Pregnancy: Thyroid Problems

Question 1

What physiological changes occur in pregnancy regarding Thyroxine-binding globulin and Thyroxine?

Answer 1

TBG levels increase (which causes an increase in the total thyroxine levels) but does not affect the free thyroxine level.

Question 2

What is the most common cause of thyrotoxicosis in pregnancy?

Answer 2

Grave’s disease

Question 3

What is transient gestational hyperthyroidism and what is the path of the disease throughout pregnancy?

Answer 3

When HCG activates the TSH receptor.

As HCG decreases so does the disease. (Usually resolves by the second and third trimester)

Question 4

What are the risks of hyperthyroidism in pregnancy?

Answer 4

Fetal loss, maternal heart failure and premature labour.

Question 5

How is hyperthyroidism managed in pregnancy?

Answer 5

• Propylthiouracil has traditionally been the antithyroid drug of choice. This approach was supported by the 2007 Endocrine Society consensus guidelines
• Maternal free thyroxine levels should be kept in the upper third of the normal reference range to avoid fetal hypothyroidism
• Thyrotrophin receptor stimulating antibodies should be checked at 30-36 weeks gestation - helps to determine risk of neonatal thyroid problems
• Block-and-replace regimes should not be used in pregnancy
• Radioiodine therapy is contraindicated

Question 6

For a hypothyroid pregnant lady, is thyroxine safe to take during pregnancy?

Answer 6

Yes

Question 7

How should a hypothyroid pregnant woman be monitored?

Answer 7

TSH levels measured in each trimester and 6-8 weeks post partum

Question 8

In pregnant women with hypothyroidism, what do they usually require to be done with their levothyroxine?

Answer 8

It usually needs to be increased during pregnancy

Question 9

Is breast feeding safe whilst on thyroxine?

Answer 9

Yes