thyroid disease in pregnancy

Question 1

who to screen for thyroid disease in pregnancy?

Answer 1

• suspicion for thyroid dz based on sx
• DM I
• family or personal Hx

Question 2

if concerned for hypothyroidism, what tests to order?

Answer 2

TSH, if low then fT4

Question 3

most common etiology of hyperthyroidism?

Answer 3

graves (autoimmune) - 95%

Question 4

how do you treat hyperthyroidism?

Answer 4

• ptu in first trimester. 100 mg TID start (100-600 mg dividied in 2-3 doses)
• methimazole in 2nd and third trimester. start 20 mg daily (5-30 mg divided in 2 doses)
• propanolol for hyperdynamic symtpoms

Question 5

what factors do you consider with treatment of hyperthyroidism?

Answer 5

• tx response hx
• what trimster?
• primarily T4 or T3 thyrotoxicosis

Question 6

what are risks of PTU and methimazole?

Answer 6

• PTU: maternal liver disease, death
• methimazole: esophageal and choanal atresia, aplasia cutis

Both: maternal agranulocytosis

Question 7

surveillance plan for hyper and hypothyroidism:

Answer 7

• hyperthyroidism: free T4 q2-4 weeks (if prior fT3 toxicosis then use this as well)
• hypothyroidism: TSH q4-6 weeks (goal between lower limit of reference range at 2.5 milliU/L)

Question 8

how common and how is postpartum thyroiditis?

Answer 8

5-10% of all pregnancies
transient autoimmune thyroiditis – in first 12 months
typically first hyperthyroid then hypothyroid
supportive therapy for hyperthryoid; hypothyroid offer treatment with levothyroxine

Question 9

treatment of thyroid storm

Answer 9

1% of all graves disease

• PTU (1000 mg PO -> 200 mg q6hr)
• sodium iodine (500 mg -1000 mg IV q8hrs), potassium iodine (5 drops PO q8hr), lugol’s iodine (10 drops q8hr), if hx of iodine anaphylaxis lithium carbonate (300 mg q6hr)
• dexamethasone 2 mg IV q6hr x 4 doses or hydrocortisone 100 mg q8hr x 3 doses
• beta blocker for symptom control (ex: propanolol 20 mg - 80 mg IV)
• supportive measures (benzo PRN, temp control, IVF hydration)

Question 10

describe normal thyroid function/indices in pregnancy

Answer 10

• hcg cross stimulation initially causes decreased tsh
• thyroid volume increases 30% by end of pregnancy
• estrogen causes increase in TBG, and increase in total T4 and T3
• fT3 and fT4 are unchanged though