Conn's syndrome due to adrenocortical adenoma--a rare but rewarding cause of curable hypertension.

Objective. To determine the characteristics of an aldosterone-producing adenoma (APA) as a cause of hypertension, its mode of presentation and investigation, as well as the outcome of surgical removal. Design. Retrospective survey with follow-up. Setting. Groote Schuur Hospital, Cape Town. Patients. 18 patients who had an APA removed between 1975 and 1993. Outcome measures. Clinical and biochemical features, morbidity and mortality rates associated with adrenalectomy, and the degree of amelioration of hypertension. Results. Eighteen of 41 patients with primary hyperaldosteronism had an APA. Features of symptomatic hypokalaemia (muscular weakness 9, fatigue 7) were present for a mean of 60 (9 - 240) months. The mean systolic arterial pressure was 153 (117 - 200) mmHg. The mean potassium level was 2,2 mmol/l and the mean aldosterone level 1 639 (147 - 5 153) pmol/l, which, paradoxically, fell on ambulation in 12 patients. All renin levels were suppressed in the supine (mean 0,1 ± 0,1 (0 - 0,6) ng/ml/h) and ambulatory positions (mean 0,4 ± 0,5 (0 - 1,8) ng/ml/h). Each of 17 tomographic and 6 iodocholesterol scans correctly identified the lesion. There was no surgical mortality, and all patients became normokalaemic. At 1 month or at the time of discharge, 12 (66%) patients were normotensive, 7 without medication. Age, length of history, severity of hypertension and evidence of target organ damage did not predict response to surgery. Conclusions. An APA is a rare cause of hypertension and hypokalaemia, but it is important to identify as surgery may be beneficial in most cases.