title: Captopril suppression: limitations for confirmation of primary aldosteronism.
abstract: BACKGROUND
  The aldosterone/renin ratio (ARR) is the first line screening test for primary aldosteronism (PA). However, in hypertensive patients with an increased ARR, PA needs to be confirmed by other means.
  
  
  METHODS
  A 25 mg oral captopril test was performed in 16 healthy subjects to obtain reference values for aldosterone and ARR at 120 minutes after the test. Subsequently these data were applied to 46 hypertensive patients screened for PA with an increased ARR.
  
  
  RESULTS
  At 120 minutes after the captopril test ARR decreased in healthy subjects within a narrow range, but remained high in patients with PA and in patients with primary hypertension, especially for those with low renin characteristics. At 120 minutes after captopril, the range of ARR in primary hypertensive patients overlapped in 88% of the cases with the range of the ARR in the PA patients. Sensitivity and specificity of basal ARR and ARR after the captopril test to diagnose PA, calculated as receiver operator characteristics, showed an area under the curve of 0.595 for basal ARR and 0.664 for ARR at 120 minutes after the test.
  
  
  CONCLUSIONS
  The ARR at 120 minutes after the captopril test is only marginally better than basal ARR in diagnosing PA in hypertensive patients screened with an increased ARR. Owing to an overall limited capacity to clearly discriminate PA from primary hypertension, the test could not therefore be recommended for the confirmatory diagnosis of PA.
authors.affiliation: Department of General Practice, Lund University, Sweden. christina.westerdahl@med.lu.se
authors.forename: Christina
authors.initials: C
authors.lastname: Westerdahl
authors.forename: Anders
authors.initials: A
authors.lastname: Bergenfelz
authors.forename: Anders
authors.initials: A
authors.lastname: Isaksson
authors.forename: Stig
authors.initials: S
authors.lastname: Valdemarsson
mesh_terms: D000328:Adult; D000450:Aldosterone / Q000097:blood; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D002216:Captopril / Q000627:therapeutic use*; D005260:Female; D006262:Health; D006801:Humans; D006929:Hyperaldosteronism / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy*; D008297:Male; D012372:ROC Curve; D012083:Renin / Q000097:blood; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D000959:Antihypertensive Agents; D000450:Aldosterone; D002216:Captopril; D012083:Renin