Thyroid Disease in Pregnancy

Question 1

What physiological thyroid change exists?

Answer 1

fall in TSH and rise in free T4 is expected (-> free T4 will then fall with advancing gestation)

Question 2

When do you perform TFTs?

Answer 2

o	Current thyroid disease				
Previous thyroid disease
o	1st degree 
FHx thyroid disease			
AI conditions (Coeliac’s, T1/T2DM, GDM)

Question 3

Summarise Hypothyroidism in pregnancy

Answer 3

thyroxine increased by 25 μg, even if currently euthyroid
• Repeat TFTs in 2 weeks and perform in each trimester to adjust dose if required
• This hopes to mimic the rise in thyroid hormone seen in normal pregnancy
> Continue thyroid replacement therapy throughout pregnancy
• Aim for biochemical euthyroidism (TSH <4 mmol/L)
> Corrected hypothyroidism has no influence on pregnancy outcome or complications
> Suboptimal replacement is associated with developmental delay and pregnancy loss
o Postpartum (Postpartum Thyroiditis / PPT):

Question 4

Summarise post partum hypothyroidism

Answer 4

 Diagnosed based on THREE criteria:
• Patient is ≤12 months after giving birth
• Clinical manifestations are suggestive of hypothyroidism
• Thyroid function tests (TFTs) alone (no need to measure TPO antibodies)
 There are THREE stages:
• (1) Thyrotoxicosis -> (2) Hypothyroidism -> (3) Euthyroid
• High recurrence rate
• TFTs measured every 2 months after thyrotoxic phase
 Thyroid peroxidase antibodies are present in 90%
 Management:
• Thyrotoxic phase: propranolol (anti-thyroid drugs are not used)
• Hypothyroid phase: thyroxine

Question 5

What is the treatment of hyperthyroidism?

Answer 5

 Propylthiouracil (1st trimester)

 Carbimazole (2nd and 3rd trimester)

Question 6

What are the SE of hyperthyroidism treatment in pregnancy?

Answer 6

 Foetal hypothyroidism (from high doses crossing placenta – hence, use low doses)
• 33% of women can actually stop treatment during pregnancy
• Doses usually require readjustment postpartum to prevent relapse
 Agranulocytosis (do regular checks of maternal WCC)
 Radioactive iodine is CONTRAINDICATED (obliterates the foetal thyroid)
o Risks of uncontrolled thyrotoxicosis (explain to mother) -> increased risk of miscarriage, PTL, IUGR
o TSH-receptor stimulating antibodies can cross the placenta, so babies born to women with positive antibody titres should be reviewed by the neonatology team

Question 7

Summarise hyperparathyroidism

Answer 7

o Parathyroidectomy may be indicated for severe cases
o Mild hyperparathyroidism is managed with adequate hydration and low calcium diet
o Risks:
 Increased rates of miscarriage
Intrauterine death
 Preterm labour
Neonatal tetany

Question 8

Summarise Hypoparathyroidism

Answer 8

o Risks:
- Increased risk of 2nd trimester miscarriage
Foetal hypocalcaemia
- Neonatal rickets

o Management:
- Vitamin D
Oral calcium supplements
- Regular monitoring of calcium and albumin