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Clinical chemistry

Adrenal Gland

Fludrocortisone suppression test


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

Revised: 21 September 2012, last major update - February 2010

Copyright: (c) 2002-2012, PathologyOutlines.com, Inc.




● Confirms the diagnosis of primary (hyper) aldosteronism

● One of four tests recommended for screening or confirmation: also oral sodium loading, saline infusion and captopril suppression (Horm Metab Res 2010 Jan 29 [Epub ahead of print])




● Fludrocortisone suppresses aldosterone production in normal subjects (molecule is structurally similar to cortisone, Wikipedia), 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)


Additional references


Leeds General Infirmary & Harrogate General Hospital


End of Clinical Chemistry > Adrenal Gland > Fludrocortisone suppression test



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