Endocrine Abstracts

Aim: Lithium bicarbonate is a drug used in the initial treatment of bipolar disorders. Lithium is an element of alcali metal group and besides being a causative agent for goiter and hypothyroidism primarily, it has also some antithyroid effects. Rarely, lithium may cause hyperthyroidism secondary to thyroiditis or probably autoimmune mechanisms. The association between lithium and thyroid cancer is very little known subject. In this case series, we presented differentiated thyroid cancer in five patients using lithium for the treatment of bipolar affective disorder

Cases: Three of patients were female and two were male. Three patients had hypothyroidism and were using levothyroxine and two patients were euthyroid. There was a solitary thyroid nodule in two, while multiple nodules were present in others. Preoperatively, thyroid fine needle aspiration biopsy was performed in all patients and cytological results were suspicious for malignancy in three, atypical cells in one and atypia of undetermined significance in one subject. Histopathologically, one patient had minimal invasive follicular carcinoma, two had papillary thyroid carcinoma, and two had concomitant papillary thyroid carcinoma and papillary thyroid microcarcinoma. All patients were given radioactive iodine ablation treatment postoperatively.

Conclusion: Thyroid dysfunctions can be observed in patients using lithium due to various mechanisms. Among these, thyroid cancers are the least known and patients with nodular goiter on lithium therapy should be evaluated carefully for the risk of development of thyroid cancer.