From the Guidelines
The workup for hyperthyroidism should start with thyroid function tests, including TSH and free T4, as recommended by the USPSTF 1, 2. The initial step in evaluating hyperthyroidism involves assessing thyroid function through blood tests.
- Thyroid-stimulating hormone (TSH) levels are typically low in hyperthyroidism.
- Free T4 (FT4) and free T3 (FT3) levels are usually elevated in hyperthyroidism. Further testing may include:
- Radioactive iodine uptake (RAIU) test and thyroid scan to determine the cause of hyperthyroidism, such as Graves' disease or toxic nodular goiter.
- Thyroid antibody tests, including TSI (thyroid-stimulating immunoglobulin) or TRAb (TSH receptor antibody) for Graves' disease, and anti-TPO (anti-thyroid peroxidase) and anti-thyroglobulin antibodies for autoimmune thyroid disorders.
- Complete blood count (CBC) and metabolic panel to assess overall health and rule out other conditions.
- Thyroid ultrasound to evaluate thyroid nodules or gland enlargement. Additional tests may be ordered based on clinical presentation and initial results, such as:
- Thyroid biopsy if nodules are present
- Electrocardiogram (ECG) to assess heart rhythm
- Bone density scan to check for osteoporosis in long-standing hyperthyroidism The goal of the workup is to confirm the diagnosis, determine the underlying cause, and assess the severity of hyperthyroidism, guiding treatment decisions that may include antithyroid medications, radioactive iodine therapy, or surgery, depending on the specific cause and patient factors, as noted in the guidelines 1, 2.
From the Research
Diagnostic Workup for Hyperthyroidism
The diagnostic workup for hyperthyroidism typically begins with a thyroid-stimulating hormone (TSH) level test 3. If the test results are uncertain, measuring radionuclide uptake can help distinguish among possible causes 3. The following tests may be used to diagnose hyperthyroidism:
- Thyroid function tests, including TSH, free thyroxine (FT4), and free tri-iodothyonine (FT3) 4, 5, 6
- Thyrotropin-receptor antibody test to diagnose Graves' disease 4, 6
- Thyroid ultrasonography to evaluate the thyroid gland 4, 7
- Scintigraphy to evaluate thyroid function and structure 4, 7
- Fine needle aspiration biopsy (FNA) for nodular goiter 7
Etiology of Hyperthyroidism
The most common cause of hyperthyroidism is Graves' disease, which accounts for approximately 70% of cases 4. Other causes of hyperthyroidism include:
- Toxic nodular goiter (16%) 4
- Subacute granulomatous thyroiditis (3%) 4
- Drugs, such as amiodarone, tyrosine kinase inhibitors, and immune checkpoint inhibitors (9%) 4
- Thyroiditis, which can cause transient hyperthyroidism 3
Treatment of Hyperthyroidism
Treatment options for hyperthyroidism depend on the underlying cause and may include: