Goitre

From Ganfyd

A goitre is the term for enlargement/hypertrophy of the Thyroid. In the UK, it is estimated that up to 15% of the population have a goitre. Of these, 8% have nodular thyroid disease, of which 50% are solitary. Although thyroidnodules are common, thyroid cancer is very rare.

The classic cause of goitre is lack of Iodine in the diet. Certain areas of the world have low Iodine content in the underlying rock and thus food grown there, Nepal is an example. In the UK iodination of common or table salt has abolished goitre.

Classification of goitres

• Simple (non-toxic)
• Toxic
• Inflammatory - Hashimoto's, De Quervain's, Reidel's thyroiditis
• Neoplastic - Benign and malignant
• Rare causes - Tuberculosis, syphilis, HIV, lithium

Simple goitre

Aetiology

• Iodine deficiency - rare in the UK
• Puberty
• Pregnancy
• Oral contraceptive pill
• May or may not be associated with hypothyroidism
• May be diffuse, nodular or multinodular

Investigations

• Ultrasound
• Fine needle aspiration
• Thyroid function tests

Treatment

• Dietry iodine replacement
• Thyroid surgery

Toxic goitre

Aetiology

• May be Grave's disease or solitary toxic nodule
• Plummer's disease is the development of thyrotoxicosis in a long-standing multinodular goitre

Investigations

• Thyroid scan
• Ultrasound
• Fine needle aspiration
• Thyroid function tests
• Thyroid autoantibodies

Treatment

• Medical
  • Treat hyperthyroidism with drugs such as carbimazole or propylthiouracil
  • Suppress euthyroid goitre size with Levothyroxine
    • Successful in 30-60% dependant on goitre size
• Radioiodine
  • Achieves 50% volume reduction at risk of hypothyroidism and unknown future malignancy risk
  • May be given with recombinant TSH to increase volume reduction at expense of more adverse effects^[1]
• Thyroid surgery
  • With non-toxic goitre reoccurs in 15-40%

Inflammatory goitre

There are three main types of inflammatory goitre.

Hashimoto's thyroiditis

• Most common in late middle-age women
• Antibodies against thyroglobulin or microsomal peroxidase
• Thyroid shows lymphocyte infiltration, atrophy and regeneration
• Gland is firm and rubbery
• Patients are initially hyperthyroid, but become hypothyroid as disease progresses
• Treated with thyroxine suppression and regularly monitored
• Risk factor for thyroid lymphoma

De Quervain's thyroiditis

• Thyroiditis secondary to an acute viral infection
• Flu like illness, followed by thyroid swelling and tenderness
• Transient hyperthyroidism and usually transient production of auto-antibodies

Riedel's thyroiditis

Described by German surgeon, Bernhard Moritz Carl Ludwig Riedel

• Rare
• Associated with woody, tender, fibrotic thyroid gland
• May be a reaction to an underlying thyroid cancer or lymphoma

It is now known to be one of the IgG4-related diseases.

Investigation of a thyroid lump

• Clinical examination
• Thyroid scan - shows if the lump is 'hot' (adenoma or benign nodule) or 'cold' (needs further investigations
• Ultrasound scan - shows if lump is solid, which needs fine needle aspiration, or cystic, which needs aspiration
• Fine needle aspiration - a good test, but must be used in conjunction with clinical history. A result of 'follicular adenoma' does not exclude follicular carcinoma of the thyroid and is an indication for hemithyroidectomy
• Aspiration - cellular fluid provides useful information about the nature of the lump

References