1. Ask your GP or the radiologist for the nodule size in millimetres and whether there were any suspicious neck lymph nodes or local invasion. Your report does not suggest either.
2. Check a blood TSH level. If it is low, a thyroid uptake scan may be appropriate; if normal or high, the next test, if needed, is ultrasound. Harrison’s Principles of Internal Medicine, p. 785.
3. Consider a dedicated thyroid ultrasound if:
   • the nodule is 1.5 cm or larger if you are age 35 or over, or 1 cm or larger if under 35
   • CT shows suspicious findings such as abnormal neck lymph nodes, invasion outside the thyroid, or PET avidity
   • you have a strong thyroid-cancer risk factor, such as prior neck radiation, a close family history of thyroid cancer/MEN2, or rapid growth/voice or swallowing symptoms.

Practical next step

1. Check the CT images/report with radiology for:
   • exact thyroid nodule size
   • whether calcification is coarse/rim versus punctate
   • any suspicious cervical lymph nodes or local invasion
     Ask for an addendum if size is not stated.
2. Send TSH during admission, unless recently available.
   • If low TSH, discuss with or refer to Endocrinology for thyrotoxicosis work-up and consideration of radionuclide imaging.
   • If normal/high TSH, biochemical endocrinology input is not normally required.
3. If the nodule is not clinically palpable and has no suspicious CT features, document it and arrange routine outpatient thyroid ultrasound, either requested directly if that is your trust pathway or via GP at discharge. Ultrasound determines risk category and whether US-guided FNA is appropriate. Thyroid nodule assessment is based on TSH plus ultrasound, with FNA guided by ultrasound appearance and size. Harrison’s Principles of Internal Medicine, p. 785.

Which specialty?

• ENT / Head-and-Neck surgery: usual referral specialty for a focal thyroid nodule requiring assessment, ultrasound-guided FNA, or suspected thyroid cancer. In many UK systems this is via the thyroid or head-and-neck one-stop clinic.
• Endocrinology: refer if there is suppressed TSH/hyperthyroidism, significant goitre with thyroid dysfunction, or an established endocrine thyroid condition.
• Do not refer Oncology for this incidental CT finding.

Use a 2-week-wait suspected cancer referral to ENT/Head and Neck if

• an unexplained palpable thyroid lump, especially enlarging
• ultrasound is suspicious
• suspicious nodes, extrathyroidal extension, or PET avidity
• hoarseness, dysphagia, dyspnoea/stridor, or rapidly enlarging neck swelling.

• Check recent TSH and free T4, or send them if not available and clinically appropriate.
• Continue usual levothyroxine unless thyroid tests indicate under- or over-replacement.
• A suppressed TSH in this setting may simply reflect excess levothyroxine, so interpret it with FT4 and medication history. It does not automatically mean the nodule is autonomous.
• Document the incidental finding clearly in the discharge summary and communicate it to the GP.

• No urgent inpatient referral if the nodule is small, non-palpable, there are no suspicious neck nodes or invasive features on CT, and no hoarseness, dysphagia, stridor, or rapidly enlarging neck mass.
• If follow-up is needed based on the actual CT size or suspicious radiology features, refer to the local ENT/Head and Neck thyroid pathway for thyroid ultrasound +/- ultrasound-guided FNA. Some trusts route thyroid nodules through Endocrinology, so follow local pathway.
• Refer Endocrinology only if thyroid function is difficult to control, TSH is persistently suppressed/elevated despite dose adjustment, there is diagnostic uncertainty, or local services specifically triage nodules there.

Incidental small calcified left thyroid nodule on CT TAP. No cervical adenopathy or invasive features reported. Known primary hypothyroidism treated with levothyroxine. Check/review TSH and FT4; continue levothyroxine with routine dose adjustment as indicated. No acute inpatient action required. GP to review CT nodule size and arrange thyroid ultrasound or ENT/thyroid clinic assessment only if clinically palpable, size/suspicious radiological features warrant this, or new compressive/voice symptoms develop.