The effect of including other psychotropic medications into a long-term bipolar disorder lithium treatment on thyroid function

Abstract

Background/Aims. Long-term bipolar disorder (BD) treatment with lithium exerts a significant effect on thyroid structure and function. Compared with BD patients who do not take lithium, patients treated with lithium have higher concentrations of thyroid-stimulating hormone (TSH) and free thyroxine (FT4), lower concentrations of free triiodothyronine (FT3), higher thyroid volume and higher occurrence of goitre. The aim of the study was to compare thyroid structure and function in relation to the inclusion of other mood stabilisers and antidepressants into a lithium treatment. Method. The studied group consisted of eighty BD patients (27 male, 53 female) aged 24–85 years, receiving a prophylactic lithium treatment for the average of 19 ± 9 years. Fifteen patients underwent lithium monotherapy; in 17, lithium was administered concurrently with carbamazepine; in 17, concurrently with quetiapine; and in 11, concurrently with valproate. In 20 subjects, lithium was administered concurrently with antidepressants. Results. In comparison with patients on lithium monotherapy, in patients who took lithium and antidepressant drugs, the concentrations of TSH were significantly higher, while in patients who took lithium and carbamazepine the concentrations of FT4 were lower. The concentrations of thyroid peroxidase antibodies (TPOAb) were significantly higher in patients who took lithium concurrently with antidepressants and concurrently with valproate. The highest frequency of goitre (70%) was observed in patients who took lithium concurrently with antidepressants. Conclusions. The obtained results may suggest a significant effect of including other mood stabilisers and antidepressants into a long-term lithium treatment on thyroid structure and function. A limitation of the study is the small size of the groups.