Decade of Hashimoto thyroiditis Followed by Graves disease

Hashimoto's and Graves diseases represent two types of autoimmune thyroid diseases. The concurrence of the two has been described but is still controversial. Occurrence of Graves disease after a decade of hypothyroidism of Hashimoto’s appears to be very rare. We describe here two cases where patient with at least a decade of hypothyroidism of Hashimoto’s presented with Graves disease.

Case 1:70 year old man with pr hypothyroidism diagnosed 15 years prior, on stable dose of LT4 presented with symptoms of hyperthyroidism. He had suppressed TSH (<0.03) and elevated FT4 (1.78) .His LT4 was stopped but the symptoms persisted. He had tachycardia, thyromegaly, proptosis, lid lag, fine tremors and hyperrefelxia. TSI (>500, nl <122) and TG antibodies (194.2, nl 0-4) were elevated. RAI uptake/scan showed: uptake of 16.1%, with elevated trapping and no salivary gland uptake which is a finding in Graves’ disease. Uptake falsely low due to the iodine in multi vitamins that he was taking. He continues to be off LT4 and his free FT4 and TSH started to normalize.

Case 2: 74 year old lady with pr hypothyroidism diagnosed 22 years ago on armour thyroid with stable TSH presented with palpitations. Her TSH was suppressed (0.01) and armour thyroid was discontinued. TSH remained suppressed and she underwent RAI uptake/scan x2. It showed: uptake of 31.2%(64% on the 2^ndone) and cold nodules in both lobes. She underwent FNA of 3 cold nodules, which were reported as negative for malignancy and consistent with Hashimoto’s thyroiditis. TPO  (>369.1, nl 0.9-9), TSI (673, nl <122) and TG antibodies (59.5, nl 0-4) were elevated .She was started on MMI and remained on it for 2 years until she developed leukopenia and it was stopped. Few weeks later she became hyperthyroid and PTU was started which she stopped after 4 doses. Off PTU she developed atrial fibrillation and pulmonary embolism and got CT scan with IV contrast. She was restarted on PTU. Her thyroid function started to improve and is scheduled for thyroidectomy in March 2013, final pathology report will be available after that.

These two cases illustrate the fact that Graves disease with florid hyperthyroidism can occur in a setting of long standing primary hypothyroidism of Hashimoto’s. Therefore thyroid autoimmunity can definitively be considered a spectrum of one pathogenesis. Clinical management of both extremes of thyroid autoimmunity becomes complex when transitioning from one to the other.