Hypothyroidism

Question 1

How common is it?

Answer 1

Prevalence of spontaneous hypothyroidism is 1-2%.

Question 2

Who does it affect?

Answer 2

Women 10x more than men

Question 3

What causes it?

Answer 3

Iodine deficiency (most common cause worldwide).

Autoimmune thyroiditis (Such as Hashimotos or atrophic thyroiditis).

Post-ablative therapy or surgery

Drugs: About 15% of people treated with anti-thyroid drugs for Graves’ disease (such as carbimazole) will develop hypothyroidism 10-20 years later. Also: iodine (including kelp supplements), amiodarone, lithium, interferons, thalidomide and rifampicin

Transient thyroiditis:

Subacute thyroiditis (caused by viral infection)

Postpartum thyroiditis (PPT).

Thyroid infiltrative disorders: Such as amyloidosis, sarcoidosis, haemochromatosis, tuberculosis and sclerodermas

Congenital hypothyroidism

Secondary causes: pituitary dysfunction or hypothalamic dysfunction

Question 4

How does it present?

Answer 4

Tiredness/malaise. 
Weight gain. 
Anorexia. 
Cold intolerance. 
Poor memory. 
Change in appearance, 
Depression
Poor libido
Goitre
puffy eyes
muscle weakness/stiffness, 
constipation, 
menorrhagia or oligomenorrhagia, 
psychosis

Question 5

Signs on examination

Answer 5

Mental slowness
Ataxia
Poverty of movement
Peaches and cream complexion
Dry, thin hair
Bradycardia
Loss of outer 1/3/ of eyebrow
Goitre

Question 6

Investigations?

Answer 6

TSH, T4 and thyroid Ab

Question 7

Treatment

Answer 7

Lifelong levothyroxine at a daily dose of 1.6 micro grams/kg daily. Titrated according to thyroid function tests