Thyroid Hormones Flashcards
Give an example of a thyroid hormone?
Levothyroxine
What is the mechanism of action of levothyroxine?
Replaces low level of thyroxine in patients with underachieve thyroid glands, which in turn suppresses high TSH by negative feedback
What are the symptoms of hypothyroidism?
- Lethargy
- Tiredness
- Weight gain
- Thinning of skin and hair
What is an over-replacement of thyroxine characterised by?
Normal thyroxine level with a low TSH level
What is the route of delivery of levothyroxine?
PO
What are the indications for thyroxine?
- Primary hypothyroidism
- As ‘replace’ element of ‘block and replace’ regimen for hyperthyroidism
- Goitre
- Hashimoto’s thyroiditis
- Thyroid carcinoma
- Hypopituitarism
- Pregnancy-related hypothyroidism
What are the contraindications to thyroxine?
Thyrotoxicosis
When should thyroxine be used with caution?
- Long-standing hypothyroidism
- Adrenal insufficiency
- Angina and cardiovascular disorders
What monitoring is required with thyroxine?
- Baseline ECG when starting drug
- TFTs
Why should a baseline ECG be done when starting thyroxine?
For comparison with future ECGs taken if patients develop cardiovascular side-effects from the thyroid hormone replacement
When should TFTs be done with thyroxine?
3 months after starting treatment or changing dose, and annual once stable
When should maternal thyroid function be assessed?
- Before conception
- Diagnosis of pregnancy
- During 2nd and 3rd trimester
- After delivery
What might need to happen to levothyroxine dose during pregnancy?
May need to be increased
What needs to be done if thyroxine dose is changed during pregnancy?
Increased monitoring of thyroid function
What should be considered with long-term treatment with thyroxine?
Consider supplementation with vitamin D