title: Effects of circadian rhythms, posture, and medication on renin-aldosterone interrelations in essential hypertensives.
abstract: BACKGROUND
  The aldosterone-to-renin ratio (ARR) is frequently used to screen primary hyperaldosteronism. This study, part of a clinical trial, was designed to measure the influence of circadian rhythms, antihypertensive drugs, and body posture on plasma renin, on aldosterone, and on their interrelation.
  
  
  METHODS
  In a prospective, randomized, open-label, parallel-designed protocol, 57 essential hypertensives (41 men, 16 women) were randomized to a morning dose of telmisartan (80 mg), ramipril (10 mg), or amlodipine (10 mg) for 8 weeks. At baseline and after 8 weeks of therapy, blood pressure (BP), plasma renin (in nanograms per liter), and plasma aldosterone (in picomoles per liter) concentrations were assessed in the supine position every 4 h for 24 h and after 10 min of standing at 9 am.
  
  
  RESULTS
  There was no significant association between renin, aldosterone, the ARR and demographic factors, or BP. Circadian variations of plasma renin and aldosterone were clearly present. Aldosterone variations were of greater relative amplitude with earlier-occurring peaks than renin. The ARR exhibited statistically and clinically significant circadian variations with the low and peak values averaging 55.9 +/- 32.3 and 161.84 +/- 85.4 pmol/L/ng/dL, respectively. Telmisartan, ramipril, and amlodipine significantly decreased the ARR. Telmisartan had the greatest influence on the ARR. Posture had a clinically significant but statistically nonsignificant effect on the ARR.
  
  
  CONCLUSIONS
  Renin, aldosterone, and their interrelation are influenced by circadian rhythms, telmisartan, ramipril, and amlodipine in patients with essential hypertension. Telmisartan has a greater impact on these parameters than ramipril and amlodipine. Measurement of the ARR in treated hypertensive patients should take these influences into account.
authors.affiliation: Institut de Recherches Cliniques de Montréal (IRCM), Canada. lamarrm@ircm.qc.ca
authors.forename: Maxime
authors.initials: M
authors.lastname: Lamarre-Cliche
authors.forename: Jacques
authors.initials: J
authors.lastname: de Champlain
authors.forename: Yves
authors.initials: Y
authors.lastname: Lacourcière
authors.forename: Luc
authors.initials: L
authors.lastname: Poirier
authors.forename: Maria
authors.initials: M
authors.lastname: Karas
authors.forename: Pierre
authors.initials: P
authors.lastname: Larochelle
mesh_terms: D000328:Adult; D000368:Aged; D000450:Aldosterone / Q000097:blood*; D017311:Amlodipine / Q000627:therapeutic use; D047228:Angiotensin II Type 1 Receptor Blockers / Q000627:therapeutic use; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001562:Benzimidazoles / Q000627:therapeutic use; D001565:Benzoates / Q000627:therapeutic use; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D002940:Circadian Rhythm / Q000187:drug effects; D005260:Female; D006801:Humans; D006929:Hyperaldosteronism / Q000175:diagnosis / Q000209:etiology; D006973:Hypertension / Q000097:blood* / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011187:Posture; D011446:Prospective Studies; D017257:Ramipril / Q000627:therapeutic use; D012016:Reference Values; D012083:Renin / Q000097:blood* / Q000187:drug effects; D012084:Renin-Angiotensin System / Q000187:drug effects; D000077333:Telmisartan; D016896:Treatment Outcome
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D001562:Benzimidazoles; D001565:Benzoates; D002121:Calcium Channel Blockers; D017311:Amlodipine; D000450:Aldosterone; D012083:Renin; D017257:Ramipril; D000077333:Telmisartan