Hypothyroidism - booklet

Question 1

Common cause primary hypothyroidism

Answer 1

1. Autoimmune disease - Hashimotos
2. Pregnancy
3. Iodine deficiency - developing countries
4. Genetic defect - familial thyroid dyshormonogenesis
5. Drugs - amiodarone, lithium
6. Iatrogenic - treatment of hyperthyroidism
7. Radiation to head and neck

Question 2

Secondary hypothyroidism

Answer 2

• TSH deficiency
• Hypothalamic pituitary disease
• Low T4 and non elevated TSH

Question 3

Features of hypothyroidism

Answer 3

• Weight gain
• Cold intolerance
• Fatigue
• Constipation
• Bradycardia
• Thickening skin and puffiness around eyes (myxoedema)

Question 4

What are symptoms of hypothyroidism similar to?

Answer 4

Depression - more common, if slight deranged TFTs could not be this that’s causing mood problems

Question 5

Inv hypothyroidism

Answer 5

• Low T4 elevated TSH
• TPO - thyroid peroxidase antibodies are strong positive in Hashimotos

Question 6

Treatment of hypothyroidism

Answer 6

• Thyroxine replacement
• 500-100 ug /day
• Eldery or ischaemic heart disease = lower dose
• If TSH persisently elevated then dose is not enough, poor compliance or malabsoprtion

Question 7

Causes of malabsorption resulting in thyroxine dose not suppressing TSH

Answer 7

• Coeliac
• Concurrent medication eg iron, calcium or PPIs

Question 8

What does suppressed/undectable TSH show?

Answer 8

• Over replacement
• Increase risk of a-fib and osteoporosis

Question 9

What is subclinical hypothyroidism?

Answer 9

Normal T4 with elevated TSH

Question 10

Treatment subclinical hypothyroidism

Answer 10

• If asymptomatic - may need no treatment
• Can revert back to normal in 10-15%

Question 11

When should you treat subclinical hypothyroidism?

Answer 11

• If TSH is more than 10miU/L even if asymptomatic due to high likelihood of progression to frank hypothyroidism
• Also consider in women planning pregnancy if is 5-10, symptomatic patients and pts with significant dyslipidaemia