Thyroid Disease

Question 1

Where is thyroid stimulating hormone released and what does it stimulate?

What do these hormones do?

Answer 1

Thyroid stimulating hormone (TSH) is released by anterior pituitary gland and stimulates thyroid gland to release thyroxine (T4) and tri-iodothyronine (T3)

T3 is the active form of the hormone

T4 is de-iodinated in target cells to T3

Thyroid hormones stimulate an increase in metabolic rate of many tissues

Question 2

What are the two thyroid disease states?

How are thyroid diseases investigated?

Answer 2

Hypothyroidism: too little thyroid hormone, makes metabolic rate slow

Hyperthyroidism: too much thyroid hormone, makes metabolic rate fast

Investigations:

• blood tests: TSH, T3, T4, autoantibodies
• Imaging: USS, nuclear medicine

Question 3

How is hypothyroidism most commonly caused?

List some less common causes:

Answer 3

Most common causes: autoimmune disease with thyroid auto-antibodies

• atrophic thyroiditis
• hashimotos thyroiditis
• more common in females

Less common causes:

• congenital hypothyroidism (when babies are born, screened for with heel prick test)
• iodine deficiency
• drug side effects
• hypopituitarism
• after DXT
• infiltration by tumour

Question 4

List some features of hypothyroidism:

Answer 4

• affects many body systems
• goitre (enlarged thyroid gland)
• depositions of mucopolysaccharides in skin leads to a coarsening of features
• increased fatigue, weight gain, hair loss, dry skin, constipation, nausea, painful and prolonged menstruation, irritability, anxiety, depression, insomnia, increased BP and cholesterol, chills, convulsions

Question 5

What are some oro-facial presentations of hypothyroidism?

What are some dental aspects of hypothyroidism?

Answer 5

• goitre in neck
• thinning of hair/eyebrows
• puffy skin
• macroglossia
• peri-orbital oedema

Dental aspects:

• care with sedation if clinically hypothyroid
• oral candidiasis more common

Question 6

How is hypothyroidism treated?

Answer 6

• replacement of thyroxine (T4)
• life-long therapy
• adequacy of replacement checked with thyroid function tests (TSH) and patient reported response to therapy

Question 7

List some causes of hyperthyroidism:

Answer 7

• Graves disease - autoimmune disease (common in women)
• toxic thyroid nodule
• toxic multinodular goitre
• acute thyroiditis
• drugs - amiodarone

Question 8

List some features of hyperthyroidism:

Answer 8

• many body systems involved
• graves disease can cause problems with eyes
• a goitre or thyroid lumps may be present
• intolerance to heat - hot, sweaty, tremours
• finer hair, eyes buldge, lid lag as orbits push forward
• tachycardia, hypertensive, weight loss, muscle wasting, diarrhoea, menstrual changes

Question 9

List some oro-facial presentations of hyperthyroidism:

Dental aspects?

Answer 9

• graves eye disease
• face flushing
• tremour of hands
• goitre

Dental aspects:

• taste disturbance due to carbizamole and propylthiouracil
• uncontrolled hyperthyroidism is contraindicated to use of adrenaline in LA

Question 10

How is hyperthyroidism treated?

Answer 10

• suppress thyroid hormone: carbizamole, propylthiouracil, beta-blockers to reduce symptoms initially
• radioactive iodine 131
• surgery (less common)