In the UK approximately 12 million individuals are diagnosed with hypertension. High blood pressure significantly increases the risk of suffering a heart attack or stroke. For the majority of individuals with hypertension there is no single underlying cause, although in a small group of individuals there is a specific condition that causes blood pressure to rise. Conn’s syndrome – the most prevalent curable cause of hypertension – is one of these conditions.
Although diagnosing Conn’s syndrome is complex, accurate diagnosis generally results in successful treatment. Conn’s syndrome is caused by a benign tumor called adenoma (roughly the size of a 5p coin) in one of the adrenal glands which lie near to the kidneys. The tumor causes a vital blood pressure regulating hormone called aldosterone to over produce. Conn’s syndrome can be treated either by using a medication to block the effects of aldosterone or by surgically removing an affected gland.
The novel test, examined in 44 individuals at Addenbrookes hospital in Cambridge, scans the abdomen using ‘positron emission tomography with x-ray computer tomography’ also known as PET-CT. PET-CT is frequently used to diagnose cancer. The team developed a special radioactive tracer called 11C-metomidate, which highlights culprit adenomas in the scan. The test takes approximately 45 minutes to complete.
At present, the standard test for Conn’s syndrome depends on taking blood samples from a vein supplying the adrenal gland to measure the aldosterone level, a complicated and difficult procedure which often fails to confirm diagnosis. However, the team demonstrated that their scan detected adenomas causing high blood pressure in the majority of study participants, making the test a potentially helpful alternative to the current standard test.
Morris Brown, Professor of Clinical Pharmacology at the University of Cambridge, who led the investigation, explained:
“We were excited to see our technique work so well, and shortcut the delays and discomforts associated with the alternative test. We’re using PET-CT on our patients already, but we also plan a larger study to work out who will benefit the most. The test could be especially important or older patients – we often see growths in the adrenal glands during a routine CT scan. Often these growths are not Conn’s adenomas, but it’s difficult to be sure and they create a lot of anxiety in patients and doctors. In the future PET-CT could be a quick way to reassure a lot of patients without the need for detailed investigations.”
Dr Shannon Amoils, Research Advisor at the BHF, stated:
“Conn’s syndrome is the most common curable cause of high blood pressure. And although it affects only a small fraction of people with hypertension, it’s almost certainly more widespread than we previously thought. There are drugs that can control the high blood pressure caused by Conn’s syndrome, but the only cure is surgery, so making the diagnosis is very important. This new approach, using a PET-CT scan, offers real hope that more people with Conn’s syndrome will be accurately diagnosed in the future.”
Chris Wood, 56, who was diagnosed as having Conn’s syndrome by the novel test, explained:
“When I had blood tests before, the results were never clear. I enrolled in Professor Brown’s study I had the scan, which took less than an hour, and immediately after the scan they showed me the pictures of the lump in my adrenal gland that was causing the problem. Getting the definitive diagnosis is fantastic because it removes all the worry, and because I’m on much much less medication than I have been for 15 years. I feel absolutely great.”
The investigation is published online in the Journal of Clinical Endocrinology and Metabolism. The study was funded primarily by the BHF and the National Institute of Health Research (NIHR), the research funding arm of the NHS.
Written by Grace Rattue