title: [Relationship between 24-hour urinary sodium and renin-angiotensin-aldosterone system in children with postural tachycardia syndrome].
abstract: OBJECTIVE
  To analyze the relationship between 24 hours urinary sodium and renin-angiotensin-aldosterone system (RAAS) in children with postural tachycardia syndrome (POTS) and to explore low blood volume related pathogenesis of POTS.
  
  
  METHODS
  A total of 39 POTS children who were at the clinic or admitted to the Department of Pediatrics, Peking University First Hospital from June 2012 to February 2013 and 21 healthy children (control group) were enrolled, level of RAAS in plasma, 24-hour urinary sodium and plasma sodium were detected, respectively. Baseline data, levels of RAAS and hemodynamic parameters were compared between POTS and control group, as well as groups with different 24-hour urinary sodium levels of POTS.
  
  
  RESULTS
  The angiotensin II levels of POTS children were significantly higher than that of control group ((105 ± 50) vs (84 ± 28) ng/L, P = 0.041), while no statistical significance was found in plasma renin and aldosterone (P > 0.05). Pearson correlation analysis showed that 24-hour urinary sodium and angiotensin II in children with POTS was negatively correlated (r = -0.536, P < 0.001). Angiotensin II, symptom score, upright heart rate and changes of heart rate were significantly higher in urinary sodium < 124 mmol/24 h group than that in urinary sodium ≥ 124 mmol/24 h group (P < 0.05).
  
  
  CONCLUSIONS
  The regulating function disorder of RAAS may involve in the pathogenesis of POTS and cause sustained low blood volume in patients with POTS.
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Jiawei
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liao
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Junbao
authors.initials: J
authors.lastname: Du
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China; Email: zhangqingyou_73@126.com.
authors.forename: Qingyou
authors.initials: Q
authors.lastname: Zhang
mesh_terms: D000450:Aldosterone; D000804:Angiotensin II; D002648:Child; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D054972:Postural Orthostatic Tachycardia Syndrome; D012083:Renin; D012084:Renin-Angiotensin System; D012964:Sodium
chemical_list: D000804:Angiotensin II; D000450:Aldosterone; D012964:Sodium; D012083:Renin