Endocrine Abstracts

Introduction: Primary aldosteronism is associated with increased prevalence of cardiometabolic complications. The mechanisms are not fully elucidated, but an association with autonomous cortisol secretion could increase vascular and metabolic risk.

Aims: To assess glucocorticoid axis in patients with primary aldosteronism as compared to patients with ACTH-independent Cushing syndrome and control hypertensive patients without gluco or mineralocorticoid excess.

Patients and methods: Twenty two patients (10M/12F, aged 43.9±11.2 years) with primary aldosteronism- PA (14 adrenal tumors, 8 uni/bilateral adrenal hyperplasia), 13 patients (2M/11F, aged 43.8±13.3 years) with ACTH-independent Cushing syndrome and 42 control hypertensive patients (16M/26F, aged 35.8±14.5 years) were retrospectively reviewed. Plasma aldosterone and plasma direct renin were measured by chemiluminescence (method’s sensitivity 2.2 ng/dl for aldosterone and 0.27 ng/dl for renin, respectively); serum cortisol and ACTH were measured by electrochemiluminescence.

Results: BMI, maximum systolic blood pressure, fasting glycaemia and total cholesterol were similar in the three groups. Serum potassium levels in patients with PA (2.6±0.5 mmol/l) were significantly lower than in patients with ACTH independent Cushing syndrome (4.3±0.9 mmol/l, P<0.0001) and in control patients (4.4±0.4 mmol/l, P<0.0001). Midnight (11 p.m.) serum cortisol in PA patients (4.9±3.1 μg/dl) was significantly lower than in patients with ACTH-independent Cushing syndrome (10.4±3 μg/dl, P=0.007), and similar with control patients (3.2±2.7 μg/dl, P=0.17). Median serum 8 a.m. cortisol after 1 mg low-dose dexamethasone suppression test (LDDST) in PA patients (1.34 μg/dl) was significantly lower than in patients with ACTH-independent Cushing syndrome (12.3 μg/dl, P<0.0001), but significantly higher than in control patients (0.84 μg/dl, P=0.001). ACTH levels were similar in PA patients and in control group. One operated patient with PA developed postoperative adrenal insufficiency and required glucocorticoid replacement therapy.

Conclusion: Mild cortisol excess may co-exist in primary aldosteronism patients, reflected by higher cortisol levels after overnight low-dose dexamethasone test.