Hypertension remains one of the most common health problems worldwide, and for many patients it is difficult to control despite treatment. A recent imaging advance could help doctors more quickly identify an often-overlooked hormonal cause and choose the right treatment.
A new type of scan, lasting just ten minutes, could improve treatment for millions of people with high blood pressure, according to a study led by researchers at University College London (UCL) and published on Wednesday in New England Journal of Medicine – NEJM.
About a quarter of patients with high blood pressure may have adrenal glands that produce too much aldosterone, a hormone that regulates salt balance in the body. Excess aldosterone increases blood pressure through sodium and water retention and can lead to primary hyperaldosteronism, also known as Conn’s syndrome, a condition associated with increased risk of heart disease, stroke and deterioration of kidney function.
However, the researchers point out that there are probably many patients who do not meet the classic criteria for primary hyperaldosteronism, but still have an elevated aldosterone level that keeps their blood pressure high.
Currently, finding this cause is complicated: screening is done through a blood test, followed by a confirmatory test, and treatment usually requires an invasive procedure called adrenal vein catheterization.
This involves inserting two catheters through groin veins to measure aldosterone on each side of the body, with the aim of determining whether the excess is coming from just one adrenal gland or both. The procedure is technically difficult, available in few centers and does not always provide reliable results, which is why a significant number of cases remain undiagnosed.
The new test uses PET-CT, a technique that combines computed tomography (CT) with positron emission tomography (PET), providing detailed 3D images and tracking the distribution of an intravenously injected radioactive tracer.
The UCL team developed the new substance, designed to selectively bind to aldosterone synthase, the enzyme that produces aldosterone.
In the scanning procedure, the tracer preferentially accumulates in areas of the adrenal gland that excessively secrete the hormone, making them visible, even when classic tests do not detect this problem.
In the first clinical trial with this method, carried out at UCLH, 17 patients were investigated, and the source of excessive aldosterone production was identified in each of them, with no observable side effects.
The researchers say that this direct visualization technique of the hormonal “hot spot” would greatly simplify the therapeutic decision: either by surgical removal of the responsible adrenal, when the problem occurs in only one of the glands, or targeted drug treatment that blocks the production of aldosterone, when both glands are involved.
Professor Bryan Williams, clinical coordinator of the study and chair of the Department of Medicine at UCL, says such a test has been awaited for decades and could substantially change the way excess aldosterone is diagnosed, an important and often undiagnosed cause of hypertension.
The intensity of the signal on the scan seems to reflect the level of hormonal overproduction, which could allow for more precise treatments in the future, aimed directly at hyperactive areas.
The innovation comes after more than ten years of research by the team from UCL, which developed and patented the method of obtaining radioactive tracers. With this technology, the researchers adapted a molecule with a drug-like structure that binds to the aldosterone-producing enzyme, replacing a single atom with a radioactive variant of it, so that the compound could be tracked on PET-CT.
The team is now preparing a phase 2 clinical trial to collect the data necessary to approve the test for routine use in the British health system (NHS).
In the UK, it is estimated that more than 14 million people have high blood pressure, around one in three adults, and quickly identifying a treatable hormonal cause could have a major impact on disease control and the risk of cardiovascular and kidney complications.