Color flow Doppler sonography in thyrotoxicosis factitia

Area of Science:

• Endocrinology
• Radiology
• Internal Medicine

Background:

• Hyperthyroidism, particularly Graves' disease, typically shows increased thyroid blood flow on Color Flow Doppler Sonography (CFDS).
• Thyrotoxicosis factitia results from exogenous thyroid hormone intake and presents a diagnostic challenge.
• CFDS is a valuable non-invasive imaging technique for assessing tissue vascularity.

Purpose of the Study:

• To evaluate the specific CFDS patterns in patients diagnosed with thyrotoxicosis factitia.
• To differentiate CFDS findings in thyrotoxicosis factitia from those in Graves' disease and healthy individuals.

Main Methods:

• CFDS was performed on five women with thyrotoxicosis factitia.
• Thyroid function tests (FT4, FT3, TSH), thyroid antibodies, thyroglobulin, radioiodine uptake, and urinary iodine were assessed.
• CFDS findings were compared with those of 26 women with untreated Graves' disease and 24 healthy controls.

Main Results:

• Patients with thyrotoxicosis factitia exhibited normal thyroid volume and echogenicity, with absent or minimal intrathyroidal vascularity on CFDS.
• Peak systolic velocity (PSV) in thyrotoxicosis factitia patients was within normal limits (mean 4 cm/sec).
• In contrast, Graves' disease patients showed significantly increased PSV (mean 12.9 cm/sec) and diffuse hypervascularity (p < 0.001).

Conclusions:

• CFDS demonstrates absent hypervascularity and normal PSV in thyrotoxicosis factitia, irrespective of the thyrotoxic state.
• These distinct CFDS patterns can help confirm the diagnosis of thyrotoxicosis factitia, differentiating it from other causes of hyperthyroidism.
• Due to its ease, speed, and non-invasive nature, CFDS is a useful first-line investigation for suspected thyrotoxicosis factitia.