title: Association of urinary sodium/potassium ratio with blood pressure: sex and racial differences.
abstract: OBJECTIVE
  Previous studies reporting an association between high BP and high sodium and low potassium intake or urinary sodium/potassium ratio (U[Na(+)]/[K(+)]) primarily included white men and did not control for cardiovascular risk factors.
  
  
  METHODS
  This cross-sectional study investigated the association of U[Na(+)]/[K(+)] with BP in 3303 participants using robust linear regression.
  
  
  RESULTS
  Mean age was 43±10 years, 56% of participants were women, and 52% were African American. BP was higher in African Americans than in non-African Americans, 131/81±20/11 versus 120/76±16/9 mmHg (P<0.001). Mean U[Na(+)]/[K(+)] was 4.4±3.0 in African Americans and 4.1±2.5 in non-African Americans (P=0.002), with medians (interquartile ranges) of 3.7 (3.2) and 3.6 (2.8). Systolic BP increased by 1.6 mmHg (95% confidence interval, 1.0, 2.2) and diastolic BP by 1.0 mmHg (95% confidence interval, 0.6, 1.4) for each 3-unit increase in U[Na(+)]/[K(+)] (P<0.001 for both). This association remained significant after adjusting for diabetes mellitus, smoking, body mass index, total cholesterol, GFR, and urine albumin/creatinine ratio. There was no interaction between African-American race and U[Na(+)]/[K(+)], but for any given value of U[Na(+)]/[K(+)], both systolic BP and diastolic BP were higher in African Americans than in non-African Americans. The diastolic BP increase was higher in men than in women per 3-unit increase in U[Na(+)]/[K(+)] (1.6 versus 0.9 mmHg, interaction P=0.03).
  
  
  CONCLUSIONS
  Dietary Na(+) excess and K(+) deficiency may play an important role in the pathogenesis of hypertension independent of cardiovascular risk factors. This association may be more pronounced in men than in women.
authors: Renal Section, Medical Service, Veterans Affairs North Texas Health Care System, Dallas, TX 75216-7167, USA. susan.hedayati@utsouthwestern.edu
authors: S Susan
authors: SS
authors: Hedayati
authors: Abu T
authors: AT
authors: Minhajuddin
authors: Adeel
authors: A
authors: Ijaz
authors: Orson W
authors: OW
authors: Moe
authors: Essam F
authors: EF
authors: Elsayed
authors: Robert F
authors: RF
authors: Reilly
authors: Chou-Long
authors: CL
authors: Huang
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000419:Albuminuria / Q000208:ethnology / Q000209:etiology / Q000503:physiopathology / Q000652:urine; D015415:Biomarkers / Q000652:urine; D001794:Blood Pressure; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000208:ethnology / Q000209:etiology* / Q000503:physiopathology / Q000652:urine; D007668:Kidney / Q000503:physiopathology; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011188:Potassium / Q000652:urine*; D044469:Racial Groups / Q000706:statistics & numerical data*; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D012964:Sodium / Q000652:urine*; D013781:Texas / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D012964:Sodium; D011188:Potassium