Radioiodine thyroid ablation in graves' hyperthyroidism: merits and pitfalls

Area of Science:

• Endocrinology
• Nuclear Medicine
• Immunology

Background:

• Graves' disease (GD) treatment often involves radioiodine ablation, but its effects on ophthalmopathy and autoimmune responses require further study.
• Limited data exist on the clinical and biochemical outcomes of radioiodine therapy (RIT) for GD.

Purpose of the Study:

• To evaluate thyroid function, TSH-receptor antibodies (TRAb), and the occurrence of Graves' ophthalmopathy (GO) following radioiodine thyroid ablation in GD patients.
• To assess the effectiveness of RIT as a primary endpoint and the evolution of TRAb and GO as secondary endpoints.

Main Methods:

• A retrospective review of 162 patients with GD treated with iodine-131 (370–740 MBq) over six years.
• Data analysis focused on RIT success rates, TRAb levels, and GO incidence, comparing outcomes based on various clinical factors.

Main Results:

• RIT achieved an 88.3% success rate in treating hyperthyroidism within six months.
• RIT failure was associated with goiter (aOR=4.1).
• TRAb levels decreased over time (r=-0.147), with lower levels in successful treatment outcomes.
• Graves' ophthalmopathy (GO) developed in 3.7% of patients, particularly those with early hypothyroidism, antithyroid drug intolerance, and high TRAb levels.

Conclusions:

• Ablative radioiodine therapy is effective for Graves' hyperthyroidism.
• GO occurrence is a potential risk, especially in patients experiencing early hypothyroidism and high TRAb levels or antithyroid drug intolerance.
• Early introduction of levothyroxine (LT4) is recommended for patients at risk to mitigate radioiodine-induced hypothyroidism.