London [UK], June 11 : One out of every twenty persons with hypertension has a small benign nodule as the root cause. Aldosterone, a hormone that the nodule generates, regulates the body's salt levels. A gene mutation found in some of these nodules that causes a significant, sporadic overproduction of the hormone is the new finding.
Today's gene variation was found to have a number of issues, which makes it challenging for clinicians to correctly diagnose certain people with hypertension. First, the variation interferes with the ability of cells in the body to communicate with one another and signal when to cease producing aldosterone by affecting a protein called CADM1. Doctors also have a problem with aldosterone's erratic secretion throughout the day, which at its peak contributes to hypertension and salt excess. Unless they take blood tests at multiple times of the day, persons with the gene mutation might avoid detection due to this variability.
The researchers also learned that unilateral adrenalectomy, or the removal of just one of the two adrenal glands, might treat this particular kind of hypertension. After removal, severe hypertension that had been resistant to several pharmacological treatments vanished, and after numerous years of monitoring later, no further therapy was necessary.
Fewer than 1 per cent of people with hypertension caused by aldosterone are identified because aldosterone is not routinely measured as a possible cause. The researchers are recommending that aldosterone is measured through a 24-hour urine test rather than one-off blood measurements, which will discover more people living with hypertension but going undiagnosed.
The initial patient in this study was detected when doctors noticed fluctuation in his hormone levels during his participation in a clinical trial of treatments for difficult hypertension.
In most people with hypertension, the cause is unknown, and the condition requires life-long treatment by drugs. Previous research by the group at Queen Mary discovered that in 5-10 per cent of people with hypertension the cause is a gene mutation in the adrenal glands, which results in excessive amounts of 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.
Professor Morris Brown, co-senior author of the study and Professor of Endocrine Hypertension at Queen Mary University of London, said: "
"In the 900th anniversary of Barts Hospital, this story illustrates benefits from the virtuous circle of Science and Medicine. Most patients consent to our undertaking non-routine molecular analyses of their surgical samples, from which we discover how their hypertension was caused, and how to cure it in future patients. Because the aldosterone nodules in this study were so small, we are now investigating whether momentary cauterisation of the nodule is an alternative to surgical removal of the whole adrenal gland."
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