title: The relationship between serum sex steroid levels and heart rate variability parameters in males and the effect of age.
abstract: OBJECTIVE
  We evaluated the relationships between sex steroid levels and heart rate variability (HRV) parameters.
  
  
  METHODS
  The study included 114 male subjects (mean age 46.6±11.3 years) presenting to our department for cardiologic evaluation. Hormonal analysis included serum levels of luteinizing hormone, prolactin, total testosterone (TT), free testosterone, estradiol (E2), and dehydroepiandrosterone sulfate (DHEA-S). Parameters of HRV were derived from 24-hour Holter monitoring. The associations between serum sex steroid levels and HRV parameters were investigated in three age groups (20-39 years; 40-59 years; >60 years).
  
  
  RESULTS
  All the participants had normal biochemical results. The three age groups were similar in terms of anthropometric measurements. Among sex steroids analyzed, only serum DHEA-S level was significantly different among the groups (p=0.026), showing a decreasing trend with age. In the evaluation of HRV, all parasympathetic activities decreased (for HFn, pNN50, and rMSDD: p=0.001, p=0.000, and p=0.000, respectively), while only LF/HF among sympathetic activities increased (p=0.000) with age. Partial correlation analysis with control of age and waist circumference showed that TT and DHEA-S were positively correlated with HFn (parasympathetic parameter), and were in negative correlation with LF/HF24 hours and global sympathetic index (GSI) (sympathetic parameters). Serum E2 level was negatively correlated with the parasympathetic parameter of rMSSD, and positively correlated with LF/HF24 hours and GSI. Among serum sex steroids, DHEA-S was the most correlated parameter with autonomic functions.
  
  
  CONCLUSIONS
  Our results showed positive correlations between androgens and parasympathetic activity and between estradiol and sympathetic activity in men, independent from anthropometric factors.
authors.affiliation: Department of Cardiology, Medicine Faculty of Kırıkkale University, Kırıkkale, Turkey. mtolgadogru@gmail.com
authors.forename: M Tolga
authors.initials: MT
authors.lastname: Doğru
authors.forename: M Murad
authors.initials: MM
authors.lastname: Başar
authors.forename: Ercan
authors.initials: E
authors.lastname: Yuvanç
authors.forename: Vedat
authors.initials: V
authors.lastname: Simşek
authors.forename: Omer
authors.initials: O
authors.lastname: Sahin
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D000728:Androgens / Q000097:blood; D001341:Autonomic Nervous System / Q000502:physiology*; D015716:Electrocardiography, Ambulatory; D004958:Estradiol / Q000097:blood; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010275:Parasympathetic Nervous System / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology; D055815:Young Adult
chemical_list: D000728:Androgens; D012739:Gonadal Steroid Hormones; D004958:Estradiol