title: P-wave dispersion in endogenous and exogenous subclinical hyperthyroidism.
abstract: BACKGROUND
  The aim of this study was to measure maximum P wave duration (Pmax) and P wave dispersion (PWD), which can be indicators for the risk of paroxysmal atrial fibrillation when increased, and to reveal their relationship with thyroid hormone levels in patients with endogenous and exogenous subclinical hyperthyroidism.
  
  
  METHODS
  Seventy-one patients with sublinical thyrotoxicosis (34 endogenous, 37 exogenous) and 69 healthy individuals were enrolled in the study. Pmax and minimum P wave duration (Pmin) on electrocardiogram recordings were measured and PWD was calculated as Pmax-Pmin.
  
  
  RESULTS
  Pmax (p<0.001) and PWD (p<0.001) values were significantly higher in patients with endogenous subclinical hyperthyroidism compared with the control group. Pmax (p<0.001) and PWD (p<0.001) values were significantly higher in patients with exogenous subclinical thyrotoxicosis compared with the control group. Pmax (p=0.710) and PWD (p=0.127) were not significantly different in patients with endogenous subclinical hyperthyroidism compared with exogenous subclinical hyperthyroid patients. Pmax and PWD negatively associated with TSH in endogenous and exogenous subclinical hyperthyroidism.
  
  
  CONCLUSIONS
  In the present study, we observed that Pmax and PWD were longer in patients with endogenous and exogenous subclinical hyperthyroidism. Lack of a difference in Pmax and PWD between patients with endogenous and exogenous subclinical hyperthyroidism seems to support the idea that hormone levels rather than the etiology of thyrotoxicosis affect the heart.
authors.affiliation: Department of Endocrinology and Metabolism, School of Medicine, Mersin University, Mersin, Turkey. ramazangen@gmail.com
authors.forename: R
authors.initials: R
authors.lastname: Gen
authors.forename: E
authors.initials: E
authors.lastname: Akbay
authors.forename: A
authors.initials: A
authors.lastname: Camsari
authors.forename: T
authors.initials: T
authors.lastname: Ozcan
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000503:physiopathology; D000236:Adenoma / Q000503:physiopathology; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000209:etiology; D002291:Carcinoma, Papillary / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006044:Goiter, Nodular / Q000503:physiopathology; D006111:Graves Disease / Q000503:physiopathology; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications* / Q000503:physiopathology*; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000503:physiopathology; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine