HYPERTENSION IN DISGUISE - A TRAP FOR THE UNWARY

A 36-year-old asymptomatic Chinese male with polycystic kidney disease (PKD) developed hypertension 1 year after the diagnosis of PKD. The p atient was treated initially as for hypertension associated with PKD. However, over a 6-year period his hypertension became progressively di fficult to control and he developed severe symptomatic hypokalaemia. S ubsequent investigations confirmed the presence of primary hyperaldost eronism. The initial computed tomographic scans of the adrenals did no t reveal any definite adenomas. The patient subsequently underwent bil ateral adrenal venous sampling, which suggested a left-sided source of aldosterone excess. A repeat computed tomography of the adrenals with fine cuts revealed a 6-mm diameter adenoma of the left adrenal gland. He underwent an uncomplicated left adrenalectomy, All antihypertensiv e and potassium supplements were stopped on the 5th postoperative day. Two and half years after the adrenalectomy he remains normotensive an d normokalaemic without any medication. The case illustrates the impor tance of measuring serum potassium before initiation of any therapy an d the need to consider secondary causes even if a primary association is known. It also reinforces the fact that when hypertension becomes d ifficult to control, a secondary cause has to be searched actively. Th e association between primary aldosteronism and renal cysts has been h ighlighted only recently. The association of polycystic kidneys and pr imary aldosteronism has been reported in the literature only once prev iously.