Correlation between serum hepcidin and calcium-phosphorus metabolism indices in continuous ambulatory peritoneal dialysis patients

Abstract

Objective To investigate the changes of serum hepcidin levels and the relationship between calcium and phosphorus metabolism and hepcidin levels in patients with continuous ambulatory peritoneal dialysis (CAPD). Methods Forty-five patients who underwent CAPD treatment at the Blood Purification Center of Jiangsu Subei People's Hospital from June to December 2014 were selected. Forty healthy people who underwent health check-up at the hospital were used as healthy controls. Serum hepcidin levels were detected by ELISA. The two sample t-test was used to compare age, body mass index (BMI), blood urea nitrogen (BUN), creatinine, albumin, phosphorus, calcium, 25(OH)-vitamin D3, serum iron, total iron binding capacity (TIBC), soluble transferrin receptor (sTfR), hemoglobin, and hematocrit between the CAPD group and the control group. The Mann-Whitney rank test was used to compare whole-stage parathyroid hormone (iPTH) and ferritin as well as hepcidin levels. The χ2 test was used to compare the gender distribution of the two groups. Pearson correlation and multiple stepwise linear regression were used to analyze the correlation between hepcidin and calcium and phosphorus metabolic indicators. Results Compared with the control group, serum levels of hemoglobin, hematocrit, albumin, iron, TIBC, transferrin saturation, and 25(OH)-vitamin D3 were significantly lower in the CAPD group [(89.62±20.04) g/L vs (121.53±4.06) g/L, t=-8.72, P<0.001; (26.81±5.68)% vs (40.82±2.04)%, t=-9.64, P<0.001; (43.25±1.23) g/L vs (45.26±1.29) g/L, t=-1.27, P=0.046; (10.27±2.36) μmol/L vs (18.52±4.41) μmol/L, t=-5.71, P<0.001; (65.40±2.89) μmol/L vs (75.84±5.03) μmol/L, t=-2.34, P=0.037; (15.34±5.44)% vs (29.65±4.77)%, t=9.31, P<0.001; (39.57±7.23) nmol/L vs (79.12±10.38) nmol/L, t=-10.34, P<0.001]. Compared with the control group, the levels of BUN, creatinine, ferritin, sTfR, hepcidin, iPTH, and phosphorus in the CAPD group were significantly higher [(18.87±7.64) mmol/L vs (4.26±1.18) mmol/L, t=8.27, P<0.001; (647.43±56.78) μmol/L vs (54.81±6.74) μmol/L, t=8.26, P<0.001; 260.41 (109.31, 423.33) μg/L vs 109.33 (60.54, 159.62) μg/L, Z=-4.24, P=0.001; (4.27±1.45) mg/L vs (2.89±1.22) mg/L, t=1.79, P=0.048; 234.24 (134.22, 437.19) μg/L vs 87.51 (40.54, 132.57) μg/ L, Z=-5.27, P<0.001; 26.10 (15.04, 50.35) ng/L vs 3.30 (1.78, 6.25) ng/ L, Z=-5.61, P<0.001; (2.73±0.47) mmol/L vs (1.24±0.65) mmol/L, t=12.09, P<0.001]. Pearson correlation analysis showed that serum hepcidin was positively correlated with serum phosphorus (r=0.300, P=0.003) and iPTH (r=0.313, P=0.02) levels in patients with CAPD, but was not associated with serum calcium (r=-0.064,P=0.531) or 25(OH)-vitamin D3 levels (r=0.007, P=0.943). Conclusion Serum hepcidin levels are significantly elevated in patients with CAPD, and are positively correlated with serum phosphorus and iPTH levels. Serum phosphorus and iPTH may be involved in the regulation of hepcidin. Key words: Continuous ambulatory peritoneal dialysis; Hepcidin; Calcium and phosphorus metabolism