A new non-invasive type of CT scan has been shown to light up tiny nodules in a hormone gland and cure high blood pressure by their removal. The nodules are discovered in one in 20 people with high blood pressure.
Doctors at Queen Mary University of London and Barts Hospital, and Cambridge University Hospital have led the study which solves a 60-year problem of how to detect the hormone producing nodules without a difficult catheter study that is available in only a handful of hospitals, and often fails. The research also found that, when combined with a urine test, the scan detects a group of patients who come off all their blood pressure medicines after treatment.
The findings were published in Nature Medicine.
A total of 128 people participated in the study of the new scan after doctors found that their hypertension was caused by a steroid hormone, aldosterone. The scan found that in two-thirds of patients with elevated aldosterone secretion, this was coming from a benign nodule in just one of the adrenal glands, which can then be safely removed.
The scan uses a very short-acting dose of metomidate, a radioactive dye that sticks only to the aldosterone-producing nodule. The scan was as accurate as the old catheter test, but quick, painless and technically successful in every patient.
Until now, the catheter test has been unable to predict which patients would be completely cured of hypertension by surgical removal of the gland. By contrast, the combination of a “hot nodule” on the scan and urine steroid test detected 18 of the 24 patients who achieved a normal blood pressure off all of their drugs.
Professor Morris Brown, co-senior author of the study and professor of Endocrine Hypertension at Queen Mary University, said: “These aldosterone-producing nodules are very small and easily overlooked on a regular CT scan. When they glow for a few minutes after our injection, they are revealed as the obvious cause of hypertension, which can often then be cured. Until now, 99% are never diagnosed because of the difficulty and unavailability of tests. Hopefully this is about to change.”
In most people with high blood pressure, the cause is unknown, and the condition requires life-long treatment by drugs. Previous research by the group at Queen Mary University discovered that in 5%-10% of people with hypertension the cause is a gene mutation in the adrenal glands, resulting in excessive amounts of the steroid hormone, aldosterone, being produced.
Aldosterone causes salt to be retained in the body, driving up the blood pressure. Patients with excessive aldosterone levels in the blood are resistant to treatment with the commonly used drugs for hypertension, and at increased risk of heart attacks and strokes.
Study details
Metomidate PET-CT versus adrenal vein sampling for diagnosing surgically curable primary aldosteronism: a prospective, within-patient trial
Xilin Wu, Russell Senanayake, Emily Goodchild, Morris Brown et al.
Published in Nature Medicine on 16 January 2023
Abstract
Primary aldosteronism (PA) due to a unilateral aldosterone-producing adenoma is a common cause of hypertension. This can be cured, or greatly improved, by adrenal surgery. However, the invasive nature of the standard pre-surgical investigation contributes to fewer than 1% of patients with PA being offered the chance of a cure. The primary objective of our prospective study of 143 patients with PA (NCT02945904) was to compare the accuracy of a non-invasive test, [11C]metomidate positron emission tomography computed tomography (MTO) scanning, with adrenal vein sampling (AVS) in predicting the biochemical remission of PA and the resolution of hypertension after surgery. A total of 128 patients reached 6- to 9-month follow-up, with 78 (61%) treated surgically and 50 (39%) managed medically. Of the 78 patients receiving surgery, 77 achieved one or more PA surgical outcome criterion for success. The accuracies of MTO at predicting biochemical and clinical success following adrenalectomy were, respectively, 72.7 and 65.4%. For AVS, the accuracies were 63.6 and 61.5%. MTO was not significantly superior, but the differences of 9.1% (95% confidence interval = −6.5 to 24.1%) and 3.8% (95% confidence interval = −11.9 to 9.4) lay within the pre-specified −17% margin for non-inferiority (P = 0.00055 and P = 0.0077, respectively). Of 24 serious adverse events, none was considered related to either investigation and 22 were fully resolved. MTO enables non-invasive diagnosis of unilateral PA.
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