Aldosterone-secreting adrenal adenomas are extremely sensitive to ACTH stimulation and, as a result, plasma aldosterone has the same circadian rhythm as plasma cortisol in these patients. Hyperkalaemia can directly stimulate the zona glomerulosa. Conversely, hypokalaemia may inhibit aldosterone synthesis. Thus, in patients with Conn's syndrome, aldosterone secretion may be markedly stimulated by potassium replacement therapy.
