RESPONSE TO UNILATERAL ADRENALECTOMY FOR ALDOSTERONE-PRODUCING ADENOMA - EFFECT OF POTASSIUM LEVELS AND ANGIOTENSIN RESPONSIVENESS

1. Normokalaemic primary aldosteronism (PA) masquerades as 'essential hypertension', and 50% of patients with aldosterone-producing adenoma (APA) are normokalaemic at presentation to this unit. 2. Angiotensin-r esponsive (AII-R) APA is as common as angiotensin-unresponsive (AII-U) APA, and requires adrenal venous sampling for differentiation from bi lateral adrenal hyperplasia (BAH). 3. From 1981 to 1992, 55 patients w ith APA underwent unilateral adrenalectomy and were followed up for at least 12 months postoperatively. Hypertension was cured in 55% and im proved in the remainder. 4. Cure rate was lower (P<0.001) in males (11 /32, 34%) vs females (19/23, 83%), lower (P<0.005) in patients over 45 years of age (13/33, 39%) vs those 45 years or younger (17/22, 77%), lower (P<0.05) in AII-R APA (11/28, 39%) vs AII-U APA (19/27, 70%) and tended to be lower (not significant) in normokalaemic APA (7/17, 41%) vs hypokalaemic APA (23/38, 61%). 5. A higher proportion (P<0.001) of AII-R APA patients were males (23/28, 82%) vs AII-U APA (9/27, 33%), and a higher proportion were from the older age group (AII-R APA 20/28 , 71% vs AII-U APA 13/27, 48%; P<0.05). Females with AII-U APA who wer e hypokalaemic had a very high cure rate (16/17, 94%). 6. Since unilat eral adrenalectomy cures or improves blood pressure in normokalaemic a nd AII-R as well as in hypokalaemic and AII-U patients, all hypertensi ves should be screened for PA, and AII-R APA differentiated from BAH i n proven PA.