title: Urinary tetrahydroaldosterone as a screening method for primary aldosteronism: a comparative study.
abstract: BACKGROUND
  The major aldosterone metabolite 3 alpha,5 beta tetrahydroaldosterone reflects up to 45% of the aldosterone secretion. Its 24-h urinary excretion is likely to provide an accurate index of the daily aldosterone production and to be an indicator for primary aldosteronism (PA).
  
  
  METHODS
  In a prospective study, the validity of tetrahydroaldosterone as a screening test for PA was evaluated in comparison to serum potassium, plasma aldosterone, plasma renin activity, plasma aldosterone/renin activity ratio (PARR), as well as 24-h urinary aldosterone-18-glucuronide and free aldosterone. A total of 111 normotensive individuals, 412 PA patients and 1453 essential hypertensive patients, were studied. The effect of blood sampling technique on potassium level was also investigated.
  
  
  RESULTS
  Tetrahydroaldosterone differentiated PA from essential hypertension with a sensitivity of 96% and a specificity of 95%. The sensitivity was 89% for plasma aldosterone, 87% for free aldosterone, 85% for PARR, 71% for aldosterone-18-glucuronide and 51% for renin activity. Specificities varied between 91% and 85%. The combined use of the parameters plasma aldosterone > or =9.0 ng/dL and PARR > or =25 resulted in a sensitivity of 82% and specificity of 95%. Forearm exercise proved to be a source of erroneous elevations of potassium sufficient to obscure the suspicion of PA.
  
  
  CONCLUSIONS
  The data suggest that tetrahydroaldosterone is the most reliable screening test for PA. Tetrahydroaldosterone determination in combination with aldosterone-18-glucuronide and free aldosterone increases diagnostic specificity for PA. Potassium, renin, plasma aldosterone, and basal PARR are inadequate screening procedures because they are subject to high rates of false-positive and false-negative results.
authors.affiliation: Hypertension and Nephrology Unit, Deutsche Klinik für Diagnostik and Klaus Ketzler Institute, Wiesbaden, Aukammallee, Germany. abdelham@mail.uni-mainz.de
authors.forename: Saleh
authors.initials: S
authors.lastname: Abdelhamid
authors.forename: Roland
authors.initials: R
authors.lastname: Blomer
authors.forename: Gerhard
authors.initials: G
authors.lastname: Hommel
authors.forename: Doris
authors.initials: D
authors.lastname: Haack
authors.forename: Sabina
authors.initials: S
authors.lastname: Lewicka
authors.forename: Peter
authors.initials: P
authors.lastname: Fiegel
authors.forename: Bernd
authors.initials: B
authors.lastname: Krumme
mesh_terms: D000293:Adolescent; D000328:Adult; D000450:Aldosterone / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine*; D005260:Female; D020719:Glucuronides / Q000652:urine; D006801:Humans; D006929:Hyperaldosteronism / Q000097:blood / Q000175:diagnosis* / Q000378:metabolism* / Q000652:urine; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011188:Potassium / Q000097:blood; D011446:Prospective Studies; D012083:Renin / Q000097:blood; D012680:Sensitivity and Specificity
chemical_list: D020719:Glucuronides; C013282:tetrahydroaldosterone; D000450:Aldosterone; D012083:Renin; D011188:Potassium