Endocrine Abstracts

A 36-year-old man, presenting to his GP with severe intermittent headaches, was found to have a blood pressure of 210/110 mmHg. He had been diagnosed with familial adenomatous polyposis (FAP) in early childhood, and had had a total colectomy with ileo-rectal anastamosis at the age of 17. Routine surveillance CT imaging the following month revealed an incidental finding of bilateral adrenal masses (right 4×2 cm, left 2.7×2.9 cm).

On assessment in our unit, the patient was found to still be hypertensive at 150/100 mmHg on lisinopril and amlodipine. Serum potassium concentration was normal at 3.8 mmol/l (ref. range 3.5–5.3). Plasma aldosterone was 590 pmol/l, with a plasma renin activity (PRA) of 0.2 pmol/ml per h, giving an aldosterone:PRA ratio of 2950. Saline infusion testing revealed a lack of suppression of aldosterone (plasma levels >280 pmol/l).

Selective adrenal vein sampling (AVS) was undertaken, and indicated dominant secretion of aldosterone from the left adrenal gland, but without complete suppression of secretion from the right. Although large, it was felt that radiologically there were no other suspicious features in the right adrenal mass. With the additional feature of dominant left-sided aldosterone secretion in this case, it was decided that the patient would benefit from laproscopic left adrenalectomy, and he is currently awaiting surgery.

Adrenal gland enlargement is commoner in patients with FAP than the general population, over and above the expected ascertainment bias because these patients undergo frequent abdominal imaging. The majority of adrenal tumours associated with FAP are non-functioning and require no treatment unless they enlarge. However, primary hyperaldosteronism has been reported previously in patients with FAP. Recent research had identified a potential pathophysiological link between adenomatous polyposis coli (APC) gene mutations (which cause FAP), and hyperaldosteronism. This may have implications for the long-term follow-up of patients with FAP.