The Relationship Between Fibroblast Growth Factor 23 And Mineral Metabolism And Left Ventricular Hypertrophy In Peritoneal Dialysis Patients

Objective:Abnormal calcium-phosphate metabolism and myocardial hypertrophy are the common complications of the dialysis patients. Long-term abnormal calcium-phosphate metabolism can not only contribute to mineral metabolic abnormalities, which would result in myocardia and vascular calcification, but also relate to increased mortality of chronic renal facilure. Fibroblast growth factor 23 (FGF-23) is a recently discoved cytokine that can regulate the level of phosphorus and vitamin D, and it is largely produced by bone. Fibroblast growth factor 23 inhibits the reabsorption of inorganic phosphorus (Pi) in the proximal tubules and blocks the 1α-vitamin D3 hydroxylase. Abnormal calcium-phosphate metabolism, especially the hyperparathyroidism, would result in myocardial hypertrophy in patients with end-stage renal disease (ESRD). However, it was still unknown that if FGG-23 would relate to myocardial hypertrophy when playing a role in mechanism of calcium-phosphate metabolism in patients with ESRD. The aim of this reseach is to explore the relationship between fibroblast growth factor 23 and calcium (Ca)-phosphorus (P) metabolism, and its effect in bone mineral density (BMD) and left ventricular hypertrophy (LVH) in continuous ambulatory peritoneal dialysis (CAPD) patients. We wish the result of this study can provide evidence for prediction and prevention in renal osteodystrophy and cardiovascular disease.Methods:Seventy-eight patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and 30 healthy people were collected. Levels of FGF23, interleukin-6 (IL-6) and 1,25-(OH)2VitD3 were measured by ELISA.Parathyroid horomone(PTH) was detected by immunoradiometric assay. Calcium (Ca), phosphorus (Pi), albumin (Alb), cholesterol (Chol), hemoglobin (Hb), triacyglycerols (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL) were assessed by autobiochemistry machine. Bone densitometry (BMD) was measured by dual-energy x-ray absorptiometry (DEXA). Echocardiograpic pammeters including left arterial diameter (LAD), interventricular septal thickness (IVS), left ventricle posterior wall thickness (LVPW) and Left ventricle ejection fraction (LVEF) were recorded. Left ventricular mass index (LVMI) was calculated according to the formula described previously. Patients were considered to suffering from LVH if the LVMI was larger than 135 g/m2 in men and larger than 110 g/m2 in women.Results:(1) Compared to healthy controls, serum levels of FGF-23, IL-6, PTH, Pi, systolic pressure and diastolic pressure increased signicantly and serum levels of 1,25-(OH)2VitD3, glomerular filtration rate (GFR), Ca, Alb, Hb, BMD and T scores in femoral neck and lumbar spine decreased signicantly in CAPD patients (P <0.01). Compared to CAPD patients without LVH, Significant higher levels in FGF-23, IL-6 and systolic pressure were observed in CAPD Patients with LVH (P<0.05)(2) The CAPD patients showed an increase in LAD, higher LVMI and decreased LVEF values, comparing with the heathy controls (P< 0.05)Compared to CAPD patiente without LVH, The CAPD patients with LVH were with high level of LAD, LVDd, LVPWT, IVST and LVMI (P<0.05)(3) The incidence rate of osteoporosis in femoral neck and lumbar spine was 23.7% and 35.6% respectively. There were no significant differences of the levels of serum FGF23 among the normal group, osteopenic group, and osteoporotic group in CAPD Patients (P> 0.05) (4) Significant positive correlations were found between FGF-23 and serum phosphate (r=0.624, P<0.01), LVMI (r= 0.345, P< 0.05) and IL-6 (r=0.294, P< 0.05). We also found a significant negative correlation between FGF-23 and 1,25-(OH)2VitD3 (r=-0.451, P<0.01) and GFR (r=-0.557, P< 0.01). Meanwhile, Significant positive correlations were found between IL-6 and LVMI (r=0.445, P< 0.01) and FGF-23. However, There were no correlations between FGF-23 and BMD or T scores in CAPD patients.Conclusion:(1) Level of serum FGF-23 increased in CAPD patients, serum phosphorus and 1,25-(OH)2VitD3 would be the important adjusting factors in the level of serum FGF23.(2) There were no correlations between FGF23 and BMD. It implied that high level of serum FGF23 may not play any direct effects in bone mineralization.(3) The level of serum FGF-23 and IL-6 were related to the occurring of LVH. That implied FGF-23 and IL-6 may be the main risk factors of LVH. The combination of these two markers might improve the accidence of LVH in CAPD patients.