Thyroid Disorders in Pregnancy Flashcards
case 2 has evident hyperthyroidism, but TSH is pretty low in the case 1 as well, indicating that it might have a subclinical picture
clinical features of hyperthyroidism common to pregnancy
- heat intolerance
- tachycardia
- wide pulse pressure
- flow murmur
- radiant heat from hands
- goiter– in iodine deficient areas
Changes in thyroid physilogy in pregnancy:
- HCG stimulates ___ receptor
- HCG peaks at end of ___ trimester
- 20% of pregnant women have TSH below nonppregnant TSH reference range from 8-14 weeks gestation, but free T4 and T3 is normal.
- HCG stimulates TSH receptor
- HCG peaks at end of 1st trimester
- 20% of pregnant women TSH below nonppregnant TSH reference range from 8-14 weeks gestation, but free T4 and T3 is normal.
how does TSH level and free T4 levels change during pregnancy
TSH: first trimester: reduced TSH at 7-14 weeks), then it rreturns to baseline in third trimester.
- free T4 decreases is in the second and third trimesters
3) 20% pregnant women TSH below nonpregnant TSH
reference range from 8-14 wks gestation but Free T4 and
Free T3 normal
outline how TSH levels normal range change depending on gestational weeks
in pregnancy, thyroid binding globulin concentration ____. Why?
increases by 2-3 times. Estrogens stimulate expression of TBG in liver, and the normal rise in estrogen during pregnancy induces roughly a doubling in serum TBG concentratrations.
General outline when first thinking about thyroid issues in pregnancy
- check for goiter
- use gestational age specific TSH reference range
- look at free Y4 and T3
- clinical follow up and repeat TSH 4 weeks later.
most common etiology of hyperthyroidism in pregnancy
85-90% of casese of hyperthyroidism in pregnancy is Graves disease
- other etiologies include toxic MN goiter, subacute thyroiditis, toxic adenoma, gestational trophoblastic disease
causes of Transient Hyperthyroxinemia of Pregnancy
hyperthyroidism and pregnancy general diagnosis
decreased TSH
increased free T4, free t3,
goiter
5 risks of untreated hyperthyroidism in pregnancy
- miscarriage
- preterm delivery
- lpw bith weight
- pre-exlampsia
- thyroid storm
T/f the first step of manageing hyperthyroidism in pregnancy is radioiodine
false. radioiodine is contraindicated
Which antithyroid medication is preferred to use in hypertension of pregnancy? compare the two most common classes
Propylthiouracil (PTU) preferred over Methimazole (<16
weeks gestation)
outline the birthdefects seen in the use of methimazole anti-thyroid meds (Methimazole Embryopathy)
choanal atresia common
general management of hyperthyroidism in pregnancy if you can’t use radioiodine
4) Render pt euthyroid with low dose antithyroid
medication (PTU preferred until 16 wks gestation)
•
5) Monitor TSH, Free T4 every 1 to 4 wks to titrate
antithyroid medication
• 6)Keep Maternal freeT4 high trimester specific normal
note
t/f anti-thyroid drugs are safe for breastfeeding
true
true false: radioiodine remains contraindicated of breasfeeding
true
t/f post partum relapse of hyperthryoidism is common
true
if someone is hyperthyroid before conception, what should you do?
fix prior to pregnancy! use I131 plus 6 month contraception while fixing it. consider surgery
note; this demonstrates that PTU is safer than MMZ as an antithyroid drug because it is less liekly to go to the fetus. it also shows the iodine is contraindicated because it fully goes to the fetus
outline the relationship between maternal Graves disease and fetal risk of hyperthyroidism
the rate is 1-3%.
- if the TSH receptor antibodies are over 8 times greater than normal, it predicts higher risk for fetal/neonatal hyperthyroidism
lab values for OVERT HYPOthyroidism in pregnanyc
TSH >10mU/L
low free T4
Women at risk for hypothyroidism in pregnancy
- ones with overt hypothyroidism
- women on thyroid replacement
- not women with minor TSH elevatois (subclinical hypothyroidism)
consequences of untreated overt maternal hypothyroidism
- fetal loss
- hypertension
3 .placental abruption
- post partum hemorrahe
- impaired neurodevelopment in child in overt hypothyroidism
Changes in Thyroid Physiology in Pregnancy
• __ __ __ (TBG) increases
• 20 - 40% __ in maternal __ production required to
saturated the increase binding sites
Changes in Thyroid Physiology in Pregnancy
• Thyroid binding globulin (TBG) increases
• 20 - 40% increase in maternal T4 production required to
saturated the increase binding sites
- *Reminders for Childbearing age women on thyroid replacement**
1) Separate L __ from __ or __ by at least 2 hours
2) Preconception:
• TSH < 1.2 mIU/L monitor ___
• TSH >1.2 mIU/L __ by ___ tablet/wk once pregnant
3) when Postpartum return to prepregnancy dose
- *Reminders for Childbearing age women on thyroid replacement**
1) Separate L thyroxine from iron or calcium by at least 2 hours
2) Preconception
• TSH < 1.2 mIU/L monitor TSH
• TSH >1.2 mIU/L Increase by 2 tablet/wk once pregnant
3) Postpartum return to prepregnancy dose
How frequently do you monitor TSH in pregnancy and after
<20 weeks; q 4 weeks until stable then:
Q trimester (once a trimester)
6-8 weeks postpartum
Thyroid Supplementation During Pregnancy
• Who to treat?
Women on Thyroid Replacement Preconception need
monitoring +/- dosage adjustment to avoid overt hypothyroidism in pregnancy
OR
• TSH > 10mU/L discovered in pregnancy
T/F You should give thyroid supplementation fo those with TSH<5 in pregnancy
false.
Who not to treat?
• TSH < 5mU/L discovered in pregnancy
• Normal TSH with positive antibodies
T/F you should treat women with anti-thyroid antibodies but normal TSH in pregnancy
false
Who not to treat?
• TSH < 5mU/L discovered in pregnancy
• Normal TSH with positive antibodies
If you give too much thyroid supplementation,it can cause TSH suppression which is also bad. Who is at risk of TSH suppression?
Post hoc analysis to explore factors associated with TSH suppression <0.1. mIU/L during pregnancy
1) preconception TSH <1.50mIU/L
2) levothyroxine dose greater than 100 mcg/day
how do TSH levels change in pregnancy?
in the first trimester, TSH decreases, and then return back to normal in the second and third trimesters
Outline the scheme of TSH management/checking in pregnancy in a patient with NO HISTORY OF THYROID DYSFUCNTION
T/F babies born to mothers with subclinical hypothyroidism have been shown to have reduced IQ
false. even when thyroxine was started, there was no difference.
T/F: giving Levothyroxine preconception for women with Positive Thyroid Antibodies have been shown to improve pregnancy outcomes
false.
note: key messages about thyroid replacement in pregnancy
That is the Etiology of her Hyperthyroid State?
A) Graves’ Disease B) Postpartum thyroiditis C) Toxic thyroid adenoma D) All of the above
could be anything but graves is the most common
Post partum thyroiditis:
5-10% of women postpartum get thyroiditis
- women with ____ are 25% more likely
TYPE 1 DM
Etiologies of post partum thyroiditis
Etiology
• immune mediated
• thyroid antibodies
• lymphocytic infiltration
• destructive thyroiditis
Clinical features of thyroid gland is woman with PPThyroiditis? painful? enlarged? soft or firm?
NON painful NON tender
slightly enlarged
firm
natural history of post partum thyroiditis
- Transient Hyperthyroidism 2-4 months postpartum
- Resolution
- Hypothyroidism 5-8 months postpartum
- Hypothyroidism permanent - 25%
• 70% recurrence in subsequent pregnancy
• 50% permanent hypothyroidism in 7 years
ESR, TSG, I131 levels in someone with post partum thyroiditis
ESR; normal
TSH; increasd, normal, decreased lol could be anything
I131 : decreased uptake because they are releasing their contents
post partum thyroiditis management in the hyperthyroid phase
SO NOT GIVE ANTITHYROID MEDS, but consider beta blockers
post partum thyroiditis management of the hypothyroid phase
consider low dose thyroxine replacement, low dose and under a 1 year duration
T/F: it is good to use desiccated thyroid (med with T4 and T3) during management of hypothyroidism in pregnancy
FALSE. AVOID ANY t3 contianing preparation during pregnancy.
