Endocrine Abstracts

Case history: A 26 year-old lady was admitted from clinic with severe hypertension and bilateral papilloedema. Six weeks prior to admission she had undergone resection of a massive right upper quadrant lesion that was felt to be of hepatic origin. Histological analysis of the lesion revealed it to be an adrenal phaeochromocytoma and she was thus referred to the endocrine service. Pre-operative biochemical assessment had not been performed but there was no evidence of any blood pressure abnormality or variation pre- or peri-operatively. Two weeks post-operatively she began to experience episodes of palpitations, sweating and hypertension and had attended the emergency department of her local hospital on a number of occasions and been commenced on doxazosin.

Results and treatment: Review of the surgical pathology confirmed the diagnosis of a phaeochromocytoma with tumour present at the resection margin. Immunohistochemistry for the SDHB protein was negative, suggestive of a germline SDHx mutation. She was admitted to the High Dependency Unit for invasive blood pressure monitoring and commenced on IV labetalol alongside oral phenoxybenzamine given the previous diagnosis and incomplete resection. Urine and plasma metanephrines were subsequently normal. She was hypokalaemic on admission (K 3.2 mmol/l) and given the large size of the original lesion (18 cm), renovascular mediated hypertension was considered. This was confirmed biochemically and hyperreninaemic hyperaldosteronism demonstrated (renin 18.3 nmol/l/h, aldosterone 1,014 pmol/l). Imaging confirmed infarction of the right kidney due to ligation of the renal artery with a DMSA scan confirming only a 5% contribution from the right kidney. Serum creatinine was normal. Her oral anti-hypertensives were rationalised to doxazosin and losartan. This combination was chosen to provide mechanism direct treatment of the current driver of hypertension, whilst providing alpha blockade given the incomplete phaeochromocytoma resection and risk of local recurrence. The results of genetic analysis for germline mutations in phaeochromocytoma-predisposing genes (and particularly SDHx given the negative SDHB immunohistochemistry) are awaited.

Conclusions and points for discussion: This is an unusual and interesting case of acute secondary hyperaldosteronism due to inadvertent surgical ligation of the renal artery. The fact that the original operation was for an undiagnosed phaeochromocytoma, which was incompletely resected, further complicates matters and led to an initial assumption of catecholamine-mediated hypertension. It provides an excellent opportunity to discuss:

• Non-catecholamine-mediated causes of hypertension following phaeochromocytoma surgery

• The mechanism and management of renin-mediated hypertension and particularly whether, in this instance, nephrectomy might play a role