Peritoneal dialysis (PD) is a widely used modality of renal replacement therapy. Due to its continuous nature of therapy, better control of fluid status and preservation of residual renal function were presumed by most nephrologists. However, recent evidences showed that it might not be the case. The severity of fluid overloading and the need for anti-hypertensive agents to control blood pressure seems to be more severe for PD patients. Therefore, more aggressive strategy to control dry weight is mandatory in PD patients. However, over reduction of dry weight might affect residual renal function (RRF) and, probably, the survival of PD patients. A balance between reduction of dry weight and preservation of RRF is crucial for the care of PD patients. Currently, only clinical measures like cardiothoracic ratio on chest X-ray and absence of pedal edema were used to evaluate PD patient's dry weight. There is no objective method to determine dry weight accurately. In this prospective and randomized study, the investigators will use multi-frequency bio-impedance (MF-BIA) to detect intracellular and extracellular water (ECW) content of patients.

Inclusion Criteria:

• age 18 to 80

Exclusion Criteria:

• type I DM
• Severe heart failure
• unstable angina