SUN-346 - An Interesting Case of Lithium Associated Graves Disease

Introduction :
Lithium associated Graves disease is an extremely rare autoimmune disease that can occur with long term lithium use, typically takes several years, however the time course has shown variability, The etiology remains not sufficiently understood
Here we present an interesting case of Lithium associated Graves within few months only.

Case Presentation:
65 Year old man with past medical history of Hypertension, Dyslipidemia who was admitted to the hospital for extreme fatigue, bilateral leg swelling and diarrhea.
He reported fatigue for the past 3 months , also he reported having frequent watery bowel movements for the past 3-4 days prior to admission, he noticed at the same time that his legs are getting more swollen.
He mentioned that he was newly diagnosed with cluster headache and he saw a neurologist who prescribed him Lithium ,he also reported that since he started using the lithium he started having fatigue and inability to perform his daily tasks as he used to,
He decided to stop using it after 2 months, his symptoms slightly improved however not resolved
Physical exam was only significant for bilateral non pitted legs edema
Pt had blood work done including CMP, CBC, ESR, TSH and CRP, All labs came within normal limits except for TSH was < 0.01, Free T4 and came back 3.3, high normal T3 respectively
Patient had TFTs showed TSH 1.8, FT4 1.2, Endo consulted for abnormal TFTs
Ordered repeat TFTs, TSI, TGs, TRAB and thyroid US
Repeat TFTs: TSH < 0.01, FT4 2.6, TSI < 0.1, TGs wnl, TRAB 16.8
Thyroid US showed: Slight asymmetric enlargement of the right lobe compared to the lt with homogenous echogenicity of the thyroid gland and mild hypervascularity, the hypervascularity is non specific could be nonspecific thyroiditis.
Thyroid uptake and scan showed diffusely increased uptake of radioactive iodine throughout the thyroid gland compatible with Graves disease
Patient was started on methimazole 20 mg bid, Beta Blockers was not started .
Discussion
The most common side effect of lithium use and thyroid dysfunction is goiter and hypothyroidism by inhibiting thyroidal iodine uptake, interfering with iodotyrosine coupling and inhibiting thyroid hormone release
Proposed mechanisms of Lithium associated Graves disease is the pathogenesis of LIG is related to autoimmunity and autoantibody production, increase B cell activity and decreased ratios of suppressors to cytotoxic T cells which demonstrates that Lithium induces thyroid autoimmunity among susceptible individuals.
Conclusion
Although Lithium half life is 24 hours and takes up to 9 days to fully eliminates from the body, but Lithium associated Graves should be put in consideration when hyperthyroid symptoms present newly in patient on Lithium .
The management however is Anti thyroid medications, Radio active iodine for pts who do not obtain long term remission and Thyroid gland removal for refractory cases.

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