Abstract
Background: Worldwide thyroid diseases are one of the most common endocrine disorders. India is also no exception. Thyroid disorders affect all organ systems leading to decreased quality of life and long-term morbidity. The altered levels of thyroid hormone also affect respiratory system. They lead to disorders of respiratory function and disturbances in ventilation.

Aims and Objectives: This study was aimed to explore the respiratory disease pattern in thyroid dysfunction (both hyperthyroid and hypothyroid).

Materials and Methods: After taking clearance from institutional ethical committee, we undertook this case–control observational study. A total of 105 participants were included in the study, 60 euthyroid controls and 45 patients of thyroid disorder (hypothyroid = 30 and hyperthyroid = 15). Convenient sampling technique was used for the study, and simple random sampling technique was used for selecting control groups. Patients were then assessed for thyroid profile. Thyroid-stimulating hormone (TSH), fT3, and fT4 were measured by mini-VIDAS. Once diagnosed with thyroid disorder, these patients were subjected to a battery of pulmonary function test (PFT). We measured the PFT parameters of both cases and controls by SPIRODOC (Spiro PRO6.6 spirometry standard mode, version no. A23-OW-06145). Differences between the study group and controls were examined using SPSS version 19.0. The statistical analysis included one-way ANOVA with Tukey’s Honest Significant Difference post hoc test. Pearson’s correlation was calculated among various parameters. P < 0.05 was considered statistically significant with confidence interval of 95%.

Results: The forced expiratory volume in 1(FEV1)/forced vital capacity (FVC) in euthyroids, hypothyroids, and hyperthyroid was 82.83 ± 1.09, 83.76 ± 2.80, and 83.3 ± 1.77, respectively. FVC in euthyroids was 3.29 ± 0.66, in hypothyroids 2.70 ± 0.52, and in hyperthyroids 2.97 ± 0.48. A restrictive pattern was found in hypothyroid patients whereas we could not find any significant difference in pulmonary functions of hyperthyroid patients when compared with euthyroids. We found a positive linear relation between FEV1 and TSH for both hyperthyroid and hypothyroids (r = 0.54 and r = 0.19, respectively).

Conclusion: Our study shows a restrictive pattern with FEV1/FVC raised in hypothyroid whereas we could not find any statistically significant differences in PFT in hyperthyroid patients.

Key words: Thyroid Function; Pulmonary Function Tests; Hyperthyroid; Hypothyroid