From the Guidelines
Graves' disease is characterized by laboratory findings of suppressed thyroid-stimulating hormone (TSH) levels, typically less than 0.1 mIU/L, and elevated free thyroxine (FT4) and free triiodothyronine (FT3) levels, with positive thyroid-stimulating immunoglobulin (TSI) or thyroid-stimulating hormone receptor antibodies (TRAb) confirming the autoimmune nature of the condition. The primary tests for diagnosing Graves' disease include:
- Thyroid-stimulating hormone (TSH) levels, which are usually suppressed (<0.1 mIU/L) 1
- Elevated free thyroxine (FT4) and free triiodothyronine (FT3) levels
- Thyroid-stimulating immunoglobulin (TSI) or thyroid-stimulating hormone receptor antibodies (TRAb), which are specific markers for Graves' disease Additional tests may include:
- Thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb), which are often elevated in autoimmune thyroid conditions
- Complete blood count and liver function tests, which may be ordered before initiating treatment
- Radioactive iodine uptake scan, which can help confirm diagnosis by showing diffuse increased uptake throughout the thyroid gland, although it is not a laboratory test 1. These tests collectively help differentiate Graves' disease from other causes of hyperthyroidism, as the presence of TSI/TRAb antibodies is specific to Graves' disease and indicates autoimmune stimulation of the thyroid gland causing excessive hormone production. It is essential to note that the diagnosis and management of Graves' disease should be based on the most recent and highest-quality evidence, and treatment should be individualized to minimize morbidity, mortality, and improve quality of life 1.
From the Research
Laboratory Findings in Graves' Disease
The laboratory findings in Graves' disease, also known as hyperthyroidism, include:
- Low serum TSH concentrations, which is the most reliable indicator of thyroid function 2
- Elevated serum levels of FT4, which is a more accurate measure of thyroid function than total T4 (TT4) 2
- Elevated serum levels of FT3, although its measurement is not as significant as T3 2
- Presence of serum autoantibodies against thyroid tissues, such as TgAb and TPOAb 2
- Presence of TSH receptor antibodies, which differentiate Graves' disease from Hashimoto's thyroiditis 2, 3, 4
- Elevated serum levels of TRAb, which can be measured by radioreceptor assay or bioassay using cultured porcine thyroid cells 2, 3, 4
Diagnostic Tests
The diagnostic tests for Graves' disease include: