The Unusual Late-Onset Graves’ Disease following Hashimoto’s Related Hypothyroidism: A Case Report and Literature Review

Abstract

Background. The shift of Graves’ disease (GD) to Hashimoto’s disease- (HD-) related hypothyroidism is well established. However, the opposite is rare. This is likely to the loss of critical thyroid mass available for stimulation by thyroid hormone receptor stimulating antibody, making this shift unusual. Herein, we report a young lady with a late shift from HD into GD and present a scoping literature review. Case presentation. We report a twenty-five-year-old lady with a sixteen-year-history of Hashimoto’s-related hypothyroidism stable on levothyroxine. While following in the clinic, she started developing thyrotoxic symptoms in the form of anxiety, weight loss, and palpitation. Physical examination was remarkable for mild exophthalmos. The thyroid function test confirmed hyperthyroidism. Levothyroxine-induced hyperthyroidism was initially suspected; however, the symptoms did not improve despite reducing and stopping levothyroxine. Subsequent workup confirmed the diagnosis of GD. Discussion and Conclusion. This case highlights a unique association that has significant diagnostic and management implications. This shift should be considered when hyperthyroidism persists despite reducing or stopping levothyroxine. The diagnosis is made utilizing antibody titers and radioiodine update scan. While the management depends on the disease’s stage and the treating physician preference, antithyroid agents can be used initially. Following up these patients is essential as the shift can be transient.

A case of Hashimoto's thyroiditis following Graves' disease

“…On the contrary, Sukik et al 13 reported a very rare case of Hashimoto's thyroiditis shifting to Graves' disease after sixteen years from the initial diagnosis. Both Graves' disease and Hashimoto's thyroiditis share autoimmunity pathogenesis and the shift from one condition to another is possible 13 . However, the pathogenesis of Hashimoto's thyroiditis following Graves' disease has not been confirmed.…”

“…Hashimoto's thyroiditis manifested 7 to 25 years after the treatment of Graves' disease in three cases and after a few months in one patient. On the contrary, Sukik et al 13 reported a very rare case of Hashimoto's thyroiditis shifting to Graves' disease after sixteen years from the initial diagnosis. Both Graves' disease and Hashimoto's thyroiditis share autoimmunity pathogenesis and the shift from one condition to another is possible.…”

“…Both Graves' disease and Hashimoto's thyroiditis share autoimmunity pathogenesis and the shift from one condition to another is possible. 13 However, the pathogenesis of Hashimoto's thyroiditis following Graves' disease has not been confirmed. Many theories were suggested.…”

A Review of Testing for Distinguishing Hashimoto’s Thyroiditis in the Hyperthyroid Stage and Grave’s Disease

“…The diagnosis relies upon good history and physical exam followed by supportive antibody titers and radioiodine uptake scan. 39 Continuous evaluation of TSAb levels is recommended in HT, particularly in cases of TSAb-positive and those under replacement, since it may help predict conversion to GD. 40 Distinct immune paradigms, paucity of functioning tissue in long-standing HT, and infrequent conversion of blocking (TSBAb) to stimulating (TSAb) thyrotrophin receptor antibody (TRAb) may account for this.…”

Development of hyperthyroidism in a hypothyroid patient

“…5 In a large observational retrospective case series by Gonzalez-Aguilera et al in 2018, 1.2% of patients with hypothyroidism developed Graves' disease. 6 This conversion has been seen predominantly in middle-aged women. 7…”