Investigations

Assessment of thyroid physiology:

• thyroid function tests - TSH, T4 or T3; mandatory in all patients with goitre

Assessment of thyroid morphology:

• chest X-ray - detection of tracheal compression
• chest CT - if suspect malignant change in a retrosternal thyroid
• ultrasound scan - differentiates solid, partly cystic and cystic changes

Assessment of thyroid pathology:

• isotope scan - now technetium rather than radio-iodine.
• fine needle aspiration biopsy: ultrasonographically-guided biopsy is both highly sensitive and specific for pathology when compared with definitive diagnosis at post-operative pathological examination

NICE have stated specific guidance regarding investigating thyroid enlargement with normal thyroid function:

Offer ultrasound to image palpable thyroid enlargement or focal nodularity in adults, children and young people with normal thyroid function if malignancy is suspected

Consider ultrasound of incidental findings on imaging if clinical factors suggest malignancy as a possibility.

When making decisions about whether to offer fine needle aspiration cytology, use an established system for grading ultrasound appearance that takes into account:

• echogenicity
• microcalcifications
• border
• shape in transverse
• plane
• internal vascularity
• lymphadenopathy

Reports of ultrasound findings should:

• specify which grading system has been used for the assessment
• include information on the features as stated above and provide an overall assessment of malignancy,
• and confirm that both lobes have been assessed,
• and document assessment of cervical lymph nodes.

Use ultrasound guidance when performing fine needle aspiration cytology

Reference:

• NICE (November 2019). Thyroid disease: assessment and management