A 24-hour wearable uncovered nighttime hormone bursts in primary aldosteronism

The discovery

The researchers asked whether primary aldosteronism produces time-dependent hormone patterns that are invisible to isolated daytime blood tests, and whether 24-hour ambulatory sampling could detect those patterns during normal life and sleep.

The research question and why it matters

Current primary-aldosteronism screening relies on aldosterone and renin measurements, followed by additional testing when appropriate. Earlier U-RHYTHM work showed that portable microdialysis could obtain high-resolution daily steroid profiles. This study applied that approach to primary aldosteronism and connected dynamic profiles with adrenal disease subtype and surgery.

What researchers found

Aldosterone was not simply elevated at a steady level. It appeared in repeated bursts during the day and at night while the overall day-night rhythm remained present. Nighttime bursts were especially prominent when excess production came from one adrenal gland. Some severe cases also passed below diagnostic concentration thresholds at parts of the day, and the abnormal profiles disappeared after surgery in the observed unilateral cases.

Results at a glance

Key results from the tested systems

participants

People with primary aldosteronism were monitored across four European cities.

24 hours

monitoring period

Sampling continued through ordinary activity and sleep.

20 min

sample interval

Dense measurements revealed brief rises and falls hidden by snapshots.

steroids measured

Aldosterone, 18-hydroxycortisol and 18-oxocortisol were tracked.

How the research worked

Participants wore the waist-mounted U-RHYTHM sampler at home for 24 hours. It collected samples through the skin every 20 minutes while participants followed their usual routines. The team measured aldosterone and the related steroids 18-hydroxycortisol and 18-oxocortisol, then used computational analyses to identify daily rhythms and short secretion bursts. Patterns were compared across forms of primary aldosteronism and, where available, before and after removal of an affected adrenal gland.

Subjects or systemHuman

Research designMulticenter proof-of-concept repeated-measures study using ambulatory 24-hour hormone sampling and computational rhythm analysis

Evidence baseSixty people with primary aldosteronism monitored in Bristol, Bergen, Stockholm and Athens; hormones were sampled every 20 minutes during usual activity and sleep over one 24-hour period

How to interpret this design

The design determines what kind of conclusion the evidence can support. Direct measurement strengthens the reported observation, while generalization beyond the tested subjects, material, place or conditions requires additional evidence.

Because the research involved people, it speaks directly to the participants and outcomes measured. It may still apply differently to people outside the eligibility criteria, age range, clinical setting, geography or follow-up period.

What strengthens or limits the finding?

The study repeatedly measured three adrenal steroids in everyday conditions, compared patterns across disease subtypes and observed the abnormal pattern disappear after surgery in affected participants. It was a 60-person proof-of-concept investigation and did not prospectively test diagnostic accuracy against current care.

This is an early signal that deserves attention and replication, not a result that should yet carry the weight of mature, independently confirmed research.

Funding and disclosure context

The recorded funding source is: European Union Horizon 2020, Trond Mohn Foundation, UKRI Biotechnology and Biological Sciences Research Council, UK Medical Research Council, University Hospitals Bristol and Weston NHS Foundation Trust, Swedish Medical Research Council and Knut and Alice Wallenberg Foundation. The recorded conflict information is: The primary-paper metadata identifies Stafford L. Lightman as a cofounder of Dynamic Therapeutics, the company developing the U-RHYTHM technology. The University of Bristol also identifies him as the device inventor and says the technology was adopted by the spinout in 2023.. Funding or a disclosed relationship does not by itself invalidate a result, but it is relevant when judging design choices, analysis and the need for independent replication.

What it means

The work shows why the timing of a hormone measurement may matter. Dense overnight profiles could eventually supplement current aldosterone-and-renin testing or help researchers design better sampling schedules. They are not yet a replacement for guideline-based screening, confirmatory testing, imaging or adrenal-vein sampling, and patients should not change care based on this study.

Beyond the abstract

Deeper analysis

A snapshot can miss a pulse

Endocrine glands often release hormones in bursts. A blood draw records only the concentration at that instant, so a patient can cross above and below a decision threshold without the underlying disease switching on and off.

Within-person resolution is the study’s strength

Sampling every 20 minutes produced roughly three observations per hour instead of one clinic value. That density supports rhythm analysis, although many observations from one participant do not substitute for a larger number of independent patients.

Surgery is supportive, not a complete validation

The disappearance of an abnormal pattern after an affected gland was removed strengthens the link to unilateral disease. It does not by itself establish how accurately the pattern identifies candidates for surgery.

The clinical test still has to be built

A useful diagnostic pathway needs prespecified thresholds, repeatability, comparison with accepted reference tests, practical costs and evidence that acting on the result helps patients. Those steps remain ahead.

Keep the claim in proportion

What it does NOT prove

It does not show that a single normal aldosterone result rules primary aldosteronism in or out.
It does not establish the sensitivity, specificity or error rate of U-RHYTHM as a diagnostic test.
It does not prove that nighttime sampling improves cardiovascular outcomes or reduces missed diagnoses.
It does not show that every person with hypertension should undergo 24-hour wearable hormone monitoring.
It does not justify changing medication, salt intake or testing without a clinician.

Important limitations

Sixty participants are enough to reveal repeated within-person patterns but too few to define population-wide diagnostic thresholds.
Monitoring covered one 24-hour period, so day-to-day reproducibility remains uncertain.
The public report did not provide complete counts for each disease subtype or the post-surgery subgroup.
A proof-of-concept physiology study is not the same as a prospective diagnostic-accuracy trial against an independent clinical standard.
Sleep, posture, meals, medication and sampling conditions can affect hormone rhythms and require careful standardization in future use.
An inventor and company cofounder relationship is directly relevant because the proposed application depends on the U-RHYTHM device.

How this fits with previous research

Questions still unanswered

Do the nighttime patterns reproduce on multiple days in the same person?
Which features of a 24-hour profile best distinguish primary aldosteronism from primary hypertension?
Can a shorter or less intensive sampling schedule provide the same diagnostic information?
How do medications, sleep disorders, shift work and kidney function alter the profiles?
Would dynamic testing find more treatable cases or improve health outcomes in a prospective clinical trial?

Government verification and context

Relevant U.S. government resources

These resources serve different purposes. A registry can verify what researchers planned, a repository can locate government-funded work, and an agency page can supply authoritative background. None automatically proves that this paper's conclusion is correct.

Study verificationNational Library of Medicine / NIH

PubMed record search ↗

Federal biomedical-index search keyed to this paper's DOI or title. It can confirm indexing and expose linked identifiers when a record is available; the journal paper remains the primary source.

Authoritative contextNational Institutes of Health

Understanding clinical research ↗

NIH background on how clinical research is designed, reviewed and interpreted. This is contextual guidance, not independent confirmation of the study's result.

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Sources and provenance