<0.05). Plasma iFGF23, BAP and ICTP in PTX group were also significantly lower than that in none-PTX group (p<0.05). The level of 1,25(OH)2D3 was slightly higher in PTX group. But there was no significant differences found between two groups (p>0.05). The level of plasma iFGF23 by Pearson relativity analysis was significantly correlated positively with serum phosphorus (n=0.68, p<0.05) in PTX group. No relationship was found between FGF23 and iPTH,1,25(OH)2D3, serum calcium, BAP, ICTP.Part 3:The iPTH, serum calcium and phosphorus decreased significantly in the 1st and 7th day after PTX (p<0.01). And also the operation ameliorated the plasma iFGF23, serum BAP and ICTP in the 1st,3rd and 7th day after PTX (p<0.05).1,25(OH)2D3 elevated in the 3rd and 7th day after PTX (p<0.05). But no significant difference was found in the 1st day after PTX (p>0.05).ConclusionsFGF23 is regulated by many factors in maintenance hemodialysis patients, especially serum phosphorus. Plasma FGF23 levels significantly decreased after PTX, suggesting that FGF23 may be regulated by PTH in indirect or/and direct way. FGF23 is significantly associated with bone resorption and formation markers in maintenance hemodialysis patients. It may be used as one of important markers on clinical diagnosis and assessment of bone metabolism.