Fludrocortisone suppression test in normal subjects, in patients with essential hypertension and in patients with various forms of aldosteronism.

The response of urinary diurnal tetrahydroaldosterone (TH-aldo) excretion for fluodrocortisone administration (0.3 mg q.i.d. for 3 days) was studied. In normal subjects (n = 13) and in patients with essential hypertension (n = 8), urinary TH-aldo decreased to 36 per cent (range 19-48) and to 51 per cent (range 33-61) of the control value, respectively. Twenty-four patients with primary aldosteronism were studied. Twenty-two of these showed no significant suppression of urinary TH-aldo in that the excretion of TH-aldo was 79 per cent of the control value or more. Nineteen of these patients were submitted to operation, and an adrenal aldosterone-producing adenoma was disclosed in every single case. Two patients with primary aldosteronism demonstrated a significant suppression of aldosterone production to 62 and 68 per cent, respectively. Adrenal micronodular hyperplasia was verified in one case and suspected in the other. A significant suppression of aldosterone production was observed in 4 of 5 patients with aldosteronism and normal or high plasma renin levels. The combination of low plasma renin and autonomy of aldosterone production offers a high degree of certainty for the presence of an aldosterone-producing adenoma.