Hypothyroidism

Question 1

What can causes hypothyroidism?

Answer 1

Hashimoto’s thyroiditis (aka chronic lymphocytic thyroiditis) - commonest cause
Iodine deficiency

Question 2

What is the Hashimoto’s thyroiditis?

Answer 2

COMMONEST cause and is autoimmune disease
T cell infiltration -> destruction of thyroid tissue
- Thus causing hypothyroidism
May cause firm goitre in early stages - easily palpable
Has antibodies to TPO (thyroid peroxidase), Tg (thyroglobulin)
Affects mainly WOMEN > men, aged 40+
- 10:1 ratio

Question 3

What does TPO do?

Answer 3

It iodinates tyrosine to form T4

Question 4

What features are seen in hypothyroidism?

Answer 4

• Weight gain
• Lethargy - extremely tired
• Cold intolerance
• Cool dry skin
• Dry brittle hair, nails changes
• Constipation
• Heavy periods (can cause iron-deficiency anaemia)
• Muscle cramps

Question 5

What features have the greatest ability to discriminate between euthyroidism and hypothyroidism?

Answer 5

Myalgia/muscle weakness
Cold intolerance
Constipation
Hoarse/deep voice

Question 6

Why may hypercholesterolaemia be seen in hypothyroidism ?

Answer 6

Due to the rate at which cholesterol is used decreasing

Important to treat hypothyroidism first

Question 7

What do tests show in hypothyroidism?

Answer 7

Primary - T4 LOW, TSH raised
Secondary- T4 LOW, TSH LOW

TSH >2mU/L increases risk of developing hypothyroidism in next 20 years
Positive TPO antibodies increases risk further

Question 8

How is hypothyroidism treated?

Answer 8

Thyroxine (T4) 50-150 micrograms
- Usual to adjust dose in 25 micrograms steps
Once daily dose

Question 9

What side effects may occur with thyroxine (T4)?

Answer 9

Over use can cause AF and osteoporosis

Monitor dose with TFTs