Euthyroid Goitre

Euthyroid goitre is an enlarged thyroid gland, diffuse or nodular, in a person whose thyroid hormone levels are normal. It is the commonest thyroid presentation worldwide and includes diffuse goitre, multinodular goitre and a single nodule in an enlarged gland. The central tasks are to confirm that thyroid function is normal, to exclude cancer, and to identify patients who need treatment for compression or appearance.

• Causes: iodine deficiency (endemic) or excess; goitrogens (cassava, cabbage, soy, smoking); autoimmune thyroiditis in the euthyroid phase; physiological enlargement at puberty and pregnancy; drugs (lithium, amiodarone, antithyroid drugs); genetic dyshormonogenesis; thyroid hormone resistance; and nodular transformation with age (multinodular goitre affects about 5 percent of adults in iodine sufficient areas, and up to 30 percent or more in iodine deficient areas).
• Natural history: slow growth over years, with nodule formation, functional autonomy and later thyrotoxicosis (toxic multinodular goitre, particularly after iodine load such as contrast media or amiodarone), cystic degeneration, and haemorrhage.
• Thyroid cancer risk in a multinodular goitre is about 5 percent, similar to a solitary nodule. Risk factors: age under 20 or over 60, male sex, family history of thyroid cancer, neck irradiation, rapid growth, hard fixed nodule, vocal cord paralysis, and cervical nodes.

• Visible neck swelling or a lump noticed incidentally, moving on swallowing; usually painless. Sudden pain suggests haemorrhage into a nodule or thyroiditis.
• Compression: dysphagia, dyspnoea (especially lying or with raised arms), stridor, choking, hoarseness, cough, positional dizziness.
• No features of hypothyroidism or hyperthyroidism (tremor, palpitations, weight loss, heat intolerance, tachycardia, atrial fibrillation indicate evolving toxic goitre).
• Examination: size, symmetry, nodularity, firmness, tenderness, retrosternal extension, bruit, lymph nodes; Pemberton sign (facial congestion, stridor on raising both arms), tracheal deviation.
• Red flags: rapid growth over weeks, firm fixed nodule, hoarseness, cervical lymphadenopathy, stridor, weight loss, a family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2, a history of neck irradiation, and age under 20.

• Thyroid stimulating hormone (and free thyroxine, free triiodothyronine when abnormal) to confirm euthyroidism; anti-thyroid peroxidase antibodies.
• Thyroid ultrasound with measurement of volume and each nodule's size, composition and features: solid, hypoechoic, irregular margins, microcalcifications, taller than wide shape, extrathyroidal extension, abnormal nodes suggest cancer; spongiform or purely cystic appearances are reassuring.
• Fine needle aspiration cytology of nodules with suspicious features at 1 cm or more, intermediate features at 1.5 cm or more, low suspicion at 2 cm or more; repeat when nodules grow by 20 percent in two dimensions or 50 percent in volume; aspirate the dominant or most suspicious nodule in multinodular goitre.
• Radionuclide scan (technetium or iodine-123) when thyroid stimulating hormone is low or suppressed, to identify hot nodules (rarely malignant).
• Computed tomography without contrast, or magnetic resonance imaging, for retrosternal or compressive disease; spirometry flow volume loop; laryngoscopy before surgery or for voice change.
• Calcitonin when family history or suspicious features.
• Differentials: Hashimoto thyroiditis, Graves disease, thyroid cancer (papillary, follicular, medullary, anaplastic, lymphoma), thyroid cyst, subacute thyroiditis, thyroglossal cyst, parathyroid adenoma, cervical lymph nodes.

Observation (most patients)

• Reassurance for small asymptomatic euthyroid goitres with benign cytology. Check clinical status and thyroid stimulating hormone every 12 months, and repeat ultrasound at 12 to 24 months, or earlier if growth, symptoms or a change in consistency.

Medical

• Iodine deficiency: iodised salt and diet; potassium iodide 150 micrograms daily in pregnancy, breastfeeding and deficient areas (check thyroid function 4 to 8 weeks after iodine supplements in nodular goitre).
• Levothyroxine suppression is not advised in iodine sufficient regions or in nodular goitre, because the benefit is small and risks (atrial fibrillation, bone loss) are real. In diffuse goitre in young patients (iodine deficient) it can be used for 6 to 12 months: 1 to 1.5 micrograms/kg daily, aiming at a thyroid stimulating hormone of 0.5 to 1.0 mIU/L; stop if no 20 to 30 percent volume reduction.
• Treat hypothyroidism if it develops: levothyroxine 1.6 micrograms/kg daily (start 25 to 50 micrograms in older people and cardiac disease), titrated every 6 to 8 weeks.
• Subclinical hyperthyroidism in nodular goitre: monitor thyroid stimulating hormone every 3 to 6 months; treat if thyroid stimulating hormone persistently below 0.1 mIU/L, atrial fibrillation, osteoporosis or age above 65.
• Toxic multinodular goitre: carbimazole 15 to 30 mg once daily (or methimazole 10 to 20 mg) to restore euthyroidism, with propranolol 10 to 40 mg three times daily for symptoms; definitive treatment with iodine-131 or surgery.

Procedures (specialist)

• Surgery: total or near total thyroidectomy for compression, retrosternal extension, suspicious or malignant cytology, large cosmetic goitre, or failure of other treatments. Complications: recurrent laryngeal nerve palsy (1 percent or less), hypocalcaemia (temporary 10 to 30 percent; permanent 1 to 3 percent), bleeding and wound infection. After total thyroidectomy give levothyroxine 1.6 micrograms/kg daily and check calcium and parathyroid hormone.
• Radioactive iodine (iodine-131) for toxic or large non-toxic goitres where surgery is not suitable; reduces size by about 35 to 50 percent in 1 year; risks hypothyroidism (up to 50 percent in 5 years), transient swelling and thyroiditis; avoid in pregnancy, breastfeeding, and when planning pregnancy within 6 to 12 months.
• Ultrasound directed ethanol injection for cystic nodules; radiofrequency or laser ablation for selected solid benign nodules causing symptoms.

Special groups

• Pregnancy: ultrasound and thyroid function tests each trimester; levothyroxine adjusted; no radioiodine; surgery in the second trimester if essential.
• Children and adolescents: refer to paediatric endocrinology; higher cancer risk in nodules.
• Older adults: toxicity from thyroid hormone is a greater risk (atrial fibrillation, osteoporosis); surgery risks depend on comorbidity.
• Amiodarone, lithium and contrast media: monitor thyroid function and stop or change where feasible.

Follow up

• Annual thyroid stimulating hormone and clinical review; repeat ultrasound at intervals according to risk; refer urgently for hoarseness, rapid growth, hard nodule, stridor or lymph nodes.