Hypothyroidism

Question 1

What are the demographics for hypotyhroidism?

Answer 1

• 2% of the UK population have hypothyroidism
• 5% of people over 60 in the UK
• Most patients are diagnosed between aged 30-60 years old
• Is 10 x more common in women

Question 2

What are the potential causes of hypothyroidism?

Answer 2

• Primary hypothyroidism- failure of the thyroid gland
• Iodine deficiency- iodine is obtained from the diet e.g. from shellfish, salt and fish- however 38% of the world live in iodine deficient areas away from the sea
• As a result of treatment for hyperthyroidism
• use of Amiadorone or lithium
• Hashimoto’s thyroiditis- an autoimmune disease where the body produces antibodies to thyroglobulin and prevents the thyroid hormone from being made
• Pituitary dysfunction- production of TSH is insufficient (secondary hypothyroidism) or low levels of TRH from hypothalamus (tertiary)

Question 3

What can iodine deficiency lead to?

Answer 3

Congenital myxoedema- a congenital condition caused by deficiency of iodine in pre-natal development. This can cause dwarfed stature, mental retardation,
dystrophy of the bones, and a low basal metabolism

Question 4

What are the symptoms of hypothyroidism?

Answer 4

Metabolism is slower so everything is slowed down and weaker
- slow metabolic rate
- constipation
- cold intolerance
- memory loss
- depression
- sparse, thin hair
- bradycardia
- weight gain
- amenhorrea
- dry skin
- fatigue
- fluid retention

Question 5

How is hypothyroidism diagnosed?

Answer 5

By thyroid function tests (TFTs)- take a sample of blood and look at levels of free T3 and T4 and TSH

Question 6

What T3, T4 and TSH levels are inidicative of hypothyroidism?

Answer 6

TSH level is gold standard for diagnosis
- High TSH level
- Low free T3 and T4 levels

due to insufficient T4 and T3 produced by thyroid and resulting
negative feedback causing anterior pituitary to produce more
TSH

Question 7

What should values for T3, T4 and TSH be if a healthy individual?

Answer 7

TSH (0.4-4.5 μIU/mL)
FT4 (10-24 pmol/L )
FT3 (4-7.8 pmol/L)

Question 8

What is the treatment for hypothyroidism?

Answer 8

• Need to replace the thyroxine (T4) hormone by giving oral levothyroxine
  The dose is usually 50-100 mcg, or 25 mcg in the elderly
  this medication can take months to work, expecially in very high TSH levels, so TSH levels are monitored after 2-3 months initially. if still raised the dose can be increased by 25-50 mcg, the max dose usually seen is 200 mcg
• Liothyronine (T3)- Can be given in severe cases e.g. hypothyroid coma as it can be given IV and acts more rapidly However, the duration of action is shorter
• Iodine- will be given if the issue is due to an iodine deficiency

Question 9

What important counselling should be given to a patient starting Levothyroxine and why?

Answer 9

• The medication should be taken in the morning and on an empty stomach.

This is because food can decrease absorption by 40-80%