Comparison of confirmatory tests for the diagnosis of primary aldosteronism

J Clin Endocrinol Metab. 2006 Jul;91(7):2618-23. doi: 10.1210/jc.2006-0078. Epub 2006 May 2.


Context: Primary aldosteronism (PA) is the most frequent form of secondary hypertension, accounting for up to 5-10% of all hypertensive patients, and the diagnosis of PA can present an important challenge for the clinician. After a positive screening test, the diagnosis is confirmed by a suppression test, often an iv saline load test (SLT) or a fludrocortisone suppression test (FST). The FST is considered by many to be the most reliable but is more complex and expensive.

Objective and design: Our objective was to compare the specificity of SLT with FST for the diagnosis of PA.

Patients and setting: The study included 100 hypertensive patients referred to hypertension units with suspected PA after the screening test.

Intervention: All patients underwent FST and SLT.

Main outcome measures: We assessed plasma aldosterone concentrations (PAC) before and after FST and SLT.

Results: After iv SLT, 10.4% of the PA patients were negative and 16.1% of patients with essential hypertension were positive after SLT; that is, a correct diagnosis with SLT was obtained in 88% of patients compared with FST. PAC after SLT and PAC after FST were highly correlated (P < 0.0001). Receiver operator characteristic curve analysis demonstrated that the best cutoff for PAC after SLT was 5 ng/dl. Patients with aldosterone-producing adenoma displayed a smaller reduction of PAC compared with patients with bilateral adrenal hyperplasia; a PAC after SLT greater than 6 ng/dl identified all patients eventually diagnosed as having aldosterone-producing adenoma.

Conclusions: This study demonstrates that the iv SLT is a reasonably good alternative to the more expensive and complex FST for the diagnosis of PA after a positive screening test.

Publication types

  • Comparative Study

MeSH terms

  • Adenoma / diagnosis
  • Adenoma / metabolism
  • Adrenal Gland Neoplasms / diagnosis
  • Adrenal Gland Neoplasms / metabolism
  • Adrenal Glands / pathology
  • Adult
  • Aldosterone / biosynthesis
  • Aldosterone / blood
  • Fludrocortisone*
  • Humans
  • Hyperaldosteronism / complications
  • Hyperaldosteronism / diagnosis*
  • Hyperplasia
  • Hypertension / etiology
  • Middle Aged
  • ROC Curve
  • Sensitivity and Specificity
  • Sodium Chloride* / administration & dosage


  • Sodium Chloride
  • Aldosterone
  • Fludrocortisone