AN ANALYTICAL CROSS SECTIONAL STUDY ON CARDIAC AUTONOMIC FUNCTIONS IN HYPO-THYROID PATIENTS

Abstract

Background: Primary Hypothyroidism is a chronic endocrine disorder of thyroid gland with multifarious etiology 1 having a prevalence of 5 to 15% in India. The prevailing literature reports an increased risk of cardiovascular morbidity in hypothyroid patients and proposes derangements in the autonomic nervous system as an antecedent causative event. The present study was designed to explore these undermined autonomic nervous system derangements posing a risk of subsequent development of cardiovascular problems in hypothyroid patients. Aim and Objective: The objective of the current study was to explore and compare the cardiovascular autonomic functions in hypothyroid patients with age and sex-matched healthy controls. Materials and Methods: The present study was conducted in the Upgraded Department of Physiology, Sawai Man Singh Medical College and Attached Hospitals, Jaipur, enrolling 30 hypothyroid patients of both gender, recruited from the Department of Endocrinology and 30 age & gender-matched healthy controls recruited amongst the attendants and family members accompanying the hypothyroid patients. Prior approval and consent were obtained from the institutional ethics committee and research review board before commencement of the study. For assessing the autonomic functions, parasympathetic function tests namely E:I ratio, 30:15 ratio (lying to standing ratio), and valsalva ratio were resorted to, whereas, tests like blood pressure (BP) response to standing and sustained handgrip were used for the assessment of sympathetic functions. Results: When the subjects were tested for assessment of the sympathetic function, rise in diastolic BP during isometric handgrip exercise came out to be signicantly lower in hypothyroid patients (P < 0.05) in comparison to controls. Similarly, the fall in systolic BP on immediate standing was higher in the hypothyroid group (P < 0.05). On assessing the subjects for parasympathetic functions, E: I ratio (Expiration: Inspiration), 30:15 ratio and Valsalva ratio were found to be signicantly decreased (P < 0.05) in hypothyroid patients in comparison to healthy controls. Conclusion: The deranged autonomic function tests in hypothyroid patients suggest an underlying cardiovascular autonomic dysfunction putting hypothyroid patients at a greater risk of cardiovascular diseases later in life. Due to these prognostic implications, the present study recommends regular and periodic assessment of autonomic functions in hypothyroid patients.