title: [Clinical value of 24-hour urinary sodium determination in children with postural tachycardia syndrome].
abstract: OBJECTIVE
  To analyze the clinical value of 24-hour urinary sodium determination in children with postural tachycardia syndrome (POTS).
  
  
  METHODS
  Fifty-eight POTS children and 10 healthy children (control group) from Peking University First Hospital during June 2012 to May 2014 were enrolled. Their 24-hour urinary sodium and plasma sodium levels were compared. Correlation analysis was done between 24-hour urinary sodium and symptom scores in children with POTS. All patients were treated with oral rehydration salts. The POTS patients were divided into hyponatriuria group (urinary sodium < 124 mmol/24 h) and hypernatriuria group (urinary sodium ≥ 124 mmol/24 h). Kaplan-Meier curve was used to analyze the effects of different 24-hour urinary sodium levels in children with POTS receiving rehydration salts therapy.
  
  
  RESULTS
  The 24-hour urinary sodium levels of children with POTS were significantly lower than that of control group ((110. 0 ± 45. 8) vs. (221. 3 ± 103. 6) mmol/24 h, t =3. 339, P = 0. 008), while no statistical significance was found in plasma sodium between the two groups ((139. 7 ± 2. 1) vs. (139. 7 ± 2. 3) mmol/L, t = 0. 082, P = 0. 935). Pearson correlation analysis showed that 24-hour urinary sodium and severity of symptoms in children patients were negatively correlated (r = - 0. 654, P < 0. 001) . Urinary sodium < 124 mmol/24 h was used as the cut-off value, there were 43 cases in hyponatriuria group and 15 cases in hypernatriuria group. The symptom scores were significantly higher in hyponatriuria group (10. 2 ± 3. 7 vs. 5. 0 ± 1. 8, P < 0. 001), there was no significant difference in other basic information and hemodynamic data between groups (P > 0. 05). Logistic regression analysis revealed that urine sodium < 124 mmol/24 h was independent risk factor for effectiveness of rehydration salts in POTS patients (OR = 0. 043, 95% CI:0. 004 - 0. 499, P = 0. 012). Kaplan-Meier survival analysis showed the long-term effect of patients receiving oral rehydration salts in hyponatriuria group was significantly better than that in hypernatriuria group (86. 0 % vs. 60. 0%, χ2 = 8. 471, P = 0. 004).
  
  
  CONCLUSIONS
  Twenty-four hours urinary sodium is a good indicaor for guiding children with POTS receiving rehydration salts therapy.
authors.forename: Jiawei
authors.initials: J
authors.lastname: Li
authors.forename: Qingyou
authors.initials: Q
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Liao
authors.forename: Chunyu
authors.initials: C
authors.lastname: Zhang
authors.forename: Junbao
authors.initials: J
authors.lastname: Du
mesh_terms: D016022:Case-Control Studies; D002648:Child; D005440:Fluid Therapy; D006439:Hemodynamics; D006801:Humans; D054972:Postural Orthostatic Tachycardia Syndrome / Q000652:urine*; D015532:Rehydration Solutions; D012492:Salts; D012964:Sodium / Q000652:urine*
chemical_list: D015532:Rehydration Solutions; D012492:Salts; D012964:Sodium