Abstract

Background:Hypothyroidism is divided in primary, caused by failure of thyroid function and secondary (central) due to the failure of adequate thyroid-stimulating hormone (TSH) secretion from the pituitary gland or thyrotrophin-releasing hormone (TRH) from the hypothalamus. Secondary hypothyroidism can be differentiated in pituitary and hypothalamic by the use of TRH test. In some cases, failure of hormone action in peripheral tissues can be recognized. Primary hypothyroidism may be clinical, where free T4 (FT4) is decreased and TSH is increased or subclinical where FT4 is normal and TSH is increased. In secondary hypothyroidism FT4 is decreased and TSH is normal or decreased. Primary hypothyroidism is most commonly caused by chronic autoimmune thyroiditis, less common causes being radioiodine treatment and thyroidectomy.
Material and Methods:This is a case control study conducted in the Department of General Medicine, NC Medical College & Hospital, Israna, Panipat over a period of 1 year. A total of 120 patients with age between 18 to 60 years were included in the study. The study included 2 groups, group 1 consisted of 60 newly detected hypothyroids and group 2 with 60 controls who were age, sex matched and from similar environment as that of cases. Group 1 hypothyroid patients include both clinical (TSH >5 milli units/L with clinical features of hypothyroidism or low Free thyroxine (FT4)) and subclinical hypothyroidism (TSH>5 with no clinical features of hypothyroidism or normal FT4). Results:In this study, there is no significant difference in age and BMI in cases and controls. TSH was significantly higher while FT3 and FT4 were significantly lower in cases compared to controls. FVC between cases and controls did not show statistical significance, although the mean FVC was found to be lower in cases (1.73) as compared to controls (2.23). Furthermore, observed that there was no significant correlation between TSH or FT4 with FVC, FEV1, and FEV1/FVC as seen in (Table 3 and 4). Conclusion:FT3 level and FT4 level was each significantly associated with fat volume and BMI. Thyroid hormone levels can affect cardiovascular risk through regulation of pericardial fat deposition, in addition to other known mechanisms. In hypothyroidism, there is significant reduction in the dynamic lung functions as compared with controls.