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.
Suspicious features
Any patient with a solitary nodule, a suspicious or dominant nodule within a multinodular goitre, or palpated lymph nodes, requires urgent ultrasound guided aspiration according to international guidelines.
Patients with thyrotoxicosis and an isolated nodule
These patients should be assessed clinically and with ultrasound in the usual way, with fine needle aspiration performed if indicated.
If aspiration is not necessary, treatment is usually with radioactive iodine. If the nodule is shrinking at three months, no further assessment is indicated.
Patients with hypothyroidism and an isolated nodule
These patients should be assessed and the nodules aspirated if indicated. Thyroxine treatment should also be instituted and the nodule re-assessed at three months.
Fine needle aspiration results
Non diagnostic results on fine needle aspiration
Non diagnostic aspirations should be repeated on at least two further occasions three months apart, according to British Thyroid Association guidelines.
If results are non diagnostic on two occasions, consider surgery to establish a diagnosis.
Benign results on fine needle aspiration
Two benign results indicating thyroiditis, or benign nodular disease, are reassuring.
Many patients may then be discharged, or treated with radioactive iodine if there is thyrotoxicosis or other nodules detected.
This aims to shrink the nodules and treat the hyperthyroidism.
Follicular cells on fine needle aspiration
Any follicular results suggest a follicular neoplasm and require referral to a thyroid multidisciplinary team for consideration of hemithyroidectomy.
If histology confirms it to be a follicular adenoma then the patient can be discharged. If histology reveals a follicular carcinoma, completion thyroidectomy and radioactive iodine are required.
Results of fine needle aspiration suggestive, or diagnostic, of malignancy
Results diagnostic of malignancy require immediate referral to a thyroid multidisciplinary team for consideration of total thyroidectomy, followed by radioactive iodine if appropriate according to national thyroid cancer guidelines.
Results suggestive of malignancy should be repeated to establish a diagnosis, and also referred to a multidisciplinary team.
Pregnancy and fertility plans should be discussed with all patients
Nodules should be assessed and treated conventionally in pregnant patients, though surgery should be deferred to the second trimester in most cases.
Radioactive iodine treatment
This is the treatment of choice for most patients with multinodular goitres or thyrotoxicosis secondary to nodular disease. Radioactive iodine will prevent future growth and reduce the size of most goitres and solid nodules by up to 50%. Radioactive iodine is also the treatment of choice for hyperthyroidism due to nodular disease, which will otherwise require life long anti-thyroid drugs.
Radioactive iodine is contraindicated in pregnant or breast feeding individuals. Women should be advised to avoid conception for six months and men should avoid fathering children for four months following radioactive iodine treatment.
Post radioactive iodine monitoring and hypothyroidism
Thyroid function should be assessed at least every three months for the first year after radioactive iodine, and then annually thereafter for emerging hypothyroidism.
All patients should be warned that monitoring is required and that hypothyroidism develops in up to 70% of patients. Subsequent hypothyroidism should be treated conventionally.
Inadequate control of thyrotoxicosis by six months should prompt consideration of a repeat application of radioactive iodine.
Nodules should be shrinking within three months.
New growth or change in the characteristics of a nodule despite previous radioactive iodine should prompt reassessment as for a new nodule.
Thyroid surgery
Surgery should be discussed in all cases. Patients with a hyperfunctioning nodule who are unsuitable for, or decline, radioactive iodine may be offered a hemithyroidectomy. Sub-total thyroidectomy may be considered for multinodular goitres. Surgery is also appropriate after more than two non-diagnostic fine needle aspirations to establish a diagnosis, or after a Thy3, Thy4 or Thy5 aspiration result according to national guidelines.