BACKGROUND COPD is a major cause of chronic morbidity and mortality throughout the world, leading to years of suffering and premature death from it or its complications. Thyroid hormone regulates the metabolism of proteins, lipids and carbohydrates, and controls the activity of membrane bound enzymes. Thyroid hormone enhances mitochondrial oxidation, and thus, augments metabolic rate. This effect on metabolic rate is probably responsible for the association between the thyroid hormone and respiratory drive. Severity of airway obstruction, hypoxemia, and systemic inflammation may predispose to subclinical hypothyroidism, overt hypothyroidism and non-thyroid illness syndrome. This study was conducted to evaluate the prevalence of thyroid dysfunction in COPD patients. METHODSThis is a cross-sectional, prevalence study. The study was conducted over the period 2017-2018. The study group consisted of male and female COPD patients diagnosed with spirometry and severity was determined according to GOLD criteria. Patients were enrolled in this study from medicine department OPD/IPD. Patients were screened for thyroid dysfunction. RESULTSOut of 121 patients, thyroid dysfunction was present in 45 patients. 11 were subclinical hypothyroidism, 33 hypothyroidism and 1 hyperthyroidism. The prevalence of thyroid dysfunction was 37.2%. In stage A it was 25.8%, stage B 37.5%, Stage C 46.6% and in stage D 39.3%. Thyroid dysfunction was more in smoker COPD patient. Mean FEV1 was less in COPD patients with thyroid dysfunction. CONCLUSIONSThyroid dysfunction is a common extrapulmonary manifestation in COPD patients. Mean FEV1 was decreasing more in COPD patients with thyroid disorders than euthyroid COPD patients. As the staging increases, thyroid dysfunction increases and affects the quality of life in these patients.