Condition category
Circulatory System
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Not provided at time of registration

Trial website

Contact information



Primary contact

Dr Karen Mullan


Contact details

Royal Victoria Hospital
Grosvenor Road
BT12 6BA
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

The renin-angiotensin-aldosterone (RAAS) axis, endothelial function and hypertension: diagnostic strategies, and therapeutic role of potassium supplementation - a randomised cross-over trial and an observational study


Study hypothesis

Study 1:
We seek to test the hypothesis that endothelial function is improved when dietary potassium is supplemented in a group with moderate risk of developing cardiovascular disease. We also wish to assess the effect of this supplementation on the renin-angiotensin-aldosterone (RAAS) axis and the effect of any of these changes on proinflammatory cytokines and adhesion molecules.

Study 2:
We seek to test the hypothesis that the synacthen test can be used to distinguish patients with primary (essential) hypertension from those with secondary hypertension due to hyperaldosteronism (due to Conn's adenoma or bilateral adrenalhyperplasia). We will also assess the aldosterone response to gonadotropin releasing hormone (GnRH) in healthy volunteers and patients with hyperaldosteronism.

Ethics approval

Office for Research Ethics Committees Northern Ireland
Study 1 approved on 02/09/2008 (ref. 08/NIR08/54)
Study 2 approved on 19/08/2008 (ref. 08/NIR08/55)

Study design

Study 1: Prospective randomised cross-over investigator-blinded trial
Study 2: Observational study

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


Hypertension, cardiovascular risk, hyperaldosteronism


Study 1: Dietary intake of sodium and potassium will be assessed and a 24 hour urine collection for estimation of Na and K excretion will be taken. The subjects will be randomised to either placebo or potassium supplementation (4.8 g/day; oral) for 6 weeks. There will be a 6 week washout period. Subjects will be studied at baseline, at the end of washout and after each intervention (4 in total).

Study 2:
The target numbers of participants for the three groups are as follows:
i. Patients with essential hypertension: n = 20
ii. Patients with hyperaldosteronism: n = 8
iii. Healthy volunteers: n = 15
43 participants in total

Patients with essential hypertension and patients with hyperaldosteronism will undergo a 250 mcg synacthen test with blood and saliva sampled at 0, 30 and 60 mins for cortisol and aldosterone. This test will be performed after 30 min of recumbency. In addition the healthy volunteers and patients with hyperaldosteronism will also undergo a GnRH test to assess aldosterone response.

Intervention type



Not Applicable

Drug names


Primary outcome measure

Study 1 - Global endothelial function assessed by determining the change in augmentation index (AIx) in response to the administration of nitroglycerin (NTG) and salbutamol.
Study 2 - Aldosterone response to synacthen/GnRH

All primary and secondary outcomes for Study 1 will be assessed at baseline, at the end of washout and after each intervention.

Secondary outcome measures

Study 1 - Brachial blood pressure, pulse wave velocity, serum potassium, renal function, lipid profile, plasma renin activity and aldosterone levels (taken after at least 30 minutes recumbency). Circulating markers of endothelial function (E selectin, VCAM-1, ICAM-1) and markers of inflammation (IL-6, IL-1 beta, hsCRP)

All primary and secondary outcomes for Study 1 will be assessed at baseline, at the end of washout and after each intervention.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Study 1:
1.1. Patients (both males and females) aged 40-70 with moderate (>10%) cardiovascular disease risk (Joint British Societies' [JSB2] guidelines)

Study 2:
Three groups of participants (both males and females, all within age 18-70):
2.1. Patients with essential hypertension
2.2. Patients with hyperaldosteronism
2.3. Healthy volunteers

Participant type

Healthy volunteer

Age group




Target number of participants

83 (Study 1: 40, Study 2: 43)

Participant exclusion criteria

Study 1:
1.1. A history or renal or cardiovascular disease
1.2. Fasting glucose >7 mmol/l
1.3. Serum potassium >5.5 mmol/l
1.4. Treated seated blood pressure >140/90 mmHg
1.5. Women on hormone replacement therapy (HRT)
1.6. Pregnancy

Study 2:
2.1. Pregnancy

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Royal Victoria Hospital
BT12 6BA
United Kingdom

Sponsor information


Royal Victoria Hospital (UK)

Sponsor details

Grosvenor Road
BT12 6BA
United Kingdom

Sponsor type

Hospital/treatment centre



Funder type


Funder name

Northern Ireland Research and Development Office (UK) (ref: EAT/3740/07)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

12/07/2016: No publications found, verifying study status with principal investigator.