Effects of Short-term and Long-termUse of Lithium on Thyroid Hormones in Nepalese Patients with Bipolar Disorder

Background: Lithium has been used for decades as mood-stabilizing agents in the management of bipolar disorder and other condition with a manic component. However, some studies have also reported varying degrees of thyroid abnormalities associated with lithium therapy and effect of such therapy on thyroid function is unclear in this part of world. Therefore, we aimed to determine the effect of long term use of lithium on thyroidfunctionin the individual with bipolar disorder receiving lithium therapy.

Methods: A total of 75 bipolar disorder patients (24 males, 51 females) who are under lithium therapy and equal number of control were recruited for this study. Diagnosis of bipolar disorder was made by psychiatrist according to ICD-10-DCR guidelines and DSM-IV criteria. Serum fT3, fT4 and TSH were measured by enhanced chemiluminescence immunoassay. Statistical analysis was performed using SPSS 20.0 version.

Results: The prevalence of primary hypothyroidism and subclinical hypothyroidism were found significantly increased in lithium treated group (12% and 17%, respectively) which was further increased with duration of treatment. The mean fT3 and fT4 concentration is low in lithium treated group compared to control group.Butmean TSH level was found significantlyhigher in lithium treated group compared to control (9.67±12.47 vs. 3.41±3.69, p<0.005).

Conclusion: Our findings indicate that use of lithium therapy is associated with higher degree of primary hypothyroidism and subclinical hypothyroidism and female are more susceptible for the thyroid dysfunction associated with lithium therapy.