Endocrine Abstracts

A 47-year-old man attending Endocrine services for the management of Cushing’s disease in remission, presented with resistant hypertension which warranted further investigation. He initially presented in 2013 with Cushing’s disease and underwent successful transsphenoidal surgery. Postoperatively he was diagnosed with ACTH deficiency, partial growth hormone deficiency, and diabetes insipidus for which he was prescribed hydrocortisone 10 mg daily and desmotab 0.2 mg nocte. During his outpatient follow-up, he continued to be hypertensive despite remission of disease, and treatment was escalated over the subsequent six years until he eventually required five agents – ramipril 10 mg, amlodipine 10 mg, bisoprolol 10 mg, spironolactone 100 mg, doxazosin 8 mg. At this point, an ambulatory blood pressure monitor recorded daytime average blood pressure of 142/85 mmHg and nighttime average blood pressure of 150/88 mmHg. He had episodes of spontaneous hypokalaemia and symptoms suggestive of obstructive sleep apnoea. Initial investigations ruled out Cushing’s disease recurrence, with cortisol 11 nmol/l post-1 mg overnight dexamethasone suppression test. Additional biochemical work-up revealed elevated aldosterone 877 pmol/l, and a fully suppressed renin <5 mIU/l, with normal potassium 3.9 mmol/l and normal plasma metanephrines, taken whilst off beta-blockers. Aldosterone-renin ratio was 175.4 suggestive of primary hyperaldosteronism. Difficult to control hypertension significantly compromised the interpretability of biochemical workup. Equally, a saline suppression test was not suitable. Cross-sectional imaging revealed a 1.2 cm left adrenal nodule with attenuation of 35 Hounsfield units and a general decrease in volume of the adrenal glands in keeping with his status of ACTH deficiency. Confirmatory testing was required and following multidisciplinary team discussion, he proceeded to adrenal vein sampling. On the first attempt at adrenal vein sampling, there was a failure to cannulate the right adrenal vein. Repeat testing was successful and lateralized to the left adrenal gland, with a lateralization index of 39.5 and a contralateral suppression index of 0.71. The patient is listed for robotic left adrenalectomy in early 2024. The key learning points from this case centre around the diagnostic workup of primary hyperaldosteronism including the interpretability of renin and aldosterone concentrations in antihypertensive agent use, and the interpretation of adrenal vein sampling results. It also highlights the importance of considering alternative endocrine diagnoses in patients attending the outpatient clinic.