From the Guidelines
The patient's condition is most likely caused by stimulatory TSH antibodies, which are a hallmark of Graves' disease, an autoimmune disorder characterized by diffuse goiter, exophthalmos, and hyperthyroidism. The pathophysiology of this condition involves autoantibodies (TSI/TRAb) that bind to TSH receptors, stimulating excessive thyroid hormone production and causing orbital inflammation and fibroblast proliferation in the eye tissues 1. Management involves controlling thyroid hormone overproduction through antithyroid medications, radioactive iodine therapy, or surgery. First-line treatment typically begins with antithyroid medications such as methimazole (starting at 10-30 mg daily) or propylthiouracil (PTU, 100-300 mg daily in divided doses) 1. Beta-blockers like propranolol (20-40 mg every 6 hours) can provide symptomatic relief of adrenergic symptoms while waiting for antithyroid medications to take effect 1. Methimazole is preferred except during the first trimester of pregnancy when PTU is recommended. Treatment typically continues for 12-18 months, after which approximately 50% of patients achieve remission. For those who relapse or cannot tolerate medications, definitive treatment with radioactive iodine (typically 10-15 mCi of I-131) or thyroidectomy should be considered. The exophthalmos may require separate management including lubricating eye drops, selenium supplementation (200 mcg daily), glucocorticoids for severe cases, or orbital decompression surgery if vision is threatened 1. Regular monitoring of thyroid function tests is essential during treatment to adjust medication dosing and prevent hypothyroidism. Key points to consider in management include:
- Controlling thyroid hormone overproduction
- Managing exophthalmos
- Preventing hypothyroidism
- Monitoring thyroid function tests regularly
- Considering definitive treatment with radioactive iodine or thyroidectomy for those who relapse or cannot tolerate medications.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Pathophysiology of Diffuse Goiter and Exophthalmos
The patient's presentation of diffuse goiter and exophthalmos is consistent with Graves' disease, an autoimmune disorder that causes hyperthyroidism 2, 3. The pathophysiology of this condition involves:
- The production of thyroid-stimulating antibodies (TSAb) that stimulate the thyroid gland to produce excess thyroid hormones 2
- The activation of T helper (Th)1 immune response, which plays a key role in the immune-pathogenesis of Graves' disease and its extrathyroidal manifestations, such as Graves' ophthalmopathy (GO) 2
- The stimulation of the thyroid gland by TSAb, leading to an increase in thyroid hormone production and release 4, 3
Management of Hyperthyroidism
The management of hyperthyroidism due to Graves' disease involves:
- Antithyroid medications, such as methimazole and propylthiouracil, to reduce thyroid hormone production 4, 5
- Radioactive iodine ablation of the thyroid gland, which is the most widely used treatment in the United States 4
- Surgical thyroidectomy, which may be considered in certain cases 4, 3
- Treatment of extrathyroidal manifestations, such as GO, with medications like rituximab and teprotumumab 2
Answer to the Question
Based on the evidence, the correct answer is: b. Stimulatory TSH antibodies, as the pathophysiology of Graves' disease involves the production of TSAb that stimulate the thyroid gland to produce excess thyroid hormones 2. T lymphocyte stimulation is also involved in the immune-pathogenesis of Graves' disease, but it is not the primary mechanism underlying the production of excess thyroid hormones 2.