Table 3 Suppression tests intended to confirm PA
From: Aldosterone-producing adenoma and other surgically correctable forms of primary aldosteronism
Test | Procedure | Assays | Threshold |
|---|---|---|---|
Oral sodium loading test | Increase sodium intake to >200 mmol/d for 3 d, provide ClK to keep plasma K+ | Urinary aldosterone determined from the morning of d 3 to the morning of d 4 | PA unlikely if urinary aldosterone <10 μg/24 h PA likely if urinary aldosterone >12 μg/24 h |
Saline infusion test | Patient in recumbent position for at least 1 h, 2 liters of 0.9% saline iv over 4 h, starting at 0800-0930 h | Kalemia, aldosterone and cortisol at the beginning and the end of the test | PA unlikely if plasma aldosterone <5 ng/dl PA likely if plasma aldosterone >10 ng/dl |
Fludrocortisone suppression test | 0.1 mg oral fludrocortisone every 6 h for 4 d. Provide slow-release KCl to keep plasma K+ and slow release NaCl to maintain urinary sodium excretion >3 mmol/kg body weight | Kalemia 4 times a day during the 4 days. On day 4 determine plasma cortisol, aldosterone and PRA in seated posture at 1000 h | PA likely if upright plasma aldosterone >6 ng/dl on day 4 at 1000 h |
Captopril challenge test | 25-50 mg captopril orally after sitting for at least 1 hour. Patient in seated position for 1 or 2 hours | Plasma aldosterone, PRA and cortisol before and 1 or 2 hours after captopril | PA likely if plasma aldosterone is not suppressed by captopril |