Differentiating aldosterone-producing adenomas (APA) from bilateral adrenal hyperplasia (BAH) as a cause of Conns syndrome (CS) is crucial for appropriate management. We have prospectively evaluated the relative contributions of PST, adrenal imaging by Computed Tomography (CT) and AVS in the differential diagnosis of CS.
We investigated 25 consecutive patients with CS referred to our unit with an identical protocol. Every patient underwent PST, CT and AVS. A single radiologist, blind to the biochemical data, analysed all CT scans, and a single interventional radiologist performed all AVS. For surgically managed patients, the gold standard for a unilateral APA was confirmation of a typical aldosteronoma on histology and long-term post-operative resolution of renin and aldosterone levels. For non-surgically managed patients, successful bilateral adrenal vein cannulation was the gold standard against which PST and imaging were compared. Patients with a right-sided focal adrenal lesion and unsuccessful right adrenal vein (RAV) cannulation, but in whom a successful LAV sampling showed no local over-secretion, were considered to have bilateral aldosterone production.
Bilateral cannulation was achieved in 13 (52%), the LAV only in 11 (44%) and the RAV only in 1 (4%). PST had a 27% sensitivity and 67% specificity; and CT 73% sensitivity and 67% specificity for the diagnosis of APA, each judged against the above gold standards. If patients had surgery on the basis of imaging alone, 2 of 15 (13%) would have had surgery for BAH diagnosed on AVS, and 3 of 10 (33%) thought to have BAH on CT would not have had potentially curative surgery for unilateral aldosterone production demonstrated by AVS.
AVS is an indispensable tool in the differential diagnosis of CS. This is an ongoing study; further histology and post-operative data will be included in the final analysis.
06 - 07 Nov 2006
Society for Endocrinology