thyroxine

Question 1

What is levothyroxine and liothyronine used for/

Answer 1

• Primary hypothyroidism

- Hypothyroidism secondary to hypopituitarism

Question 2

How does levothyroxine work?

Answer 2

Levothyroxine is synthetitic T4 (has longer action than liothyronine, synthetic T3)

Question 3

What drug is used is reserved for emergency treatment of hypothyroid?

Answer 3

Liothyronine

Question 4

What are the side effects of thyroxine treatment?

Answer 4

Side effects are similar to hyperthyroidism:

• GI upset (diarrhoea , vomiting, weight loss)
• Cardia (palpitations, arrhythmias, angina)
• Neuro (restless, tremor, insomnia)

Question 5

What patient’s should thyroxine be used cautiously with?

Answer 5

• coronary artery disease (because thyroid hormones increase heart rate so can cause cardiac ischaemia)
• Hypopituitarism ( start corticosteroid treatment to avoid causing addison’s)

Question 6

what are the drug interactions of levothyroixine?

Answer 6

GI absorption of levothyroxine is reduced by:
- antacids
-calcium
-iron salts
So give with a 4 hour gap.

• Increased dose of levothyroxine given for patients taking cytochrome P450 inducers (e.g. phenytoin amd carbamezapine)
• increased insulin requirments
• enhances warfarin

Question 7

What is the initial starting dose of levothyroxine and how is it taken?

Answer 7

Levothyroxine intial starting dose is 50 - 100 mg , it is taken orally daily.

Liothyronine can be given IV for emergency

Question 8

how is thyroxine treatment monitored?

Answer 8

• thyroid function test

- TSH levels (primary hypothyroidism) should return to normal due to negative feedback.