Salt and fluid intake in the development of hypertension in peritoneal dialysis patients

Background. Although fluid overload contributes to hypertension in CAPD patients, less attention has been paid to the role of excess salt and fluid intake. Therefore, we investigated the role of salt and fluid intake in the development of hypertension in CAPD patients. Methods. A total of 165 stable CAPD patients were included into this study. Based on the blood pressure in three consecutive months, they were divided into three groups: persistent hypertensive (PH; n = 33), intercurrent hypertensive (IH; n = 58) and persistent normotensive (PN; n = 74). The IH group was further divided into two phases: normotensive and hypertensive. Fluid status was evaluated by clinical assessment and bioimpedance analysis (BIA). Results. There were no differences in age, gender, and duration of dialysis among groups. Patients were more fluid overloaded in the PH group. Extracellular water (ECW), total body water (TBW), and normalized extracellular water by height (NECW) were higher in the PH group than the PN group (16.77 +/- 3.62 L vs. 14.61 +/- 2.92 L for ECW, p < 0.01; 32.22 +/- 8.23 L vs. 28.98 +/- 6.00 L for TBW, p < 0.05; and 10.28 +/- 1.86 Urn vs. 9.08 +/- 1.63L/m for NECW, p < 0.01). However, patients in the PH group also had more total fluid removal (TFR) and total sodium removal (TSR) compared with the PN group (1346.82 +/- 431.27 mUd vs. 1139.28 +/- 412.65 mL/d for TFR, p < 0.05; and 141.52 +/- 61.57 mmol/d vs. 102.42 +/- 62.51 mmol/d for TSR, p < 0.01). The same trend was demonstrated when compared values of hypertensive and normotensive phase in IH group; patients had higher ECW, TBW, NECW, TSR, and PNa when they were in hypertensive phase than in the normotensive phase. Conclusions. This study confirmed that fluid overload was closely associated with the development of hypertension in CAPD patients. It also showed that hypertemive patients were in general more fluid overloaded despite a higher fluid and sodium removal as compared with normotensive patients.