title: Aldosterone-to-renin ratio and the relationship between urinary salt excretion and blood pressure in a community of African ancestry.
abstract: BACKGROUND
  Although aldosterone influences the effect of salt intake on blood pressure (BP), the extent to which this occurs at a population level is uncertain. We therefore aimed to determine, at a community level in a group of African descent, whether in the absence of primary aldosteronism, the relationship between salt intake and BP is modified by circulating aldosterone, and the extent to which this occurs.
  
  
  METHODS
  In 575 participants of African ancestry (age >16 years), we assessed whether aldosterone-to-renin ratio (ARR) is associated with the relationship between urinary sodium (Na(+))-to-potassium (K(+)) ratio (urinary Na(+)/K(+)) (from 24-h urine samples), an index of salt intake, and BP.
  
  
  RESULTS
  With adjustments for confounders, interactions between ARR and urinary Na(+)/K(+) were independently associated with systolic BP (SBP) (P < 0.0001), an effect that was accounted for by interactions between serum aldosterone concentrations and urinary Na(+)/K(+) (P < 0.0001), but not between plasma renin concentrations and urinary Na(+)/K(+) (P = 0.52). The interaction between ARR and urinary Na(+)/K(+) translated into a marked difference in the relationship between urinary Na(+)/K(+) and SBP in participants above compared to below the median for ARR (effect of 1 s.d. increase in urinary Na(+)/K(+) on SBP: ARR > median = 4.2 ± 0.6 mm Hg; ARR < median = 1.2 ± 0.4 mm Hg, P < 0.0001). In addition, participants with urinary Na(+)/K(+) above the median had higher multivariate-adjusted SBP (P < 0.001) only if ARR was also above the median.
  
  
  CONCLUSIONS
  In groups of African descent, in the absence of primary aldosteronism, an increased aldosterone concentration relative to renin modifies a substantial proportion of the relationship between urinary Na(+)/K(+) and BP at a community level.
authors: Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa.
authors: Leon
authors: L
authors: Scott
authors: Angela J
authors: AJ
authors: Woodiwiss
authors: Muzi J
authors: MJ
authors: Maseko
authors: Demetri G A
authors: DG
authors: Veliotes
authors: Olebogeng H I
authors: OH
authors: Majane
authors: Janice
authors: J
authors: Paiker
authors: Pinhas
authors: P
authors: Sareli
authors: Gavin R
authors: GR
authors: Norton
mesh_terms: D000328:Adult; D000450:Aldosterone / Q000097:blood*; D044383:Black People; D001794:Blood Pressure / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000652:urine; D012083:Renin / Q000097:blood*; D012965:Sodium Chloride / Q000652:urine*; D017673:Sodium Chloride, Dietary / Q000494:pharmacology*
chemical_list: D017673:Sodium Chloride, Dietary; D012965:Sodium Chloride; D000450:Aldosterone; D012083:Renin; D011188:Potassium