Hypothyroidism

Question 1

What is the definition of hypothyroidism?

Answer 1

Low activity of the thyroid gland

Question 2

How common is hypothyroidism?

Answer 2

Overall UK prevalence of over 2% in woman and under 0.1% in men

Question 3

What is the pathophysiology of hypothyroidism?

Answer 3

• TRH (Thyroid releasing hormone) is produced in the hypothalamus
• = pituitary gland secretes thyroid stimulating hormone (TSH)
• = THS stimulates growth and activity of the thyroid follicular cells
• Inorganic iodine → T3 (active) and T4 (prohormone) is released
• More T4 is produced but converted in peripheral tissue
• T3 binds to specific nuclear receptors on target cells
• Primary: disease of the thyroid
• Secondary: hypothalamic-pituitary disease

Question 4

What are the risk factors/aetiology of hypothyroidism?

Answer 4

• Woman
• Congenital
• Family history
• Autoimmune
• Hashimoto’s thyroiditis – most common in late middle age woman
• Postpartum thyroiditis (after pregnancy)
• Hypopituitarism
• Iodine deficiency
• Dyshormonogenesis – rare. Genetic defect in the synthesis of thyroid hormones
• Anti-thyroid drugs e.g. carbimazole
• Infective thyroiditis e.g. viral (de Quervains)
• Tumour
• Drugs: amiodarone, lithium
• Post-surgery
• Radiation

Question 5

What are the signs/symptoms of hypothyroidism?

Answer 5

• Tiredness
• Bradycardia
• Weight gain
• Cold intolerance
• Cold peripheries
• Goitre
• Depression
• Dry brittle hair and skin
• Loss of outer 1/3 of eyebrows
• ‘Peaches and cream’ appearance
• Muscle weakness
• Carpal tunnel
• Slow reflexed
• Poor libido
• Amenorrhoea
• Constipation
• Periorbital oedema/puffy eyes

Question 6

What diseases present similarly to hypothyroidism?

Answer 6

• Depression
• Anaemia
• Alzheimers dementia

Question 7

What investigations would be conducted if hypothyroidism was suspected?

Answer 7

• TFTs – immunoasssays for free T4, T3 and TSH
• ECG
• FBC for anaemia

Question 8

What is the surgical treatment for hypothyroidism?

Answer 8

Removal of tumour (if that is the cause)

Question 9

What is the pharmacological treatment for hypothyroidism?

Answer 9

Levothyroxine

Question 10

What is the non pharmacological treatment for hypothyroidism?

Answer 10

Non pharmacological • Screening for congenital hypothyroidism