Using modern technology to improve the diagnosis of common conditions – A blog by Professor Brian Keevil
In his blog, Professor Brian Keevil Clinical Lead for Biochemistry at Wythenshawe Hospital, part of Manchester University NHS Foundation Trust (MFT) discusses the development of a pioneering at-home test that could save lives.
Devised at MFT, the test uses saliva rather than blood to provide a simpler, quicker way to diagnose adrenal insufficiency – a common disorder caused by the lack of the body’s main stress hormone, cortisol.
The importance of measuring cortisol
Cortisol is an important steroid hormone produced by the body in times of stress and is necessary for survival after trauma. It has several functions, including helping to regulate blood pressure and the immune system, as well as balancing the effect of insulin to keep blood sugar normal.
Adrenal insufficiency occurs when the body is unable to make cortisol. This is a common disorder that affects around 50 per cent of people taking anti-inflammatory steroid treatment for conditions such as asthma, arthritis and inflammatory bowel disease. Adrenal insufficiency can affect the body’s ability to respond to stress and maintain other essential life functions.
As saliva samples are easier to collect than blood samples, the biochemistry team at MFT pioneered a method for measuring cortisol in saliva samples instead of blood samples nearly 15 years ago. Over that time we have gathered evidence to show the accuracy and usefulness of the saliva-based test, which we believe will change future practice.
Development of the saliva method
A saliva test has great potential because its simplicity and convenience allows patients to take samples at home, rather than attend hospital, which is necessary when taking blood for testing. The hospital also benefits because it saves on staffing time, outpatient appointments and drug costs.
In a study delivered with Sheffield Teaching Hospitals NHS Foundation Trust and the University of Sheffield, and reported in the New England Journal of Medicine Evidence, 200 patients attending Sheffield Teaching Hospitals, who were identified as being at risk of adrenal insufficiency were given the at-home saliva test kit.
All patients recruited into the study, which was funded by the National Institute for Health and Care Research, were simultaneously tested for their cortisol using the standard hospital-based screening procedure. Results showed that the home test was able to make an accurate diagnosis in 70 per cent of patients at risk of adrenal insufficiency.
Patients also reported that they found taking the test at home helped to reduce their anxiety, with the added benefit of improving their overall health and reducing the time they had to take off work. The rapid diagnosis also meant that patients were able to be treated imminently and avert an adrenal crisis (symptoms of which include dizziness, weakness, abdominal pain, nausea and vomiting, or even loss of consciousness) which can be fatal if untreated.
The test is now being considered for roll out across the NHS and worldwide.
Our next steps are to investigate the use of saliva cortisone to detect cortisol excess – linked to increased risk of heart disease, lung issues, obesity, anxiety, depression, and more. Cortisol excess mostly affects people who have been taking steroid medicine, especially steroid tablets, for a long time, but has also been associated with the newly recognised condition mild autonomous cortisol secretion (MACS) identified in patients with benign tumours of the adrenal gland.
We already use a sample taken at midnight, when cortisol production should be at its lowest, to help in diagnosing cortisol excess, but one of the confirmatory tests is to give a powerful steroid (dexamethasone) overnight which should suppress cortisol production in normal patients but not in those with cortisol excess.
This requires the patient to attend clinic the following morning after taking the steroid to have a blood sample taken. The ability to carry out a saliva test at home instead would again simplify the process and have a significant impact on the investigation and treatment of this condition.
These developments are exciting because we are using modern technology to improve the diagnosis of common conditions, save vital resources and make the patient journey a little easier.