From the Guidelines
Testing for Graves' disease primarily involves blood tests measuring thyroid hormone levels and thyroid-stimulating immunoglobulins, with the initial screening including TSH, free T4, and T3 levels, and the definitive test being TSH receptor antibodies (TRAb) 1. The diagnostic approach for Graves' disease involves several key steps:
- Initial screening with TSH, which is typically suppressed, along with elevated free T4 and T3 levels
- Measuring TSH receptor antibodies (TRAb), which are present in about 95% of Graves' patients
- Additional testing may include thyroid peroxidase antibodies (TPO) and thyroglobulin antibodies, which are often elevated in autoimmune thyroid conditions
- Radioactive iodine uptake scans can help confirm the diagnosis by showing diffusely increased uptake throughout the thyroid gland
- Thyroid ultrasound may be performed to evaluate gland size and texture, typically revealing an enlarged, heterogeneous gland with increased vascularity
- Complete blood count and metabolic panels are also recommended to assess for complications Some key points to consider in the diagnostic process include:
- The serum TSH test is the primary screening test for thyroid dysfunction, with multiple tests done over a 3- to 6-month interval to confirm or rule out abnormal findings 1
- The optimal screening interval for thyroid dysfunction is unknown, but the USPSTF recommends screening for thyroid dysfunction in asymptomatic persons, particularly those with a history of thyroid disease or treatment 1
- Treatment for hyperthyroidism is generally recommended for patients with a TSH level that is undetectable or less than 0.1 mIU/L, particularly those with overt Graves disease or nodular thyroid disease 1
- Early diagnosis is crucial as untreated hyperthyroidism can lead to serious cardiac complications, bone loss, and in rare cases, thyroid storm 1
From the Research
Diagnostic Tests for Graves' Disease (Hyperthyroidism)
The diagnostic tests for Graves' disease (hyperthyroidism) include:
- Biochemical tests, such as low TSH, high free thyroxine (FT4), or high free tri-iodothyonine (FT3) 2
- Measurement of TSH-receptor antibodies (TSH-R-Ab) to confirm the diagnosis of Graves' disease 3, 4, 5, 6
- Thyroid ultrasonography to assess the thyroid gland and detect any abnormalities 2, 4, 5, 6
- Scintigraphy to evaluate thyroid function and differentiate between causes of thyrotoxicosis 2, 5, 6
- Thyroid-stimulating hormone (TSH) test to assess thyroid function 6
- Free T4 and free T3 assays to assess biological severity and monitor treatment efficacy 6
Specific Diagnostic Tests
- TSH-R-Ab measurement is recommended for an accurate diagnosis and differential diagnosis of Graves' disease 3, 4, 5, 6
- Thyroid scintigraphy is reserved for rare cases of Graves' disease with negative antibody findings or when another etiology is suspected 6
- Thyroid ultrasound scan may be contributive, but is not recommended in first line 6
- TRAb assays can be alternatively adopted to differentiate causes of thyrotoxicosis, limiting the use of thyroid scintigraphy to TRAb-negative patients 5
Diagnostic Criteria
- A diagnosis of Graves' disease can be made based on clinical presentation, biochemical tests, and measurement of TSH-R-Ab 3, 4, 6
- The presence of extra-thyroid signs, such as orbitopathy, can support the diagnosis of Graves' disease 3, 6
- A thyroid ultrasound scan showing a hypervascular and hypoechoic thyroid gland can also support the diagnosis of Graves' disease 3