Objectives: Previous studies based on standard endocrine testing have shown a variable incidence of autonomous cortisol secretion (ACS) or autonomous aldosterone secretion (AAS) in patients with single adrenal adenomas (SAA). We tested whether the use of appropriate controls and modification of standard testing, aiming at eliminating interference from endogenous ACTH, reveals previously undetected subtle ACS and AAS by SAA.
Design: Case control study. Patients We investigated 151 patients with SAA and 72 matched controls with normal adrenal computerized tomography.
Measurements: All participants had arterial blood pressure recorded, and serum cortisol and aldosterone measured before and after intravenous administration of 250 mug of ACTH, and following dexamethasone administration. Eighty-three patients and all the controls had serum aldosterone and renin measured before and after saline infusion, and after a second saline infusion following dexamethasone administration.
Results: Using the mean + 2 SD values obtained from controls after dexamethasone administration and saline infusion following dexamethasone administration, normal cut-off values for cortisol (30.11 nM), aldosterone (67.59 pM), and aldosterone/renin ratio (9.74 pM/mU/l) were developed. Using these cut-off values, the estimated incidence of ACS and AAS in patients with SAA was 56.63% and 24.10%, respectively, whereas 12.05% had autonomous secretion of both cortisol and aldosterone. Systolic and diastolic arterial blood pressure correlated significantly with the aldosterone/renin ratio following AlphaCTH stimulation (P < 0.0002 and P < 0.001, respectively), and after saline infusion following dexamethasone administration (P < 0.003 and P < 0.002, respectively).
Conclusions: By applying new cut-offs, ACS and AAS in patients with a SAA is very common, and aldosterone secretion correlates with arterial blood pressure.