Abstract
Background: Hypothyroidism is a common endocrine disorder in our country with a prevalence of 11%, voice is multidimensional and its production involves a complex arrangement between various organs such as oral and nasal cavity, pharynx, larynx, respiratory muscles, and entire respiratory tract, all of which function in a synchronized way on receiving central command from the brain. Reduced thyroid levels lead to altered voice production and voice quality. Hoarseness of voice that is observed in hypothyroidism is usually overshadowed by a plethora of other complaints.

Aims and Objectives: The aim of the study was to profile and document the various voice changes in subjects with hypothyroidism using a comprehensive voice protocol.

Materials and Methods: This cross-sectional study included 50 subjects with hypothyroidism (cases) with age- and sex-matched 50 euthyroid controls. Voice analysis was done on all subjects with hypothyroid on the day of diagnosis after obtaining the institutional ethical clearance. Both the groups underwent aerodynamic measurements, i.e., maximum phonation time (MPT), s/z ratio, acoustic analysis of voice, namely phonation profile, speaking profile, jitter, shimmer, fundamental frequency, and dysphonia severity index (DSI). Perceptual evaluation of voice was done using a grade, roughness, breathiness, asthenia, and strain (GRBAS) scale. Voice disorder outcome profile was used to document the effect of voice problem in day-to-day activities.

Results: Change in voice and fatigue were the major complaint among the hypothyroid cases. MPT and s/z ratio were prolonged in hypothyroid cases when compared to controls. Objective voice analysis revealed a significant change in frequency range, shimmer, and DSI among the cases when compared to controls (P < 0.05). Parameters in GRBAS scale were deviant in hypothyroid cases when compared to controls and were statistically significant (P < 0.05).

Conclusion: The alterations in various parameters of voice observed in hypothyroid patients when compared to euthyroid will help us in better understanding of the pathophysiological changes occurring in hypothyroidism pertaining to voice production.

Key words: Aerodynamic Evaluation; Acoustic Voice Analysis; Dysphonia Severity Index; Hypothyroidism; Perceptual Evaluation of Voice; Voice disorders