Table 3.

Interpretations of Biochemical Dynamic Confirmation Results for Primary Aldosteronism

Test	Brief Methodology	Most Conservative Positive Interpretation	More Permissive Positive Interpretation
Oral sodium suppression	• Increase dietary sodium to >200 mmol/d for 3-4 d	Twenty-four–hour urinary aldosterone excretion rate >12–14 μg	Twenty-four–hour urinary aldosterone excretion rate >10 μg
	• Measure 24-h urine sodium, creatinine, and aldosterone excretion rate on day 3 or 4
Supine intravenous saline suppression	• Following 1 h of supine rest, infuse 2 L of normal saline during 4 h	Postinfusion aldosterone level >10 ng/dL	Postinfusion aldosterone level >5 ng/dL
	• Measure PRA and serum aldosterone before and after infusion
Fludrocortisone suppression	• Administer 0.10 mg of fludrocortisone every 6 h for 4 d, while maintaining normal serum potassium and high dietary sodium intake	Seated aldosterone >6 ng/dL with PRA <1.0 ng/mL/h
	• Measure PRA and serum aldosterone while seated on morning of day 4
	• Dexamethasone suppression can also be performed to minimize confounding by ACTH
Captopril challenge	• Administer 25 mg of oral captopril after 1 h of seated posture	• Less than 30% suppression of aldosterone from baseline while PRA remains suppressed (97)	• ARR postcaptopril >20 ng/dL per ng/mL/h
	• Measure PRA, serum aldosterone, and ARR before and 1 h and 2 h after captopril in seated position	alternatively• ARR postcaptopril >30 ng/dL per ng/mL/h (108)

Interpretations are based on the Endocrine Society guidelines (97).

Abbreviation: PRA, plasma renin activity.