This prospective, randomized, controlled study aims to evaluate the usefulness of the new body composition monitor (BCM) device as a method to improve volume control in hemodialysis (HD) patients and compare the results with those obtained by conventional volume control modalities.

The proposed prospective, randomized, controlled study intends to document the effect of volume control guided by BCM on blood pressure (determined both manually and 48-h ambulatory), need for anti-hypertensive medication, intra-dialytic complications, and left ventricular geometry and functions assessed by echocardiography. One hundred and seventy-six prevalent HD patients will be randomized into two arms: study group and control group.

In the study group, "overhydration (OH) in liters" will be estimated with the BCM (Body Composition Monitor, Fresenius Medical Care, Deutschland GmbH)at least once a month before a dialysis session in order to determine dry weight.

1. If OH is positive value, we will try to reach dry weight by ultrafiltration without regard to the level of blood pressure.

2. If OH is negative value , and:

   • Systolic blood pressure is < 100 mmHg with/or intradialytic hypotension episodes and/or clothing and/or erythrocytosis ( htc> 36 %); we will increase dry weight accordingly.
   • Systolic blood pressure is normal (100-150 mmHg) without intradialytic hypotension episodes and clothing and erythrocytosis; we will not change dry weight.
   • Systolic blood pressure normal (100-150 mmHg) with intradialytic hypotension episodes and/or clothing and/or erythrocytosis; we will increase dry weight.
   • Systolic blood pressure> 150 mmHg we will perform a captopril test (CT) If the CT is positive we will use ACE inhibitors / ARBs as anti hypertensive drugs and dry weight will be increased if intradialytic hypotension episodes and/or clothing and/or erythrocytosis ( htc> 36 %) are also present

If the CT is negative we will repeat the BCM measurement and if it gives same results we will perform ABPM for confirmation.

We will not need to reach the dry weight immediately. If severe BP drop precludes reaching DW in one session, an isolated ultrafiltration or additional dialysis session will be added.

In the control group, BCM results obtained at the beginning, at the 6th, and 12th months will not be given to the treating physicians. Dry weight estimation will be guided by clinical findings, telecardiography, and echocardiography as used to be.

The planned duration of the study is 12 months. All patients will be seen in every month during the study. Additional visits will be scheduled if any symptoms and intolerance are suspected.

Inclusion Criteria:

• Age older than 18-year,
• Maintenance bicarbonate HD scheduled thrice weekly (12 hours/week),
• Willingness to participate in the study with a written informed consent.

Exclusion Criteria:

• Presence of a cardiac stent, pacemaker or defibrillator ,
• Artificial joints, pin or amputation
• Permanent or temporary catheters (may affect BCM measurement),
• Being scheduled for living donor renal transplantation,
• Presence of serious life-limiting co-morbid situations, like malignancy, uncontrollable infection, end-stage cardiac, pulmonary, or hepatic disease,
• Pregnancy or lactating,
• Current use of investigational drugs or participation in an interventional clinical trial that contradicts or interferes with the therapies or measured outcomes in this trial,
• Mental incompetence.