Karolinska adopts B2 ratio for aldosteronism diagnosis

A piece of removed adrenal tissue sits under the microscope, its cells marked for CYP11B2, the enzyme that makes aldosterone. At Karolinska University Hospital, pathologists now use the B2 ratio to compare the two largest aldosterone-producing nodules and classify primary aldosteronism in routine care.

The disease is a common but often missed cause of high blood pressure. Excess aldosterone disrupts the body's salt balance and raises blood pressure; for some patients, removing the affected adrenal gland can cure or substantially improve the condition. The difficulty comes when several nodules in the same gland are producing the hormone, making it unclear whether one is driving the disease or production is more widespread.

The technique uses an antibody against CYP11B2 to reveal which cells and nodules are actually making aldosterone. The B2 ratio then turns that tissue pattern into a simple comparison between the two largest positive nodules. That gives pathologists a quantitative measure alongside the visual examination of the sample.

The approach grew out of two studies by Christofer Juhlin's research group. The first appeared in the European Journal of Endocrinology in 2025; the second, by Adam Stenman and colleagues, appeared in Histopathology on August 4, 2026. Together, they associated the measure with disease classification and patient outcomes after surgery.

So what changes for patients? A diagnosis made from the removed gland can be more consistent, and clinicians may have a better indication of who is most likely to benefit from surgery. Karolinska has already implemented the B2 ratio in everyday diagnostics.