Introduction: Chronic kidney disease is characterized by a progressive deterioration of renal function. At the end of the progression, when complications occur (overhydration, electrolyte imbalances or retention of uremic toxins), a percentage of patients requiring renal replacement therapy (haemodialysis). When starting the haemodialysis, the patient holds the residual renal function (RRF) which is lost over time. To preserve the RRF, the patient is treated with diuretics loops and / or thiazide diuretics. The effect of this treatment is lost when renal function worsens. In this context, there are few studies that explore the use and effectiveness of diuretics in patients on haemodialysis 2. Objectives and Hypothesis:

Hypothesis: The treatment with furosemide and hydrochlorothiazide in haemodialysis patients with RRF could:

• To decrease in weight gain between haemodialysis sessions.
• To increase urine volume.
• To decrease the ultrafiltration in haemodialysis sessions ( the long interdialytic interval)

Main Objective:To asses the effect of combined hydrochlorothiazide-furosemide therapy on gain weight between haemodialysis sessions in patients with RRF

Secondary Objective: To asses the effect of combined hydrochlorothiazide-furosemide therapy on dialytic, clinical and analytical variables and use of the antihypertensive treatment

3. Methodology: Randomized open clinical trial to compare the effectiveness of the administration of diuretics in haemodialysis patients with residual renal function in single centre.

The population of study are patients with chronic renal disease in haemodialysis therapy that they preserve residual renal function ( more 200ml daily of urine). It will be a simple randomization, to asses the effect of combined hydrochlorothiazide-furosemide therapy

After a of 15 days washout without diuretic treatment, patients will be randomized to receive or not receive combined diuretic treatment for 1 month. After a 1 month washout , the patients will be receive or not the treatment according to cross over trial.

Inclusion Criteria:

• Over 18 years
• Chronic kidney disease, stage 5 Chronic Kidney Disease, in haemodialysis
• Renal residual function preserved(more or equal 200 ml daily of urine)
• Minimum 3 months on haemodialysis and wish to participate in this study

Exclusion criteria:

• Less 4 millequivalent of potassium plasma in interdialytic sessions or to require potassium intradialytic treatment.
• Less 1 Kg of gain weight in the long interdialytic interval.
• Adverse effects with treatment in the past.
• To refusal to participate in the study.
• Pregnancy or lactation period.
• Contraindication the use of diuretic therapy, according to pharmacological profile.