ACTH Stimulation Maximizes the Accuracy of Peripheral Steroi
ACTH can contribute to aldosterone excess in primary aldosteronism (PA) via increased melanocortin type 2 receptor expression. Dynamic manipulation of the hypothalamic-pituitary-adrenal axis could assist PA subtyping, but a direct comparison of dynamic tests is lacking.

Researchers conducted comprehensive dynamic testing in 80 patients: 40 with aldosterone-producing adenoma (APA) and 40 bilateral PA (BPA). Peripheral plasma was collected from each patient at 6 time-points: morning; midnight; after 1 mg dexamethasone suppression; and 15, 30, and 60 minutes after ACTH stimulation. We quantified 17 steroids by mass spectrometry in response to ACTH variations in all patients, and compared their discriminative power between the two PA subtypes.

-- Patients with APA had higher morning and midnight concentrations of 18-hydroxycortisol, 18-oxocortisol, aldosterone, and 18-hydroxycorticosterone than those with BPA.

-- In response to cosyntropin stimulation, the APA group had larger increments of aldosterone, 18-oxocortisol, 11-deoxycorticosterone, corticosterone, and 11-deoxycortisol.

-- Following dexamethasone suppression, the APA group had larger decrements of aldosterone, 18-hydroxycortisol, and 18-oxocortisol, but their concentrations remained higher than in the BPA group.

-- The highest discriminatory performance between the PA subtypes was achieved using steroids measured 15 minutes post-ACTH stimulation.

Conclusively, steroid differences between APA and BPA are enhanced by dynamic hypothalamic-pituitary-adrenal testing; such non-invasive tests could circumvent the need for adrenal vein sampling in a subset of patients with PA.