Thyroid_Pregnancy

Question 1

Why does pregnancy requires 30-50% increase in thyroid hormone secretion (ref mja article)

Answer 1

HCG stimulates the thyroid gland
increases thyroxine binding globulin
degrades thyroid hormone by the placenta
(ref: MJA)

Question 2

How would you manage a woman with hypothyroidism that is planning a preganancy?

Answer 2

Aim serum TSH in the lower reference range (0.4-2.5 mU/L).
When pregnancy is confirmed → increase thyroxine dosage by about 30% conveniently achieved by doubling the thyroxine dose on 2 days per week (with no change on other days).
Check Serum TSH every 4-6 weeks until 20 weeks’ gestation, then once in the third trimester.
After delivery, thyroxine dosage can be reduced to pre-pregnancy levels and TSH levels checked at 6-8 weeks postpartum
(MJA)