A 45-year-old woman comes to the clinic for a routine wellness examination. She has no acute complaints and reports feeling well. Her medical history is unremarkable, and she takes no medications. Vital signs are within normal limits. Physical examination reveals a palpable, non-tender, 1.5-cm nodule in the right lobe of the thyroid gland. The nodule moves with swallowing. No cervical lymphadenopathy is appreciated. Which of the following is the most appropriate next step in the diagnostic workup of this patient?
- Measurement of serum thyroid-stimulating hormone (TSH) and thyroid ultrasonographyAnswer
- BFine-needle aspiration biopsy of the nodule
- CRadioactive iodine scintigraphy
- DComputed tomography (CT) scan of the neck with contrast
- EReassurance and follow-up examination in 6 months
Answer
Measurement of serum thyroid-stimulating hormone (TSH) and thyroid ultrasonography
The most appropriate initial step in the evaluation of a newly discovered thyroid nodule is the measurement of serum TSH and a thyroid ultrasound. The TSH level determines the functional status of the thyroid, which heavily influences the subsequent workup. A subnormal TSH suggests a hyperfunctioning ('hot') nodule, which requires radioactive iodine scintigraphy. A normal or elevated TSH prompts evaluation of the ultrasound features to determine if fine-needle aspiration (FNA) is warranted. Ultrasound provides critical anatomic details (e.g., solid vs. cystic, microcalcifications, irregular margins) that cannot be determined by physical examination alone.
Step-by-Step Solution
Key Concept
The initial evaluation of all newly discovered thyroid nodules requires measurement of serum TSH (to assess functional status) and a thyroid ultrasound (to assess anatomic features and malignancy risk).