Endocrine Abstracts

Background: It is well recognised that the most frequent cause of mineralocorticoid induced hypertension is primary hyperaldosteronism. Excess 11-deoxycorticosterone (11-DOC), which is a precursor molecule for the production of aldosterone, may in rare cases be the cause of the mineralocorticoid induced hypertension in patients with normal or low aldosterone levels.

Case: We describe a 70 year old female patient with a background of treated breast cancer who was referred to the endocrinology team in 2019 by her GP with a two-year history of mild hypokalaemia with hypertension requiring two antihypertensive agents for blood pressure control. Further assessment in the endocrinology clinic revealed low renin and low aldosterone levels, normal overnight dexamethasone suppression test, normal metadrenalines, testosterone and DHEAS levels. She underwent CT adrenal which showed a 1.6×1.9 cm indeterminate right adrenal mass (HU=50). MRI adrenal confirmed the presence of a right adrenal mass with restricted diffusion, described as “not a simple adenoma”. Spironolactone was added to her antihypertensives and a plan for right adrenalectomy was made. Due to the COVID pandemic pressures, her surgery & follow upwas delayed. A repeat CT adrenal in 2021 showed no change in size of the adrenal lesion. The patient was no longer keen to proceed with surgery and preferred a more conservative management approach. At that point, she had her hormonal profile repeated which again revealed low renin with low aldosterone, A post low dose dexamethasone suppression test revealed that the 11 deoxycorticosterone remaining elevated at 12 nmol/l, mildly elevated cortisol at 99 nmol/l, normal androstenedione and normal 17 OHP. A urine steroid profile confirmed a marked increase corticosterone metabolite compared to cortisol metabolites and hence a diagnosis of DOC secreting adrenal adenoma was confirmed. An FDG PET CT showed low uptake with stability in size over two years suggesting the adenoma was non-cancerous. A PET 11C metomidate scan performed at Cambridge hospital confirmed increased activity in the right adrenal adenoma.

Conclusion: 11-DOC is a mineralocorticoid precursor with a weaker effect than aldosterone. While a lesion secreting 11-DOC is rare, It is an important cause to consider in patients with hypertension with suppressed aldosterone and renin levels. Serum 11-DOC level and urine steroid profile are essential to aid diagnosis, but there may also be a role for PET 11C metomidate scan in localisation.