title: Clinical and laboratory indices that enhance the diagnosis of postural tachycardia syndrome.
abstract: OBJECTIVE
  To identify clinical and laboratory indices that improve the diagnosis of the postural tachycardia syndrome (POTS).
  
  
  METHODS
  We assessed associations of orthostatic intolerance by using multivariate regression analysis.
  
  
  METHODS
  We evaluated autonomic symptoms and autonomic function in 30 patients with POTS, 30 patients with mild orthostatic intolerance, and 19 age- and gender-matched control subjects. Indices of parasympathetic and sympathetic functions were analyzed on the basis of (1) autonomic function tests (head-up tilt), (2) oscillations at respiratory and nonrespiratory frequencies (0.01 to 0.09 Hz) in R-R interval and blood pressure (Wigner distribution), and (3) deterministic component (rescaled range analysis).
  
  
  RESULTS
  The four clinical and laboratory indices that independently supported the diagnosis of POTS are as follows: (1) orthostatic heart rate during the first minute of head-up tilt, (2) autonomic deficit (adrenergic autonomic score), (3) loss of spectral powers in R-R interval during head-up tilt at the fifth minute, and (4) severity of orthostatic dizziness, fatigue, palpitations, and shortness of breath.
  
  
  CONCLUSIONS
  Enhancing the sensitivity and specificity of the diagnosis of POTS should be possible by using these four indices. A hyperadrenergic state and distal neuropathy, affecting adrenergic sympathetic cardiovagal fibers, seem to be involved in the pathophysiology of POTS. Certain features suggest brain-stem dysregulation.
authors.affiliation: Department of Neurology, Mayo Clinic Rochester, MN 55905, USA.
authors.forename: V
authors.initials: V
authors.lastname: Novak
authors.forename: P
authors.initials: P
authors.lastname: Novak
authors.forename: T L
authors.initials: TL
authors.lastname: Opfer-Gehrking
authors.forename: P C
authors.initials: PC
authors.lastname: O'Brien
authors.forename: P A
authors.initials: PA
authors.lastname: Low
mesh_terms: D000328:Adult; D001794:Blood Pressure; D016022:Case-Control Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D007024:Hypotension, Orthostatic / Q000150:complications* / Q000503:physiopathology*; D008297:Male; D015999:Multivariate Analysis; D012044:Regression Analysis; D012720:Severity of Illness Index; D013610:Tachycardia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology*; D018667:Tilt-Table Test; D013997:Time Factors; D014630:Vagus Nerve / Q000503:physiopathology