From the Guidelines
The workup for hyperthyroidism begins with thyroid function tests, specifically TSH, free T4, and free T3, as recommended by the US Preventive Services Task Force 1. A suppressed TSH with elevated free T4 and/or free T3 confirms hyperthyroidism. Once confirmed, determining the etiology is essential, which includes:
- Thyroid antibody testing (TSI, TRAb, anti-TPO, anti-thyroglobulin) to identify autoimmune causes like Graves' disease
- A radioactive iodine uptake scan to differentiate between conditions with increased uptake (Graves' disease) versus decreased uptake (thyroiditis)
- Thyroid ultrasound to identify nodules or structural abnormalities
- Complete blood count and comprehensive metabolic panel to assess for complications and rule out other causes
- Orbital imaging in patients with suspected Graves' ophthalmopathy
- ECG in elderly patients or those with cardiovascular symptoms to detect arrhythmias The workup should also include a thorough history and physical examination focusing on symptoms duration, medication use (including iodine-containing supplements), family history of thyroid disorders, and signs of thyroid eye disease or dermopathy. This comprehensive approach ensures accurate diagnosis and guides appropriate treatment selection among options like antithyroid medications (methimazole 5-30mg daily or propylthiouracil 100-300mg divided doses), radioactive iodine ablation, or surgical thyroidectomy, as supported by recent guidelines 1. In patients with immune-related adverse events, such as those treated with immune checkpoint inhibitor therapy, the management of hyperthyroidism may involve holding the therapy, beta-blockers for symptomatic relief, and endocrine consultation for additional workup and possible medical thyroid suppression 1.
From the Research
Diagnosis of Hyperthyroidism
- Hyperthyroidism is confirmed by biochemical tests, including low TSH, high free thyroxine (FT4), or high free tri-iodothyonine (FT3) 2, 3, 4, 5
- A nosological diagnosis is necessary to determine the underlying cause of hyperthyroidism, using tools such as TSH-receptor antibodies, thyroid peroxidase antibodies, thyroid ultrasonography, and scintigraphy 2
- Thyroid scintigraphy is recommended if thyroid nodules are present or the etiology is unclear 3
Causes of Hyperthyroidism
- The most common causes of hyperthyroidism are Graves' disease (70%) and toxic nodular goitre (16%) 2
- Other causes include subacute granulomatous thyroiditis (3%) and drugs such as amiodarone, tyrosine kinase inhibitors, and immune checkpoint inhibitors (9%) 2
- Toxic nodules can cause symptoms from local compression of structures in the neck, such as dysphagia, orthopnea, or voice changes 3
Treatment of Hyperthyroidism
- Treatment options for overt hyperthyroidism include antithyroid drugs, radioactive iodine ablation, and surgery 2, 3, 4, 6, 5
- Antithyroid drugs are the preferred treatment for Graves' hyperthyroidism, with a 12-18 month course of treatment 2, 6
- Radioactive iodine ablation is the most widely used treatment in the United States, and is often used for toxic nodular goitre 4
- Thyroidectomy is recommended for patients with large goiters or those who are pregnant and cannot take antithyroid drugs 6
- Treatment choices should be individualized and patient-centered, taking into account the underlying diagnosis, presence of contraindications, severity of hyperthyroidism, and patient preference 3, 4, 6