From the Guidelines
The best non-invasive test for diagnosing thyroiditis is a combination of thyroid function tests and thyroid ultrasound, particularly Doppler US, which can help distinguish between different causes of thyrotoxicosis, including thyroiditis, by evaluating thyroid blood flow. When evaluating thyroiditis, it is essential to consider the various non-invasive tests available, including:
- Thyroid function tests (TFTs), such as TSH, free T4, and free T3
- Thyroid antibody testing, including TPOAb and TgAb
- Thyroid ultrasound, which can reveal characteristic changes in thyroid texture, size, and vascularity associated with inflammation
- Doppler US, which can help differentiate between thyrotoxicosis caused by an overactive thyroid, such as Graves disease, and thyrotoxicosis caused by destructive causes, such as subacute or lymphocytic thyroiditis, as it shows increased and decreased thyroid blood flow, respectively 1. The use of Doppler US is supported by a study that found similar sensitivity and specificity for Doppler US (95% and 90%) and radionuclide uptake studies (90% and 100%) in distinguishing between these causes of thyrotoxicosis 1. However, it is crucial to note that while these tests are valuable for diagnosing thyroiditis, they should be used in conjunction with clinical evaluation and other diagnostic tools to ensure accurate diagnosis and effective management. In the context of the provided options, B. Ultrasound and Doppler is the most appropriate choice for a non-invasive test for diagnosing thyroiditis, as it can provide valuable information about thyroid morphology, vascularity, and blood flow, which can aid in distinguishing between different causes of thyroiditis 1.
From the Research
Non-Invasive Tests for Thyroiditis
The following options are available for non-invasive testing for thyroiditis:
- Ultrasound and Doppler: This method is supported by several studies, including 2, which found that De Quervain's subacute thyroiditis can be conclusively diagnosed by sonography in more than 90% of cases based on history, typical clinical features, and clinical test parameters indicating signs of inflammation. Colour Doppler sonography can be useful in differential diagnosis of unclear cases.
- Other options: There is no evidence to support the use of Thoracic inlet X-ray or Snapping pictures for diagnosing thyroiditis.
- FNAC (Fine-Needle Aspiration Cytology): While FNAC is a common diagnostic tool for thyroid nodules, it is considered a minimally invasive procedure and may not be suitable for all patients.
Key Findings
- Ultrasound and Doppler imaging can provide valuable information for the diagnosis of thyroiditis, including the assessment of thyroid vascularity and morphology 3, 4.
- Superb microvascular imaging can allow for the assessment of subtle vascularity changes in early stages of Hashimoto's thyroiditis 3.
- Photoacoustic/ultrasound dual imaging may provide complementary information for traditional ultrasound thyroid examination 5.
Available Evidence
The available evidence suggests that Ultrasound and Doppler is a suitable non-invasive test for diagnosing thyroiditis, as supported by studies 2, 3, 4, 6.