Endocrine Abstracts

Case history: A 38-year-old man was referred with a 12-month history of recurrent bouts of transient hyponatraemia (serum sodium ranging from 115 to 125 mmol/l). Citalopram, which he was taking for depression, was discontinued, but the episodes continued.Initial investigations: Whilst symptomatic, and clinically euvolaemic, his biochemical profile was consistent with a syndrome of inappropriate antidiuresis (SIAD): sodium 124 mmol/l, potassium 4.5 mmol/l...

Although adrenal vein sampling (AVS) remains the gold-standard for distinguishing unilateral and bilateral disease in primary hyperaldosteronism (PHA), it is technically demanding and not always feasible. Metomidate (MTO), a potent inhibitor of CYP11B1 and CYP11B2, can be C11H3-labelled as a PET tracer (11C-MTO), and we have previously shown it to be an alternative to AVS for localising unilateral aldosterone-producing adenomas (APAs) (Burton <...

Background: Endocrine Society guidelines classify macroprolactinomas as ‘resistant’ if there is failure to normalise prolactin, or to achieve radiological tumour shrinkage of >50%, on standard doses of dopamine agonist. In this context, escalation of treatment to maximal tolerable doses and/or referral for surgery is advised. However, we have recently observed several ‘discordant responders’, where tumour shrinkage lags significantly (>6 months) beh...