In this study, 32 unmedicated patients of unipolar depression were included and blood samples were analysed for T(3), T(4) and TSH. These were compared with age and sex matched controls. Subnormal T(3) and T(4) levels in 90.6% and 9.3% respectively and an increase of TSH levels in 18.7% of the total patients was observed in this study. The patients were classified into mild, moderate and severe grade of depression as per DSM-IV criteria. Of the mild 66.6%, 93.3% of moderate and all of the severe grade depression patients had low T(3) levels.Of the moderately depressed patients 13.3% and 9.0% of severe depression patients had low T(4) levels. TSH was increased than normal in 54.5% of the patients and all these patients were of severe grade. ANOVA with multiple comparison testing shows significant decrease in levels of T(3) (F(2.29) >3.33) and significant increase in TSH levels (F(2.29) >3.33) at 5% level of significance amongst mild, moderate and severe grade of depression patients. This study suggests a subclinical hypothyroidism in most of the patients which could lead to nonresponsiveness to the conventional antidepressant therapy. Therefore, evaluation of thyroid status prior to antidepressant therapy and subsequent thyroid hormone substitution in subclinical hypothyroid patients is suggested.
Keywords: Thyroid hormones; depression.