Recurrent Subacute Thyroiditis in a Patient With Human Leukocyte Antigen-associated Predisposition to Graves Disease

Subacute thyroiditis (SAT) followed by Graves disease (GD) is a rare condition. We report the case of a patient with recurrent SAT with human leukocyte antigen (HLA)-associated predisposition to GD.

A 28-year-old Japanese woman presented with neck pain and hyperthyroidism symptoms. We observed elevated C-reactive protein and thyroid hormone levels, along with a high erythrocyte sedimentation rate. Further, anti-thyroid-stimulating hormone receptor antibody was undetected, and thyroid glands were heterogeneous and hypoechoic. These findings confirmed a diagnosis of SAT. The patient was treated with prednisone (starting dose, 30 mg), and clinical and laboratory data suggested an improvement. Six months later, the patient presented with recurrent clinical and biochemical features of hyperthyroidism (thyroid-stimulating hormone level, 0.003 mIU/mL; free thyroxine level, 3.14 ng/dL; and TSH receptor-stimulating autoantibodies, 220%). The patient was diagnosed with GD and was successfully treated with methimazole. Eleven years later, the patient was diagnosed with simultaneous SAT and GD. HLA-typing revealed that the patient possessed characteristic alleles associated with susceptibility to GD, such as HLA-DRB1∗04:03 and ∗15:01, DQB1∗03:02:01 and 06:02:01, and HLA DPB1∗05:01 alleles.

The occurrence of SAT may trigger thyroid antigen release and lead to the onset of GD in patients who are genetically predisposed to this autoimmune disorder.

For certain patients, the diagnosis of GD should be considered in case of recurrent hyperthyroidism and history of resolved SAT.