thyroid disease in pregnancy

Question 1

what is normal TSH in 1st trimester

Answer 1

1st trimester: TSH 0.1 - 2.5
2nd trimester: TSH 0.2 - 3.0
3rd trimester: TSH 0.3 - 3.0

Question 2

indication of TSH in pregnancy (personal 7/obstetrical indication 3)

Answer 2

1. C/F of thyroid disease
2. history or family history of thyroid disease
3. age >30
4. BMI >30
5. T1DM
6. history of neck radiation
7. on Amiodarone or Li+

Obstetric indication

1. > P2
2. recurrent miscarriages
3. previous preterm delivery

Question 3

Why investigate of thyroid disease in pregnancy (complication)? 2

Answer 3

1. increase risk of miscarriage

2. increase risk of premature delivery

Question 4

Hypothyroidism before pregnancy/find her pregnant, what to do?

Answer 4

• if not on thyroxin –> commence thyroxine 50mcg daily
• if on thyroxine –> increase dose by 30-50%
• aim TSH < 2.5

Question 5

hyperthyroidism and planning to be pregnant, what to do?

Answer 5

• if on carbimazole –> consider switch to PTU
• consider stop B-Bloker
• if on radioactive iodine ablation therapy, no pregnancy for 6months
• if partner on radioactive iodine therapy, no conception for 4 months (to consider new sperm cycle)

Question 6

hyperthyroidism and you find her pregnant, what to do?

Answer 6

• stop B-blocker
• if on carbimazole, stop
• prefer for PTU 200-600mg/day in 2-3 doses
• no for radioactive iodine treatment
• can consider surgery

Question 7

low TSH (hyperthyroid) in 1st trimester

Answer 7

most likely gestational hyperthyroidism

• due to increased BhCG
• strong association with hyperemesis gravidarum
• still need workout to rule out other causes of hyperthyroidism

a. Subclinical hyperthyroidism- repeat TSH in 6 weeks

b. Overt hyperthyroidism - as non pregnant
1. TRAB +ve: graves
2. TPO +ve: subacute thyroiditis
3. TPO -ve: cannot do nuclear medicine –> refer to specialist

Question 8

TSH >2.5 (hypothyroidism) in 1st trimester

Answer 8

treat with thyroxine immediately

approach for hypothyroidism

1. subclinical hypothyroidism
2. overt hypothyroidism
   
   • TPO +ve –> hashimoto’s thyroiditis
   • TPO -ve –> iodine deficiency, thyroidectomy, drug induced hypothyroidism

Question 9

hypothyroidism - postpartum thyroiditis - management (4)

Answer 9

Painless

• check anti-TPO (antithyroid peroxidase)
• commence thyroxin 50mcg PO daily
• check TSH in 6 weeks
• explain long term (not life long) treatment might be required.

Question 10

hyperthyroidism - postpartum thyroiditis management (4)

Answer 10

NEED to differentiate from GRAVE’s

• TPO +ve –> postpartum thyroiditis
• TRAB +ve –> grave’s disease
• TPO -ve –> RAIU scan
• Propranolol 10mg daily
• no need PTU and carbimazole if postpartum thyroiditis

Question 11

DDx of postpartum tiredness (8)

Answer 11

1. thyroid disease
2. DM
3. postnatal depression
4. iron deficiency anaemia
5. burn out
6. sleep deprivation
7. substance abuse
8. pregnancy