Chemistry
Adrenal related
Fludrocortisone suppression test


Topic Completed: 1 February 2010

Revised: 31 December 2018, last major update February 2010

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

PubMed Search: Fludrocortisone suppression test

Renu Virk, M.D.
Page views in 2018: 555
Page views in 2019 to date: 360
Cite this page: Virk R. Fludrocortisone suppression test. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/adrenalfludrocortisone.html. Accessed September 19th, 2019.
Definition / general
Indication:
  • Confirms the diagnosis of primary (hyper) aldosteronism
  • One of four tests recommended for screening or confirmation
  • Also:

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

Procedure:
  • 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)

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