A common but often overlooked cause of high blood pressure may be hiding in plain sight – and data from a pioneering wearable device could hold the key to its earlier diagnosis, according to new research.
The study, published in the journal Science Translational Medicine, concerns a condition called primary aldosteronism – a hormone disorder which affects up to one in five people with high blood pressure and puts them at higher risk of developing heart disease, stroke, diabetes, and other major health problems.
Researchers from the University of Bristol and the University of Manchester in the UK, the University of Bergen in Norway, and partners in Stockholm and Athens found that patients with the disorder experienced bursts of hormone production during the day as well as in the night while asleep, when routine blood testing is rarely carried out.
Thanks to an ingenious portable device, developed at the University of Bristol, the hormone levels of patients were able to be monitored round-the-clock in their homes rather than a hospital or research unit. This means hidden irregularities could be uncovered, which may normally go undetected by current testing methods, leading to earlier detection of health conditions.
Study co-lead author Dr Thomas Upton , Clinical Research Fellow in Automated Sampling Clinical Fellow at the University of Bristol, and Senior Clinical Fellow at Bristol Hospitals NHS Foundation Trust said: "Primary aldosteronism is an important cause of high blood pressure and the most common cause of secondary hypertension we see in our blood pressure clinic. It could be affecting millions of people in the UK. However, due to the way hormones change during the day and the current complexity of the diagnostic process, diagnosis is often delayed or never made at all.
"In our study, patients were monitored at home during normal activity, and this allowed us to see how hormones changed over time in realistic settings. This approach could potentially revolutionise how we diagnose hypertension and ultimately reduce cardiovascular disease – particularly heart disease and strokes – that could have been prevented."
The proof-of-concept investigation continuously monitored hormone levels every 20 minutes in 60 patients from Bristol, Bergen, Stockholm, and Athens, over a 24-hour period. The patients all wore a lightweight device – which is the size of a mobile phone and attaches at the waist – allowing hormones to be measured from the skin, while they carried out normal daily activities, including sleeping at night.
Called U-RHYTHM, the technology was adopted and advanced by the spinout company Dynamic Therapeutics in 2023.
Study senior author Dr Eder Zavala , UKRI Future Leader Fellow at the University of Manchester, said: "By continuously monitoring hormones over 24 hours, we were able to reveal a previously hidden pattern of nocturnal hormone bursts. This gives us a much clearer understanding of the disease and could ultimately help doctors detect it earlier and treat patients more effectively.
"A more detailed mathematical and computational analysis of daily hormonal profiles could eventually also help uncover earlier and more subtle forms of the disease, opening new opportunities to improve outcomes for patients living with high blood pressure."
Computational analysis of data from the device allowed researchers to track changes in aldosterone, the hormone responsible for regulating salt and water balance in humans, along with two closely related hormones known as 18-hydroxycortisol and 18-oxocortisol.
Existing tests may be missing patients because the study results showed aldosterone levels do not stay high all the time. Furthermore, the researchers found that even among some of the most severe cases of the disease, there were periods when hormone levels dipped below the minimum thresholds used to diagnose the condition.
Rather than finding persistently raised hormone levels, the researchers discovered repeated night-time bursts of hormone secretion while the day-night rhythm remained intact.
These hormone spikes, produced by the adrenal glands, were particularly prominent in patients whose disease was caused by a problem in only one adrenal gland rather than both. The abnormal hormone patterns disappeared after surgical removal of the affected adrenal gland, providing further evidence that the bursts were directly linked to the disease.
Study co-author Prof Stafford Lightman , Professor of Medicine at the University of Bristol and inventor of the U-RHYTHM technology, added: "The findings suggest that clinicians may need to rethink how they look for the disorder which the Endocrine Society clinical practice guidelines now recommend should be considered for all people with hypertension, also known as high blood pressure.
"Future diagnosis could move away from single time point blood tests and towards tracking the body's hormone rhythms over time, particularly the overnight patterns that appear to hold crucial clues to disease. Further research is needed to define the best clinical pathways, using dynamic hormone measurement, to ensure early diagnosis of this common and potentially curable cause of high blood pressure."
The research was funded by EU Horizon 2020, the Trond Mohn Foundation, the UKRI Biotechnology and Biological Sciences Research Council (BBSRC), Medical Research Council, University Hospitals Bristol and Weston NHS Foundation, the Swedish Medical Research Council and Knut and Alice Wallenberg Foundation.
The findings support the University of Bristol's research 'Grand Challenge' focus on Understanding and Preventing Cardiovascular Disease and builds on NIHR-funded initiatives aimed at earlier identification of people with hypertension and other cardiovascular risk factors.
Paper
'Tissue corticosteroid rhythms are dysregulated predominantly during sleep in primary aldosteronism' by M.A. Grytaas et al. in Science Translational Medicine
