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Haemodialysis Salt Reduction Study

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00141609
Recruitment Status : Completed
First Posted : September 1, 2005
Last Update Posted : May 14, 2007
Information provided by:
St George's, University of London

Brief Summary:

High blood pressure (hypertension) affects up to 80% of all patients receiving haemodialysis for chronic kidney disease (CKD). High blood pressure is a major cause cardiovascular disease (i.e. strokes, heart attacks and heart failure) and, thereby, cardiovascular deaths in these patients.

A significant cause of raised blood pressure in haemodialysis patients is thought to be due to retention of salt in the body. In healthy people the kidneys excrete salt but the kidneys of patients with CKD cannot do this, so salt has to be removed by dialysis. However dialysis cannot remove as much salt as is necessary, and so it accumulates. This fact has been recognized for many years, and health professionals caring for haemodialysis patients often stress the importance of restriction of dietary salt intake.

However no research has looked in detail at the mechanisms by which salt raises blood pressure in haemodialysis patients. It is likely that salt directly affects thirst, causing patients to drink more and become overloaded with fluid. In addition, salt may have direct effects on the blood vessel wall, causing failure of adequate blood vessel relaxation. Both of these factors may raise blood pressure.

We will conduct a carefully controlled crossover study looking at the effects of a modest reduction in salt intake on BP. During the course of the study, which will last eight weeks, patients will receive both a 5 gram per day and a 10 gram per day salt intake. We will look at how thirst, fluid intake, a number of markers of blood vessel function and blood pressure differ on these two salt intakes.

Condition or disease Intervention/treatment Phase
Kidney Failure, Chronic Hypertension Drug: Slow Sodium Not Applicable

Detailed Description:

High blood pressure (BP) is a major independent risk factor for cardiovascular mortality in individuals on haemodialysis, and yet BP is extremely poorly controlled in this population.

Excessive dietary salt intake is likely to be a major cause of hypertension in these patients. Firstly, excessive salt intake will result in thirst, excessive fluid intake and weight gains between dialysis, and thereby chronic over-expansion of extracellular fluid volumes resulting in high blood pressure. Secondly, salt may have direct effects on the arterial tree contributing to endothelial dysfunction that has clearly been demonstrated in uraemic individuals, including haemodialysis patients. Abnormalities in endothelial nitric oxide (NO) production may play an important role in salt-sensitive hypertension, mediated by the potent inhibitor of NO synthase, asymmetrical dimethylarginine (ADMA). Plasma ADMA concentrations are several-fold higher in individuals on dialysis than in normal controls, and it would be of interest to see whether ADMA concentrations decrease with a reduction dietary salt intake.

In spite of the importance of dietary salt intake in haemodialysis patients, there are no controlled studies which delineate the mechanisms by which salt intake affects BP. We propose to conduct a prospective double-blind placebo controlled cross-over study of normal (10 to 12 grams salt per day) versus modestly reduced (6 grams per day) salt intake over an eight week period in haemodialysis patients. The primary outcome measure is the change in pre-dialysis systolic BP. Other outcome measures include mean systolic and diastolic BP as measured by ABPM, thirst scores, daily weight gains and thoracic fluid content, as measured by thoracic bioimpedance. Furthermore, in a sub-group of subjects will we study the changes in plasma ADMA concentrations with reductions in salt intake, and examine correlations with changes in BP and systemic vascular resistance.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 20 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double
Primary Purpose: Treatment
Official Title: A Study Looking at the Effects of a Modest Reduction in Dietary Salt Intake on Blood Pressure Control in Haemodialysis Patients
Study Start Date : April 2004
Study Completion Date : October 2006

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Dialysis Sodium

Primary Outcome Measures :
  1. Change in pre-dialysis systolic blood pressure

Secondary Outcome Measures :
  1. Change in post-dialysis ambulatory BP (24 hr)
  2. Change in thirst score
  3. Change in intra-dialytic weight gain
  4. Change in systemic vascular resistance
  5. Change in assymmetric dimethylarginine (ADMA)

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 85 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Haemodialysis/haemodiafiltration for ESRF for >3 months
  • Clinically stable

Exclusion Criteria:

  • Significant intercurrent illness
  • Systolic BP >240 mmHg/diastolic BP >120 mmHg at enrollment
  • Unstable blood pressure whilst on HD
  • Sodium profiled haemodialysis/HDF

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00141609

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United Kingdom
Blood Pressure Unit, Cardiac & Vascular Sciences, SGUL
London, United Kingdom, SW17 0RE
Sponsors and Collaborators
St George's, University of London
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Principal Investigator: Timothy WR Doulton, MBBS BSc MRCP SGUL
Publications automatically indexed to this study by Identifier (NCT Number):
Layout table for additonal information Identifier: NCT00141609    
Other Study ID Numbers: LREC 04.0013
First Posted: September 1, 2005    Key Record Dates
Last Update Posted: May 14, 2007
Last Verified: May 2007
Keywords provided by St George's, University of London:
End-stage renal failure
Blood Pressure
Additional relevant MeSH terms:
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Renal Insufficiency
Kidney Failure, Chronic
Kidney Diseases
Urologic Diseases
Renal Insufficiency, Chronic