Primary aldosteronism, a potentially curable hormone disorder driving hidden cases of high blood pressure, often escapes detection by standard single-sample blood tests because the underlying hormone surges fluctuate throughout the day and night, according to a study published in Science Translational Medicine. Researchers found that continuous monitoring via wearable devices can capture these missed diagnostic signals, shedding light on a condition that may affect up to one in five people with hypertension.
How Wearable Technology Detects Hidden Hormone Surges
Standard diagnostic workups for secondary hypertension typically rely on a single blood sample drawn during a clinic visit. However, researchers from the University of Bristol, the University of Manchester, the University of Bergen, and partner institutions in Stockholm and Athens discovered that aldosterone production does not stay continuously elevated. Instead, it repeatedly climbs and falls throughout a 24-hour cycle.
In a proof-of-concept investigation involving 60 patients across Bristol, Bergen, Stockholm, and Athens, scientists utilized a portable device called U-RHYTHM to track hormone patterns. Developed by the University of Bristol and adopted by the spinout company Dynamic Therapeutics in 2023, the lightweight, mobile-phone-sized monitor attaches to the patient’s waist and records hormone levels from the skin every 20 minutes.
According to computational analysis of the data, patients experienced brief surges of aldosterone, 18-hydroxycortisol, and 18-oxocortisol during waking hours and while sleeping. At various points, hormone concentrations dropped below the minimum thresholds required for a standard clinical diagnosis, which explains why isolated blood draws frequently yield false negatives even in patients with severe disease.
Clinical Implications for Resistant Hypertension
Primary aldosteronism occurs when the adrenal glands produce an excess of aldosterone, disrupting the body’s balance of salt, water, and blood pressure. Individuals with the untreated disorder face significantly elevated risks of stroke, heart disease, and diabetes.
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, noted the diagnostic hurdles in a statement. Primary aldosteronism represents the most common cause of secondary hypertension seen in specialized blood pressure clinics, potentially affecting millions of people in the UK alone. Because hormone levels shift unpredictably during the day, continuous home monitoring provides a clearer picture of realistic physiological activity compared to artificial hospital or research environments.
Next Steps in Hypertension Diagnostics
The ability to capture nighttime hormone secretion—activity traditionally missed because routine blood draws rarely occur while patients sleep—opens new avenues for clinical evaluation. Researchers indicate that integrating continuous ambulatory monitoring into routine care could fundamentally change how physicians diagnose secondary hypertension. By identifying hidden cases of primary aldosteronism early, medical teams aim to target specific treatments more effectively and reduce preventable cardiovascular complications.
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