A hidden hormone disorder may explain 1 in 5 cases of high blood pressure

A hormone disorder called primary aldosteronism may be driving as many as 1 in 5 cases of high blood pressure, according to researchers at the University of Bristol who tracked patients with a wearable hormone monitor instead of a single blood draw. The condition starts in the adrenal glands, small organs that sit above each kidney and help regulate blood pressure by releasing the hormone aldosterone.

Standard testing typically catches only one blood sample at one moment in the day, and that snapshot approach is exactly what the Bristol team says has let so many cases slip past diagnosis for years. Applied to the roughly 119.9 million American adults the CDC counts as hypertensive, a 1-in-5 estimate points to tens of millions of cases a routine test could be missing entirely.

A wearable device caught what a single blood draw misses

The research team, led by Dr. Thomas Upton of Bristol alongside Dr. Eder Zavala of the University of Manchester and Prof. Stafford Lightman, fitted 60 patients with a waist-worn device called U-RHYTHM, described in the underlying paper in Science Translational Medicine. Lightman, who invented the U-RHYTHM technology, built it to solve a problem simpler devices could not: capturing hormone changes as they happen rather than relying on a single number drawn at whatever hour a patient could get to a clinic. The device sampled hormone levels every 20 minutes over a full 24-hour stretch while patients went about ordinary routines, including sleep, rather than sitting still for a single clinic-hours draw taken whenever an appointment happened to land.

Patients were recruited across four cities — Bristol, Bergen, Stockholm and Athens — giving the study a geographic spread beyond a single hospital’s patient pool, according to the University of Bristol’s announcement of the findings. That multi-site design let the team compare hormone rhythms across different populations rather than risk a result specific to one hospital’s testing routine.

Aldosterone spikes at night, when nobody is testing

The continuous readings turned up nighttime bursts of aldosterone that a daytime clinic visit would never catch. Even in some of the most severe cases, hormone levels sometimes dropped below the minimum thresholds typically used to diagnose primary aldosteronism, meaning a standard test performed at the wrong hour can return a falsely reassuring result for a patient who genuinely has the disorder.

Upton put the diagnostic gap plainly: “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.” A conventional aldosterone-to-renin blood test, drawn once in the morning, simply cannot see a spike that happens hours later while a patient sleeps, which is the specific timing problem the wearable device was built to solve.

Scaling a 1-in-5 estimate up across millions of hypertension patients

Primary aldosteronism is treatable, and often curable, when it is caught. That makes the diagnostic gap costly in a specific way: the condition is separately linked to a higher risk of heart disease, stroke and diabetes, complications that a targeted treatment could reduce if doctors knew to look for it in the first place. The CDC’s own figures put hypertension at 119.9 million American adults, a base large enough that even a modest fraction being misdiagnosed represents a sizable undiagnosed population nationwide.

A companion perspective published in the same Science Translational Medicine issue frames primary aldosteronism as part of a broader pattern in adrenal disease, where hormone rhythms rather than fixed hormone levels carry the diagnostic signal doctors have historically overlooked in favor of a single measured value.

Surgery reversed the abnormal pattern in affected patients

For patients whose primary aldosteronism traced to a single overactive adrenal gland, the abnormal hormone pattern disappeared after that gland was surgically removed, the Bristol researchers found. That result, drawn from the same wearable-monitoring data, is what lets Upton’s team argue the disorder is not just detectable with better tools but correctable once it is found and localized to one gland rather than both.

The 60-patient study is a proof of concept rather than a population-wide screening rollout, and the researchers have not said when or whether wearable hormone monitoring might become standard practice for the millions of hypertension patients whose case never gets this close a look. Bringing a device like U-RHYTHM into routine primary care would mean scaling up manufacturing, training clinicians to interpret a full day of readings instead of one number, and building the cost case for insurers to cover it. ScienceDaily’s write-up of the findings frames that open question as the study’s next test: whether a device built for a four-city research cohort can scale to the kind of routine care that reaches the broader hypertensive population.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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