A 51-year-old gentleman was admitted for routine cystoscopy. Intra-operatively, he developed hypertensive emergency requiring admission to Intensive Care Unit. Background consisted of hypertension, type 2 diabetes mellitus, stage 3 chronic kidney disease, anxiety/depression and cannabis use. Prescribed medications were Irbesartan and metformin, albeit with poor compliance. Upon admission, plasma and urinary normetanephrines were elevated at 2347pmol/L (<820, 2.9x upper limit of normal [ULN]) and 11.6umol/day (<3.5, 3.3x ULN) respectively. Plasma metanephrines were normal, 261pmol/L (<447), urinary metanephrines elevated at 2.8umol/day (<1.5). Primary hyperaldosteronism and Cushing’s syndrome were excluded. Angiogram revealed renal artery stenosis (right 70%, left 30%).
CT/MRI head were performed for visual blurring, demonstrating 18mm pituitary tumour, with optic chiasm displacement and right internal carotid encasement. Visual field testing was normal. Anterior pituitary function testing revealed hypogonadotrophic hypogonadism (FSH 4.0IU/L [1.5-13.0], LH 4.2IU/L [1.7-8.6], testosterone 6.6pmol/L [8.0-32.0]), secondary hypothyroidism (TSH 2.66mIU/L [0.4-4.2], fT4 9.3pmol/L [11.0-22.0], fT3 2.8pmol/L [3.0-6.2]), hyperprolactinaemia consistent with stalk effect (680mIU/L [<350]) and likely growth hormone deficiency (GH <0.4mU/L and IGF-1 3.4nmol/L [10-30]). Hypothalamic-pituitary-adrenal axis was sufficient (ACTH 4.1pmol/L [0-12], cortisol 518nmol/L). The patient was discharged on irbesartan and amlodipine pending further work-up for phaeochromocytoma/ paraganglioma (PC/PGL). Plasma and urinary normetanephrines remained persistently elevated (1.5-2x ULN). 68Ga-DOTATATE-PET/CT demonstrated pituitary tumour avidity and no evidence of PC/PGL. Ultrasound neck and MRI pelvis did not detect PC/PGL.
One month later, the patient represented with pituitary apoplexy. Persistent malignant hypertension precluded immediate operative management, with alpha-blockade prior to uneventful transsphenoidal resection. Histopathology demonstrated largely ischaemic tissue; architecture was consistent with pituitary tumour. Subsequent ongoing resistant hypertension prompted performance of a plasma clonidine suppression test.
Evaluation of possible PC/PGL is challenging, requiring careful consideration and interpretation of evolving biochemical and imaging diagnostic modalities (1,2). A plasma clonidine suppression test may assist in identification of false positive elevations in catecholamines (3).