title: Evaluation of autonomic functions in subclinical hypothyroid and hypothyroid patients.
abstract: BACKGROUND
  Autonomic dysfunction may contribute to cardiovascular morbidity in subclinical hypothyroid patients. It is controversial whether the abnormality exists in sympathetic or the parasympathetic function. It is also not known whether the severity of autonomic dysfunction is related to the degree of thyroid deficiency.
  
  
  METHODS
  Prospective case control.
  
  
  METHODS
  Autonomic functions based on heart rate (HR) and blood pressure (BP) responses to various maneuvers were evaluated and scored in twenty two subclinical hypothyroid patients, 30-50 years and compared with twenty hypothyroid patients. Biochemical estimation of TSH, fT3, fT4, TPO antibody was done.
  
  
  RESULTS
  Sympathetic function abnormalities were seen in 82% subclinical hypothyroid patients and 85%hypothyroid patients when one test was abnormal. Parasympathetic dysfunction was also recorded in eight patients in both groups. When two abnormal tests were used as the selection criteria sympathetic function abnormality was observed in about 41% subclinical hypothyroid and 65% hypothyroid patients. There were no intergroup differences in autonomic functions, score and TPO levels. The TSH levels were not related to type or degree of autonomic dysfunction. Systolic BP in both groups and diastolic BP in hypothyroid patients were higher with lower thyroxine levels but the patients were normotensive.
  
  
  CONCLUSIONS
  Autonomic dysfunction of comparable degree was seen in subclinical hypothyroid and hypothyroid patients. Sympathetic function abnormality was more common although decreased parasympathetic function reactivity was also present. These abnormalities were unrelated to TSH levels.
authors.affiliation: Department of Physiology, Maulana Azad Medical College and Lok Nayak Hospital, New Delhi, India.
authors.forename: Aarti S
authors.initials: AS
authors.lastname: Mahajan
authors.forename: Ram
authors.initials: R
authors.lastname: Lal
authors.forename: Dinesh K
authors.initials: DK
authors.lastname: Dhanwal
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Jain
authors.forename: Veena
authors.initials: V
authors.lastname: Chowdhury
keywords: Autonomic dysfunction cardiovascular morbidity; hypertension; subclinical hypothyroidism