title: Relationship between nocturnal blood pressure and 24-h urinary sodium excretion in a rural population in Korea.
abstract: BACKGROUND
  The relationship between sodium intake and blood pressure (BP) is affected by many factors such as absolute level of sodium intake, salt sensitivity, and the accuracy or the timing of the BP measurement. There is no epidemiologic study using both ambulatory BP monitoring (ABPM) and 24-h urine sample in a middle-aged general population.
  
  
  METHODS
  In the rural area, Yeojoo County, Gyunggi Province in South Korea, 218 subjects with age between 30 and 59 years old were measured with ABPM and 24-h urine sample. ABPM device was TM2430, and the 24-h urine sample was collected using the aliquot cup. Metabolic syndrome (MetS) score was calculated by the sum of the number of abnormal criteria other than BP.
  
  
  RESULTS
  For both ABPM and 24-h urine sample, 148 subject data was acceptable for the analysis by the creatinine equation and/or the completeness of collection. Age was 47.4 ± 8.3 years (range 30 to 59 years), and female was 85 (57.4%). In multiple linear regression analysis, sodium intake was not an independent factor for casual BPs and daytime BPs whereas sodium intake was an independent factor for nighttime systolic BP (β = 1.625, p = 0.0026) and nighttime diastolic BP (β = 1.066, p = 0.0017). When compared to the lowest quartiles of sodium intake, daytime diastolic BP and nighttime BPs were in the higher three quartile groups.
  
  
  CONCLUSIONS
  Sodium intake was associated not with casual BPs and daytime BPs but with increased nighttime BPs in the middle-aged general population in Korea.
authors.affiliation: Department of Internal Medicine, Hanyang University College of Medicine, Seoul, South Korea ; Division of Cardiology, Department of Internal Medicine, Hanyang University Hospital, Hanyang University College of Medicine, 222 Wangsimni-ro, Seongdong-gu, Seoul 133-791 South Korea.
authors.forename: Jinho
authors.initials: J
authors.lastname: Shin
authors.affiliation: Department of Internal Medicine, Hanyang University College of Medicine, Seoul, South Korea.
authors.forename: Enshi
authors.initials: E
authors.lastname: Xu
authors.affiliation: Department of Internal Medicine, Hanyang University College of Medicine, Seoul, South Korea.
authors.forename: Young Hyo
authors.initials: YH
authors.lastname: Lim
authors.affiliation: Department of Preventive Medicine, Hanyang University College of Medicine, Seoul, South Korea.
authors.forename: Bo Youl
authors.initials: BY
authors.lastname: Choi
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Sung-Ae General Hospital, Seoul, South Korea.
authors.forename: Bae Keun
authors.initials: BK
authors.lastname: Kim
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Sung-Ae General Hospital, Seoul, South Korea.
authors.forename: Yong Gu
authors.initials: YG
authors.lastname: Lee
authors.affiliation: Department of Preventive Medicine, Hanyang University College of Medicine, Seoul, South Korea.
authors.forename: Mi Kyung
authors.initials: MK
authors.lastname: Kim
authors.affiliation: Institute for World Health Development, Mukogawa Women's University, Hyogo, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Mori
authors.affiliation: Institute for World Health Development, Mukogawa Women's University, Hyogo, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yamori
keywords: Ambulatory; Blood pressure; Blood pressure monitoring; Rural population; Sodium; Urine specimen collection