Condition category
Urological and Genital Diseases
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Background and study aims
The kidneys are important in controlling the levels of many different chemical levels in the blood. They also control the amount of salt (sodium) and water in the body, which in turn can affect blood pressure. If the kidneys are not working properly, a condition called chronic kidney disease, blood pressure can be high. This is called hypertension. Hypertension can cause further damage to the kidneys and also damage the heart and blood vessels. Controlling high blood pressure is a very important part of looking after chronic kidney disease.
Acid levels can also build up in the blood in chronic kidney disease. Doctors often prescribe tablets called sodium bicarbonate (which is bicarbonate of soda, or baking powder in tablet form) to correct acid levels. Because these tablets contain sodium, there is a possibility that they could have an effect on sodium and water retention or blood pressure in people with kidney disease. The aim of this study is to try and measure the effects of sodium bicarbonate on body water in people with chronic kidney disease.

Who can participate?
Adults with chronic kidney disease

What does the study involve?
The study involves having measurements of blood pressure and body water at two time points, 4weeks apart. In the 4-week interval between the measurements, participants will take three extra tablets three times a day. Body water is measured in two ways. One method involves a simple electric test called bioimpedance. Bioimpedance uses a small electric current that is passed between two electrodes placed on the back of one hand and two electrodes placed on the top of one foot, while lying comfortably on a couch. The electric current is very low, cannot be felt and is completely safe. The other method involves drinking two small beakers of colourless liquid. One tastes just like water. The other is slightly salty. Both are harmless. A sample of blood and saliva are taken just before the drinks. A further blood sample is taken 4 hours after the drinks and further saliva samples at 4, 5 and 6 hours after the drinks. Participants also agree to provide a record of their blood pressure medication and to provide a 24-hour urine collection at the beginning and end of the study.

What are the possible benefits and risks of participating?
There are no immediate health benefits to taking part. Participants are helping us to understand their medical condition more fully and this might lead to better or safer treatment in the future.
It is possible that participants could retain fluid or have an increase in blood pressure. The study is short and any changes will be picked up by the study team. Any changes should be temporary and go away at the end of the study.

Where is the study run from?
York Hospital

When is the study starting and how long is it expected to run for?
June 2007 to November 2011

Who is funding the study?
British Renal Society (UK)

Who is the main contact?
Dr Colin Jones,

Trial website

Contact information



Primary contact

Dr Colin Jones


Contact details

York Hospital
Wigginton Road
YO31 8HE
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

The effects of oral sodium bicarbonate on extracellular water in patients with chronic renal failure


Study hypothesis

Does oral sodium bicarbonate have an effect on extracellular water or blood pressure in patients with chronic kidney disease?

On 14/02/2012 an update was received stating that the trial end date was extended following a trial halt period. Trial was terminated early on 21/11/2011 at 40 subjects due to inability to recruit sufficient patients within a reasonable timescale. Relevant authorities have been notified. Sample analysis is currently taking place. Statistical analysis and publication of results will follow later this year.

On 15/02/2012 the overall trial end date was changed from 30/09/2008 to 21/11/2011.

Ethics approval

Hull and East Riding Local Research Ethics Committee, 21/08/2006, ref: 06/Q1104/108

Study design

Randomised double-blind placebo-controlled trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet.


Chronic kidney disease


Oral sodium bicarbonate 1.5 g three times a day for 4 weeks versus placebo. Follow up is complete at the end of the 4-week treatment period.

Intervention type



Not Applicable

Drug names

Sodium bicarbonate

Primary outcome measure

Extracellular water and total body water measured by bromide space and deuterium dilution at 4 weeks.

Secondary outcome measures

The following will be assessed at 4 weeks:
1. Blood pressure
2. Bio-impedance measures of total body water (TBW) and extracellular fluid (ECF)

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Chronic kidney disease (CKD) (creatinine greater than 180 mcmol/l or glomerular filtration rate [GFR] less than 60 ml/min)
2. Aged over 18 years, male and female

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Need for dialysis
2. Already taking oral sodium bicarbonate
3. Uncontrolled hypertension
4. Peripheral oedema
5. Nephrotic syndrome
6. Congestive cardiac failure

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

York Hospital
Wigginton Rd
YO31 8HE
United Kingdom

Trial participating centre

St James's University Hospital
Beckett Street
United Kingdom

Sponsor information


York Hospitals NHS Trust (UK)

Sponsor details

York Hospital
Wigginton Road
YO31 8HE
United Kingdom

Sponsor type




Funder type


Funder name

British Renal Society (UK) (ref: 05-008)

Alternative name(s)


Funding Body Type

private sector organisation

Funding Body Subtype

Associations and societies (private and public)


United Kingdom

Results and Publications

Publication and dissemination plan

Not provided at time of registration

IPD sharing statement:
The datasets generated during and/or analysed during the current study are not expected to be made available because this was not part of the consent process.

Intention to publish date

Participant level data

Not expected to be available

Basic results (scientific)

Publication list

2019 results in (added 01/03/2019)

Publication citations

Additional files

Editorial Notes

01/03/2019: Publication reference added. 24/01/2019: The following changes have been made: 1. The public title has been changed from "The effects of oral sodium bicarbonate on extracellular water in patients with chronic renal failure" to "Does bicarbonate of soda affect water balance when it is prescribed to treat people with kidney failure? ". 2. A plain English summary has been added. 3. St James's University Hospital has been added as a trial participating centre. 4. An IPD sharing statement has been added. 07/06/2017: No publications found in PubMed, verifying study status with principal investigator.