We highlight the case of a 42 year old indigenous man from a remote town in Northern Territory with autoimmune thyroid disease, who had alternating hyperthyroid and hypothyroid states. He presented hypothyroid with sight-threatening thyroid orbitopathy, over ten years post an initial diagnosis of Graves’ disease. He then achieved a euthyroid state within months without medication therapy.
Hashimoto’s thyroiditis and Graves’ disease are autoimmune thyroid conditions. They have previously been thought of as two different disease processes, however it is now thought that they are on two ends of the autoimmune thyroid spectrum.1
In patients with alternating thyroid function between hyperthyroidism and hypothyroidism, blocking and stimulating TSH receptor antibodies are thought to be the cause. Both these antibodies can occur in the same patient, explaining variable clinical presentations, with alternating dominance between the two antibodies reported in the literature. The change of antibody dominance, and thus change in thyroid state, are related to the differences in concentration, affinity and potency of these antibodies.1 The most common scenario is the transition from Graves’ disease to Hashimoto’s thyroiditis.1,2 The presence of both blocking and stimulating antibodies may also explain periods of euthyroidism in these patients.3
Improved bioassay technologies are currently available which allows for the detection and measurement of TSH blocking and stimulating antibodies. The ability to measure these antibodies can be helpful in the interpretation of thyroid dysfunction, and management of patients with autoimmune thyroid disease.3 However, until such a time that these bioassays are readily accessible, the management of patients with autoimmune thyroid disease, and switching hyperthyroid and hypothyroid states can be challenging. In the absence of definitive management of their disease, regular blood tests and close monitoring is required.2