Thyroid nodule

Any individual mass palpable within the thyroid gland. Nodules are typically benign, may be hyperfunctioning, and may occur within a multinodular goitre, but always require assessment for possible malignancy. Diagnosis is usually clinical but assessment should always include serum hormone testing, and may require uptake scanning or ultrasound guided fine needle aspiration.

Baseline investigations - all patients

Full blood count

Useful indicator of general health and underlying disease, notably malignancy.

Urea and electrolytes

Useful indicator of general health and underlying disease.

Liver function test

Liver function should be tested at baseline, and abnormalities should prompt detailed evaluation in case of disseminated malignancy.

Bone profile

Hypercalcaemia may occur with thyrotoxicosis but also occurs in malignancy.

Thyroid stimulating hormone

A low thyroid stimulating hormone in the presence of a single thyroid nodule is highly suggestive of a toxic nodule.

Free thyroxine

Thyroid stimulating hormone and free thyroxine should be tested together in patients with suspected thyroid disease as the level of thyroxine indicates the severity of thyrotoxicosis and informs treatment.

Electrocardiogram

ECG should be performed in all patients at baseline to document and confirm any arrhythmias or other changes.

Thyroid auto-antibody screen

If the entire gland feels like a single hard lump it may be Hashimoto’s thyroiditis rather than a nodule. Thyroid peroxidise antibodies are generally very high in such cases.  

Free liothyronine

Free liothyronine levels may be useful if the thyroid stimulating hormone is suppressed, but the thyroxine level is normal, to confirm the suspicion of a toxic nodule.

Further investigations - selected cases only

Calcitonin

This should be tested if medullary cell thyroid cancer is suspected.

Parathyroid hormone

If serum calcium is elevated, it is useful to check PTH to determine the cause.

Bone densitometry

Bone mineral density should be assessed where there is clinical suspicion of osteoporosis, for example in some older patients with a toxic nodule.

Vitamin D levels

In patients with known or suspected osteoporosis, serum vitamin D levels will guide whether routine calcium and vitamin D supplementation is enough, or whether specific high dose vitamin D replacement is required.

Thyroglobulin

This test is not appropriate in patients presenting with a thyroid nodule.

This should only be assessed in patients with documented thyroid cancer, and only after thyroidectomy and radioactive iodine ablation. In this case it is a useful guide for future monitoring and treatment.

Thyroid ultrasound scan

Ultrasound scan should be performed in all patients presenting with a single palpable nodule.

The scan may reveal the presence of other nodules within the gland, lymph nodes and may provide useful information about the character of the nodule itself, for example micro-calcification, comet sign or cystic components.

Ultrasound scanning should also confirm whether fine needle aspiration is necessary and guide this procedure.

Chest radiograph

This is essential in the investigation of patients with potential malignancy and is useful if tracheal deviation is suspected clinically.

Ultrasound guided fine needle aspiration

Guidelines are available recommending when fine needle aspiration should be performed. Fine needle aspiration should always be performed on solitary nodules over 10mm, those under 10mm with suspicious imaging characteristics or on dominant nodules.

Ultrasound guidance improves the safety of this procedure, increases the yield of this investigation by targeting specific areas of a nodule and allows treatment, for example aspiration of cyst contents at the same time as sampling solid components.

Ultrasound scanning may also identify patients in whom fine needle aspiration is not necessary.

Computerised tomography of the neck and chest

This is not usually required in the assessment of a solitary nodule.

Bone densitometry

Bone mineral density should be assessed where there is clinical suspicion of osteoporosis, for example in some older patients with biochemical thyrotoxicosis.

Vitamin D levels

In patients with known or suspected osteoporosis, serum vitamin D levels will guide whether routine calcium and vitamin D supplementation is enough, or whether specific high dose vitamin D replacement is required.

Thyroid radionucleide uptake scan

This may be performed in patients with thyrotoxicosis and a thyroid nodule.

A hot nodule is more likely to represent a hyperfunctioning follicular adenoma, but this does not obviate the need for a fine needle aspiration if otherwise indicated.

Isolated cold nodules should always be assessed for malignancy.

Laryngoscopic examination of the vocal cords

This should be performed by an experienced surgeon in all patients being considered for thyroid surgery.