Abstract
Objective: To elucidate thyroid gland functioning in the manic phase of bipolar disorder type I by thyroid function tests i.e., serum thyroid stimulating hormone (TSH), free thyroxine (FT4) and free triiodothyronine levels (FT3) in patients versus healthy controls (HC).
Methodology: Forty consecutive bipolar disorder (BD) patients with manic episode, index or recurrent diagnosed according to DSM-5 criteria, presenting to the department of psychiatry of a tertiary care teaching hospital of a private medical college were included in this study. In cases, the Young Mania Rating Scale (YMRS) was administered to measure the severity of mania. Fasting serum was taken from both cases and controls and TSH, FT4 and FT3 measured. Cases were compared for TSH, FT3 and FT4, followed by stratification for age, gender, and duration of illness. The tests of significance applied were Chi-square and Student t-test. Data were analyzed by SPSS 24.
Results: Both cases and controls had comparable sociodemographic characteristics. Amongst the cases with mania, the mean serum FT3 levels (360±124 pg/dl) and FT4 levels (0.84±0.52 ng/dl) were higher as compared to controls, but the difference wasn’t statistically significant (p>0.05). Serum TSH in manic cases (0.52±1.89 mIU/L) was significantly lower than that in controls (p≤0.001). There was no significant correlation of FT3, FT4, and TSH with the duration of illness.
Conclusion: Subtle thyroid hormone abnormalities in bipolar disorder suggest a potential pathophysiological role, warranting further investigation.

Key words: Bipolar disorder, free triiodothyronine, free thyroxine, mania, thyroid stimulating hormone.