When is a thyroid ultrasound recommended for patients with Hashimoto's thyroiditis?

Thyroid Ultrasound in Hashimoto's Thyroiditis

Thyroid ultrasound is not routinely indicated for the diagnosis or management of uncomplicated Hashimoto's thyroiditis in adults, as imaging does not help differentiate among causes of hypothyroidism and does not change clinical management. 1

When Ultrasound IS Indicated

Thyroid ultrasound should be performed in patients with Hashimoto's thyroiditis under the following specific circumstances:

Presence of Thyroid Nodules

• Any palpable thyroid nodule requires ultrasound evaluation to assess for suspicious features of malignancy, regardless of the underlying Hashimoto's diagnosis 2, 3
• Ultrasound is the preferred first-line imaging modality for characterizing nodules and identifying high-risk features including microcalcifications, irregular borders, and central hypervascularity 2
• Patients with Hashimoto's thyroiditis have coexisting thyroid nodules that may harbor malignancy, and ultrasound cannot definitively distinguish benign from malignant nodules without tissue diagnosis 2, 4

Atypical Clinical Presentation

• When clinical presentation is atypical or does not fit the typical pattern of Hashimoto's thyroiditis, ultrasound may help identify alternative diagnoses 3
• If there is concern for coexisting thyroid malignancy based on clinical features, ultrasound evaluation is warranted 3

Goiter with Obstructive Symptoms

• Ultrasound is appropriate when suspected goiter presents with obstructive symptoms such as dyspnea, orthopnea, dysphagia, or dysphonia 3
• This helps confirm thyroid origin and characterize morphology to guide management decisions 3

When Ultrasound Is NOT Indicated

Routine Hypothyroidism Workup

• There is no role for ultrasound imaging in the routine workup of hypothyroidism in adults 1
• Imaging for thyroid morphology does not help differentiate among causes of hypothyroidism, and all causes will show decreased radioiodine uptake 1
• The diagnosis of Hashimoto's thyroiditis is primarily clinical and laboratory-based (elevated TSH, positive antithyroid antibodies) 3

Screening Without Clinical Indication

• Ultrasound should not be used for screening purposes in asymptomatic patients with Hashimoto's thyroiditis who have no palpable abnormalities 3
• Most thyroiditis cases can be diagnosed clinically with laboratory confirmation alone using thyroid function tests 3

Management of Identified Nodules

When ultrasound identifies nodules in patients with Hashimoto's thyroiditis:

• Apply established risk stratification criteria (such as ACR TI-RADS or ATA guidelines) to determine which nodules require fine-needle aspiration 2
• Suspicious ultrasound features warrant FNA regardless of the Hashimoto's diagnosis 2
• Ultrasound-guided FNA is superior to palpation-guided FNA in this population, with 100% sensitivity for detecting malignancy versus missing papillary carcinomas with palpation alone 4
• Hypoechoic nodules have higher malignancy risk, while hyperechoic nodules are usually benign 4

Common Pitfalls to Avoid

• Do not skip ultrasound evaluation when a discrete nodule is palpable, even if the patient has confirmed Hashimoto's thyroiditis—coexisting malignancy can be missed 4
• Do not order ultrasound reflexively for every patient with newly diagnosed Hashimoto's thyroiditis if there are no palpable nodules or atypical features—this wastes resources without changing management 1, 3
• Do not rely on radionuclide scanning to evaluate hypothyroidism or differentiate causes of thyroiditis, as all causes show decreased uptake 1
• Be aware that only 1.4% of patients with Hashimoto's thyroiditis have completely normal thyroid ultrasound findings, but abnormal ultrasound appearance alone (heterogeneous echotexture) does not require intervention 5