Chemistry, toxicology & urinalysis
Organ specific
Adrenal
Captopril suppression test
Author: Renu Virk, M.D.
Last author update: 1 February 2010
Last staff update: 2 April 2020
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Captopril suppression test
Cite this page: Virk R. Captopril suppression test. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/adrenalcaptopril.html. Accessed April 24th, 2024.
Definition / general
Indication:
Rationale:
Methodology:
Normal range:
Adverse effects:
- Confirms the diagnosis of primary (hyper) aldosteronism
- One of four tests recommended for screening or confirmation: also oral sodium loading, saline infusion and fludrocortisone suppression (Horm Metab Res 2010;42:406)
- As effective as sodium loading in confirming the diagnosis of primary aldosteronism (Hypertension 2001; 37:1440, Curr Hypertens Rep 2002;4:245)
- Note: Captopril challenge test is used to diagnose renal artery stenosis, differs in that plasma renin (not aldosterone) is measured (Wikipedia - Captopril challenge test)
Rationale:
- Captopril inhibits conversion of angiotensin I to angiotensin II, thereby decreasing aldosterone production in normal individuals
- In patients with primary hyperaldosteronism, the plasma aldosterone levels are NOT suppressed by captopril
Methodology:
- Measure plasma aldosterone levels at baseline and 2 hours after patient takes 25mg of captopril orally
Normal range:
- Plasma aldosterone concentration (PAC) <15 ng/dl (416pmol.L) and PAC to plasma renin activity (PRA) ratio less than 50
Adverse effects:
- Marked hypotension may occur due to captopril intake
- Blood pressure should be monitored regularly
Additional references
