In our series, hypertension resolved at follow-up (1 day to 9.7 years) in nearly one third of patients who underwent unilateral laparoscopic adrenalectomy for an aldosterone-producing adenoma. Resolution of hypertension was associated with female gender, fewer pre-operatively prescribed anti-hypertensive medications and lower BMI. Our hypertension cure rate (30%) was similar to other studies in which these patients required no blood pressure medication to maintain a blood pressure ≤120/80 mmHg [22
]. Other studies have noted higher cure rates; however, this was with the utilization of a maximum normal blood pressure of 160/95 mmHg [19
]. Our definition of resolution is in line with current hypertension treatment goals [35
Despite both genders having an average BMI in the overweight or obese range, women weighed significantly less, were almost in the normal weight category (BMI≤25kg/m2
), and 45% of women compared to only 21% of men had complete resolution of their hypertension. In addition females required significantly fewer anti-hypertensive medications pre-operatively, to control their blood pressure. The gender advantage for resolution of hypertension was eliminated in those females who had a BMI in the obese or morbidly obese range. Considering the effect that obesity has on vascular arterial stiffness, vessel sensitivity to pressor substances, and aldosterone secretion, it may be more pertinent than female gender being a prognostic factor for cure of hypertension, as noted by others [28
]. Several studies have noted requiring two or fewer blood pressure medications for blood pressure management, as another predictor of hypertension outcome [28
]. Our results agree with this, as all of the CURE group were on ≤ 2 medications pre-operatively, compared to only 7% of the HTN group, and suggest that females are more responsive to lower doses of medications, and have more readily controlled blood pressure. In addition, females appear to be more responsive and have more readily controllable blood pressure. The amount of adipose tissue in each patient may play a role, as BMI was a prognostic factor between genders and in the CURE group. Weight is a concern, because of the role adipose tissue plays in aldosterone secretion. Obesity is a known contributing factor to increased aldosterone production, as adipose tissue contains factors that function as secretagogues for the hormone [9
]. There is a difference in the activity of the renin-angiotensin system, amongst people of varying weights.
Interestingly, the length of time in which they had been diagnosed with hypertension, was significantly longer in the CURE group, suggesting another etiology for hypertension. The majority of our patients carried a hypertension diagnosis for more than six years. Despite this, 90% of our patients were cured or had improved management of their hypertension with removal of the aldosteronoma. This addresses two issues. First, excess aldosterone makes managing high blood pressure more difficult, and hence, early therapy with a mineralocorticoid receptor antagonist in APA patients and those with resistant hypertension may prove beneficial for blood pressure control, as well as limit end organ damage, as adrenalectomy has been shown to reverse the myocardial changes inflicted by aldosterone [16
]. Secondly, the lack of complete resolution of hypertension suggests another etiology for hypertension. APA with concomitant idiopathic hyperaldosteronism or essential hypertension has been suggested, with the majority of cases being secondary to essential hypertension [36
The majority (70%) of our patients experienced more manageable blood pressure with the pre-operative administration of the mineralocorticoid receptor antagonist, spironolactone, as well as, after tumor resection. Hypokalemia was resolved, and blood pressure more easily controlled. This may be a result of decreased cardiac, vascular and cerebral mineralocorticoid receptor activation. In addition, despite 66% of patients requiring at least six months for a reduction in the number of anti-hypertensive medications, the majority were able to decrease the dose by one-half, within the immediate (<1 month) period. More than likely, our patients have some component of essential hypertension, secondary to the risks factors present (alcohol and tobacco use and obesity). This suggests that in addition to APA resection, lifestyle interventions, including exercising, maintaining an ideal body weight, smoking cessation and minimal alcohol use, are pertinent to the normalization of blood pressure.
In evaluating tumor characteristics, only a minority of our patients had microadenomas (<7mm), which have been reported to secrete higher amounts of aldosterone [37
]. There was no difference in size between genders, even though females on average had tumors <20 mm. The CURE group presented with significantly smaller tumors than the HTN group; however, when further evaluating the HTN group, the improved subgroup had tumors comparable in size to the CURE group. In addition, we examined the histopathology of our patients’ adrenal glands and tumors. Only one patient had evidence of zona glomerulosa and zona fasciculata hyperplasia and/or nodules, end organ changes evident of the lasting effects of hyperaldosteronism. Again, this suggests the presence of essential hypertension.
Our study has few limitations. First, it is a retrospective review on a prospective database. Due to the rare incidence of aldosteronomas, a prospective study would be difficult, due to the time factor. The small number of patients is comparable to other studies [16
]. Despite the length of our study, it was difficult to obtain long term (>2 years) follow up data on some patients. We also excluded the analysis of biochemical and laboratory data, between the groups. Lastly, the small number of patients does not allow more than two subgroups; therefore, conclusions are limited to cure and persistent hypertension, and gender differences.