PAC/PRA for primary aldosteronism(PA)

Screening for primary aldosteronism (PA) in individuals with hypertension.

Patients with Hypertension

Measure Aldosterone, Renin, and Potassium

Note: Blood samples should be collected while seated in the morning, ideally without venous stasis. Release the tourniquet after venipuncture and wait at least 5 seconds before withdrawing the blood to avoid misleading increases in potassium levels.

Plasma Renin Activity (PRA), ng/ml/h

Aldosterone

immunoassay

LC-MS/MS

Direct Renin Concentration (DRC), mU/L

Result

False positive result?

Beta-adrenergic blockers or centrally acting alpha2 agonist (e.g., clonidine) that lower renin and increase ARR. (within 2 weeks before testing)

***Consider potential false positive induced by β-adrenergic blockers when aldosterone <15 ng/dL (< 415 pmol/L) by immunoassay

False negative result?

Hypokalemia
Medications that increase renin and decrease ARR
- Strong confounders: MRAs, ENaC inhibitors (within 4 weeks before testing)
- Intermediate confounders: Diuretics (within 4 weeks before testing)
- Weak confounders: ACEIs, ARBs, Dihydropyridine CCB (within 2 weeks before testing)
High pretest probability of PA
Low renin with aldosterone 5-10 ng/dL, 138-277 pmol/L(immunoassay)

Reference

Adler GK, Stowasser M, Correa RR, Khan N, Kline G, McGowan MJ, Mulatero P, Murad MH, Touyz RM, Vaidya A, Williams TA, Yang J, Young WF, Zennaro MC, Brito JP. Primary Aldosteronism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2025 Jul 14:dgaf284. doi: 10.1210/clinem/dgaf284. Epub ahead of print. PMID: 40658480.