Fibroblast growth factor 23 is associated with left ventricular hypertrophy, not with uremic vasculopathy in peritoneal dialysis patients.

AIMS: Cardiovascular (CV) events are the leading cause of morbidity and mortality in patients with chronic kidney disease (CKD), including those patients on peritoneal dialysis (PD). Fibroblast growth factor 23 (FGF23) has been associated with left ventricular hypertrophy (LVH) and mortality in patients with CKD. However, the role of FGF23 in uremic vasculopathy remains unclear. In this study, we aimed to assess the relationship between FGF23 and LVH, endothelial dysfunction, vascular calcification, and arterial stiffness in 48 stable PD patients. METHODS: Left ventricular mass index (LVMI) was assessed using 2-D echocardiography. Intact FGF23 blood levels were evaluated using an ELISA kit (Immutopics, Inc., San Clemente, CA, USA). Reactive hyperemia index (RHI) is a surrogate marker of endothelial dysfunction and the augmentation index (AI) is a surrogate marker of arterial stiffness. Both were assessed using peripheral arterial tonometry (EndoPAT 2000). Vascular calcification (VC) was assessed using the Adragão score. RESULTS: In unadjusted analysis; FGF23 was positively correlated with serum Pi (r = 0.487, p < 0.001), serum urea (r = 0.351, p = 0.015), serum creatinine (r = 0.535, p < 0.001), dialysis vintage (r = 0.309, p = 0.033), and LVMI (r = 0.369, p = 0.027) and was negatively correlated with age (r = -0.343, p = 0.017), residual renal function (r = -0.359, p < 0.012), and AI (r = -0.304, p = 0.038). In multivariate adjusted analysis, FGF23 was associated with LVMI (ß = 0.298, p = 0.041), serum Pi (ß = 0.345, p = 0.018), and age (ß = -0.372, p = 0.007) independent of dialysis vintage, gender, residual renal function (RRF), albumin, C-reactive protein and systolic blood pressure. There were no associations found between FGF23 and RHI, AI, or VC in multivariable- adjusted models. CONCLUSIONS: Our results show that FGF23 is associated with LVH but not with endothelial dysfunction, arterial stiffness, or vascular calcification in PD patients.

Phase Angle Predicts Arterial Stiffness and Vascular Calcification in Peritoneal Dialysis Patients.

OBJECTIVES: Fluid overload (FO) is frequently present in peritoneal dialysis (PD) patients and is associated with markers of malnutrition, inflammation, and atherosclerosis/calcification (MIAC) syndrome. We examined the relationships in stable PD patients between phase angle (PhA) and the spectrum of uremic vasculopathy including vascular calcification and arterial stiffness and between PhA and changes in serum fetuin-A levels. METHODS: Sixty-one stable adult PD patients were evaluated in a cross-sectional study (ST1). Phase angle was measured by multifrequency bioimpedance analysis (InbodyS10, Biospace, Korea) at 50 kHz. Augmentation index (AI), a surrogate marker of arterial stiffness, was assessed by digital pulse amplitude tonometry (Endo PAT, Itamar Medical, Caesarea, Israel). Vascular calcification was assessed by simplified calcification score (SCS). Serum fetuin-A levels were measured by ELISA (Thermo scientific; Waltham, MA, USA). Serum albumin was used as a nutritional marker, and serum C-reactive protein (CRP) was used as an inflammatory marker. The same assessments were carried out longitudinally (ST2) in the first 33 patients who completed 1 year of evaluation in ST1. RESULTS: In ST1, patients with PhA < 6° had higher CRP levels, AI, and SCS and lower serum albumin and fetuin-A levels, in comparison with patients with PhA ≥ 6°. In addition, PhA was a predictor of both AI (ß = -0.351, p = 0.023) and SCS ≥ 3 (EXP (B) = 0.243, p = 0.005). In ST2, the increase of PhA over time was associated with decreases in both AI (r = -0.378, p = 0.042) and CRP levels (r = -0.426, p = 0.021), as well as with the increase in serum fetuin-A levels (r = 0.411, p = 0.030). CONCLUSIONS: Phase angle predicts both arterial stiffness and vascular calcification in stable PD patients.