Chemistry, toxicology & urinalysis
Organ specific
Adrenal
Fludrocortisone suppression test
Author: Renu Virk, M.D.
Last author update: 1 February 2010
Last staff update: 11 November 2020
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Fludrocortisone suppression test
Table of Contents
Definition / generalCite this page: Virk R. Fludrocortisone suppression test. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/adrenalfludrocortisone.html. Accessed March 22nd, 2023.
Definition / general
Indication:
Rationale:
Procedure:
Normal reference:
Adverse effects:
Clinical, other:
- Confirms the diagnosis of primary (hyper) aldosteronism
- One of four tests recommended for screening or confirmation
- Also:
- Oral sodium loading
- Aaline infusion and captopril suppression (Horm Metab Res 2010;42:406)
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)
