Adrenal related
Fludrocortisone suppression test

Author: Renu Virk, M.D. (see Authors page)

Revised: 26 January 2016, last major update February 2010

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Fludrocortisone suppression test
Cite this page: Fludrocortisone suppression test. website. Accessed October 28th, 2016.
Definition / General
  • Confirms the diagnosis of primary (hyper) aldosteronism
  • One of four tests recommended for screening or confirmation
  • Also:

  • Fludrocortisone suppresses aldosterone production in normal subjects (molecule is structurally similar to cortisone, Wikipedia - Fludrocortisone), but not in patients with primary aldosteronism

  • Correct hypokalemia if patient is hypokalemic before administering this test
  • Give fludrocortisone 0.2 mg twice daily with 500 mg NaCl supplementation for 3 days (Scand J Clin Lab Invest 2009;69:234)
  • Measure urine aldosterone excretion on the third day

Normal reference:
  • Levels should be < 10 g/d (28 nmol/d) in normal subjects
  • Normal suppression excludes primary hyperaldosteronism

Adverse effects:
  • May precipitate severe hypokalemia
  • Serum potassium should be monitored regularly during the test
  • Due to sodium loading, this test should not be used in the elderly and in patients with severe hypertension
  • Test should be used with care and is not a first line screening test

Clinical, other:
  • Intravenous saline load test is a reasonably good alternative to this more expensive and complex test to diagnose primary aldosteronism after a positive screening test (J Clin Endocrinol Metab 2006;91:2618)