When suspicious of Graves' disease, how to order an ultrasound of the thyroid gland?

Thyroid Ultrasound in Suspected Graves' Disease

When suspecting Graves' disease, ultrasound of the thyroid gland should be ordered as a complementary diagnostic test to radioactive iodine uptake studies, as it provides valuable information about thyroid morphology and vascularity that can help confirm the diagnosis and guide treatment planning. 1

Diagnostic Approach for Suspected Graves' Disease

Initial Laboratory Testing

1. TSH and Free T4 testing should be performed first in patients with suspected hyperthyroidism 1
2. Thyroid-stimulating hormone receptor antibodies (TRAbs) measurement to confirm Graves' disease 1, 2

Imaging Studies

Thyroid Ultrasound

• Order as: "Thyroid ultrasound with Doppler flow"
• Clinical indication: "Suspected Graves' disease" or "Hyperthyroidism evaluation"
• Specific findings to request assessment for:
  • Thyroid gland size and dimensions (for RAI treatment planning) 1
  • Diffuse enlargement pattern
  • Vascularity (increased blood flow on Doppler is characteristic of Graves') 1
  • Presence of nodules requiring further evaluation 1

Radioactive Iodine Uptake and Scan

• Should be ordered in conjunction with ultrasound for complete evaluation
• Helps differentiate Graves' disease from other causes of thyrotoxicosis 1
• I-123 is preferred over I-131 due to superior imaging quality 1

Clinical Value of Thyroid Ultrasound in Graves' Disease

Thyroid ultrasound provides several key benefits in the evaluation of suspected Graves' disease:

• Confirms diffuse thyroid enlargement characteristic of Graves' disease 3
• Demonstrates increased vascularity on Doppler ultrasound (95% sensitivity, 90% specificity for differentiating causes of thyrotoxicosis) 1
• Identifies any concurrent nodules that may require biopsy 1
• Provides thyroid dimensions needed for radioactive iodine treatment planning 1
• Helps distinguish between Graves' disease and other causes of hyperthyroidism 1

Important Considerations and Pitfalls

• While Doppler ultrasound shows high sensitivity and specificity (95% and 90% respectively) for differentiating causes of thyrotoxicosis, radioiodine uptake studies are still preferred as they directly measure thyroid activity rather than inferring it based on blood flow 1
• Ultrasound alone is insufficient for definitive diagnosis of Graves' disease - laboratory confirmation with TRAbs is essential 2
• Pregnant women with suspected Graves' disease should be monitored with ultrasound for fetal goiter only if problems are detected; routine ultrasound screening is not necessary 1
• Ultrasound findings must be correlated with clinical presentation and laboratory results for accurate diagnosis 1

By following this approach, you can appropriately order and utilize thyroid ultrasound as part of a comprehensive evaluation for suspected Graves' disease, which will help guide treatment decisions and improve patient outcomes.