Diagnostic challenges in patients with reninomas and extrarenal renin‐producing tumours

Abstract Renin‐secreting tumours are rare causes of secondary hypertension and hypokalaemia. They are usually surgically curable, hence proper diagnostic work‐up and tumour localisation is essential. In this paper, we present three Swedish patients recently diagnosed with renin secreting tumours, two with reninomas and one with an extrarenal renin‐producing tumour, to illustrate diagnostic challenges. We also discuss the biochemical work‐up, the pros and cons of different imaging techniques (computer tomography [CT], magnetic resonance imaging and [18F]fluorodeoxyglucose‐positron emission tomography‐CT), as well as how renal vein sampling (RVC) may contribute to localisation of the tumour.