Thyroid

Question 1

What biochemical changes occur in normal pregnancy?

Answer 1

Mimis hyperthyroidism:
Pulse raised
Warm moist skin
Slight goitre
Anxiety

Thyroid binding globulin and T4 output rise
High levels of hCG mimic TSH (similar structure)
Reduced availability of idoine
TSH may fall in 1st trimester (suppressed by hCG)

Question 2

What is risk fo hyperthyroidism in pregnancy?

Answer 2

Prematurity

EFtal loss

Question 3

What is used to treat hyperthyroidism in pregnancy?

Answer 3

Carbimazole
Propylthiouracil - crosses placenta less
Monitor > monthly
Partial thyroidectomy can be done in 2nd trimester - for dysphagia, stridor, large goitre, suspected carcinoma or antithyroid drug allergy

Question 4

What should you be aware of during labour?

Answer 4

Thyroid storm - fever, t tachycardia, altered mental state, coma

Question 5

What can hypothyroidism cause?

Answer 5

Infertility
Oligomenorrhoea or menorrhagia
Increase rate of miscarriage
Stillbirth
Anaemia
PRe-eclampsia
IUGR

Optimise T4 preconception
Monitor each trimester

Question 6

What are the stages of postpartum thyroiditis?

Answer 6

Thyrotoxicosis
Hypothroidism (4m post-partum)
Normal thyroid function

TFTs to diagnose

90% have thyroid peroxidase antibodies

Question 7

Why do antithyroid drugs not work in postpartum thyroiditis? Mx?

Answer 7

Thyrotoxicosis is from thyroid destruction releasing thyroxine rather than increased synthesis
Propanolol for symptom control

Thyroxine for hypothyroid phase

Question 8

What should you monitor for?

Answer 8

Postpartum depression associated with hypothyroidism