Single dose captopril as a diagnostic test for primary aldosteronism.
Most diagnostic tests for primary aldosteronism use maneuvers to expand the extracellular fluid volume, thereby suppressing the renin-angiotensin system. This results in a decline in plasma aldosterone concentrations in normal subjects and essential hypertension (EH) patients, but not in patients with primary aldosteronism. Captopril blocks angiotensin II synthesis and might be used as a diagnostic test for primary aldosteronism. We have measured plasma aldosterone concentrations 2 h after the administration of 25 mg captopril in 9 normotensive subjects, 10 patients with EH, and 12 patients with primary aldosteronism while they were ingesting an unrestricted diet. The plasma aldosterone concentration decreased to less than 15 ng/dl in all normotensive subjects and in 9 of 10 patients with EH, but remained greater than 15 ng/dl in 4 of 5 patients with idiopathic hyperaldosteronism and in all patients with an aldosterone-producing adenoma. The aldosterone to renin ratio was greater than 50 in 4 of 5 patients with idiopathic hyperaldosteronism and in all adenoma patients, but less than 50 in all normotensive subjects and EH patients. A nomogram comparing the plasma aldosterone concentration with the aldosterone to renin ratio clearly separated primary aldosteronism patients from EH patients.
D000236:Adenoma / Q000097:blood; D000310:Adrenal Gland Neoplasms / Q000097:blood; D000328:Adult; D000368:Aged; D000450:Aldosterone / Q000097:blood; D002216:Captopril; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006929:Hyperaldosteronism / Q000097:blood / Q000175:diagnosis* / Q000209:etiology; D006973:Hypertension / Q000150:complications; D008297:Male; D008875:Middle Aged; D011392:Proline / Q000031:analogs & derivatives*; D012083:Renin / Q000097:blood
D000450:Aldosterone; D011392:Proline; D002216:Captopril; D012083:Renin