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A tweetorial on hyperthyroidism during pregnancy.
Following yesterday's @ObsMedEd webinar on thyroid disease in pregnancy:
#MedTwitter #FirstTweetorial
Feedback and discussion more than welcome!
[Picture: neonatal Graves' disease] https://www.nejm.org/doi/full/10.1056/NEJMicm1308956
![A tweetorial on hyperthyroidism during pregnancy.Following yesterday's @ObsMedEd webinar on thyroid disease in pregnancy: #MedTwitter #FirstTweetorialFeedback and discussion more than welcome![Picture: neonatal Graves' disease] https://www.nejm.org/doi/full/10.1056/NEJMicm1308956](https://pbs.twimg.com/media/EasyIvKXQAIQN5N.png "A tweetorial on hyperthyroidism during pregnancy.Following yesterday's @ObsMedEd webinar on thyroid disease in pregnancy: #MedTwitter #FirstTweetorialFeedback and discussion more than welcome![Picture: neonatal Graves' disease] https://www.nejm.org/doi/full/10.1056/NEJMicm1308956")
Following yesterday's @ObsMedEd webinar on thyroid disease in pregnancy:
#MedTwitter #FirstTweetorial
Feedback and discussion more than welcome!
[Picture: neonatal Graves' disease] https://www.nejm.org/doi/full/10.1056/NEJMicm1308956
Hyperthyroidism occurs in 1%-2.2% of pregnancies, depending on the reference range you use.
Probably 95% of hyperthyroidism in pregnancy is physiological due to thyroid stimulation by hCG.
https://www.liebertpub.com/doi/abs/10.1089/thy.2018.0475
https://academic.oup.com/clinchem/article/61/5/704/5611406
Figure from http://rdcu.be/uKOO
Probably 95% of hyperthyroidism in pregnancy is physiological due to thyroid stimulation by hCG.
https://www.liebertpub.com/doi/abs/10.1089/thy.2018.0475
https://academic.oup.com/clinchem/article/61/5/704/5611406
Figure from http://rdcu.be/uKOO
hCG --> high structural similarity with TSH --> weak binding affinity for TSH receptor (TSHr)
--> ~50% increase thyroid hormone production/secretion in pregnancy
--> negative feedback --> lower TSH --> (subclinical) hyperthyroidism
--> ~50% increase thyroid hormone production/secretion in pregnancy
--> negative feedback --> lower TSH --> (subclinical) hyperthyroidism
Physiological or hCG-mediated hyperthyroidism should be distinguished from pathophysiological hyperthyroidism.
Physiological: similar risk or even protective of adverse pregnancy outcomes
Pathophysiological: higher risk of adverse pregnancy outcomes.
Physiological: similar risk or even protective of adverse pregnancy outcomes
Pathophysiological: higher risk of adverse pregnancy outcomes.
Let's look at the differential diagnosis.
First thing to distinguish is Graves' disease.
Risk factors: clinical signs, FT4 >1.5x ULN, persisting hyperthyroidism after week 18.
First thing to distinguish is Graves' disease.
Risk factors: clinical signs, FT4 >1.5x ULN, persisting hyperthyroidism after week 18.
Graves' disease complicates 0.5% of pregnancies.
--> 90% have pre-existing disease - newly diagnosed is very rare!
Higher risk of various pregnancy complications, especially if biochemically uncontrolled.
Thus, preconception counselling is pivotal!
https://pubmed.ncbi.nlm.nih.gov/24481256/
--> 90% have pre-existing disease - newly diagnosed is very rare!
Higher risk of various pregnancy complications, especially if biochemically uncontrolled.
Thus, preconception counselling is pivotal!
https://pubmed.ncbi.nlm.nih.gov/24481256/
In any woman <45 yrs diagnosed with Graves' disease, discuss:
Antconception
Pregnancy planning
Contacting you upon a positive pregnancy test
Treatment options [see very basic info below]
![In any woman <45 yrs diagnosed with Graves' disease, discuss:AntconceptionPregnancy planningContacting you upon a positive pregnancy testTreatment options [see very basic info below]](https://pbs.twimg.com/media/Eas_S_6XkAMixaj.png "In any woman <45 yrs diagnosed with Graves' disease, discuss:AntconceptionPregnancy planningContacting you upon a positive pregnancy testTreatment options [see very basic info below]")
Antconception
Pregnancy planning
Contacting you upon a positive pregnancy test
Treatment options [see very basic info below]
Besides the hard contraindication for conception within 6 months after radioactive iodine due to radioactivity, there is also a relative contraindication for ~18 months due to a flare in TSHr antibodies.
To measure = to know, though.
https://eje.bioscientifica.com/view/journals/eje/158/1/69.xml
To measure = to know, though.
https://eje.bioscientifica.com/view/journals/eje/158/1/69.xml
So, why not treat all women with antithyroid drugs (ATD) before or during pregnancy?
Recent data indicates a higher risk of fetal birth defects.
Absolute risk increase is 3% [PTU] to 5% [MMI].
i.e. 1:20 - 1:33
https://academic.oup.com/jcem/article/98/11/4373/2834832
https://pubmed.ncbi.nlm.nih.gov/29357398/
![So, why not treat all women with antithyroid drugs (ATD) before or during pregnancy?Recent data indicates a higher risk of fetal birth defects.Absolute risk increase is 3% [PTU] to 5% [MMI].i.e. 1:20 - 1:33 https://academic.oup.com/jcem/article/98/11/4373/2834832 https://pubmed.ncbi.nlm.nih.gov/29357398/](https://pbs.twimg.com/media/EatCEifX0AY07qr.jpg "So, why not treat all women with antithyroid drugs (ATD) before or during pregnancy?Recent data indicates a higher risk of fetal birth defects.Absolute risk increase is 3% [PTU] to 5% [MMI].i.e. 1:20 - 1:33 https://academic.oup.com/jcem/article/98/11/4373/2834832 https://pubmed.ncbi.nlm.nih.gov/29357398/")
Recent data indicates a higher risk of fetal birth defects.
Absolute risk increase is 3% [PTU] to 5% [MMI].
i.e. 1:20 - 1:33
https://academic.oup.com/jcem/article/98/11/4373/2834832
https://pubmed.ncbi.nlm.nih.gov/29357398/
Mind that any choice has pros & cons.
If ATD required, PTU is preferred
-Lower overall risk
-Less severe fetal birth defects
-No dose-dependent risks [see 2nd link above)
https://rdcu.be/LS6f
In addition, be aware of fetal hypothyroidism [placental passage, see below]
![Mind that any choice has pros & cons.If ATD required, PTU is preferred-Lower overall risk-Less severe fetal birth defects-No dose-dependent risks [see 2nd link above) https://rdcu.be/LS6f In addition, be aware of fetal hypothyroidism [placental passage, see below]](https://pbs.twimg.com/media/EatOTl-XsAEd3gx.png "Mind that any choice has pros & cons.If ATD required, PTU is preferred-Lower overall risk-Less severe fetal birth defects-No dose-dependent risks [see 2nd link above) https://rdcu.be/LS6f In addition, be aware of fetal hypothyroidism [placental passage, see below]")
If ATD required, PTU is preferred
-Lower overall risk
-Less severe fetal birth defects
-No dose-dependent risks [see 2nd link above)
https://rdcu.be/LS6f
In addition, be aware of fetal hypothyroidism [placental passage, see below]
For any ATD, reducing the exposure around pregnancy will reduce the potential risks.
- Never use block & replace, always titrate
- Consider to stop ATD upon conception --> median time to relapse ~3 months, longer if mild disease
https://www.liebertpub.com/doi/full/10.1089/thy.2016.0457
https://academic.oup.com/jcem/article/101/4/1381/2804501
- Never use block & replace, always titrate
- Consider to stop ATD upon conception --> median time to relapse ~3 months, longer if mild disease
https://www.liebertpub.com/doi/full/10.1089/thy.2016.0457
https://academic.oup.com/jcem/article/101/4/1381/2804501
Monitor disease activity/treatment:
-Check TSH/FT4 every 4-6 weeks
-> maternal tft=fetal tft
-> Immunetolerance -> lower TRAb in 2nd & 3rd trimester -> often ATD dose reduction required
- Fetal ultrasound every 4 weeks after week 18 (=time of fetal thyroid functional maturity)
-Check TSH/FT4 every 4-6 weeks
-> maternal tft=fetal tft
-> Immunetolerance -> lower TRAb in 2nd & 3rd trimester -> often ATD dose reduction required
- Fetal ultrasound every 4 weeks after week 18 (=time of fetal thyroid functional maturity)
Risk assessment of neonatal Graves':
TRAb in early pregnancy
- Negligible risk if <3x ULN, no need to repeat
- If >3x ULN recheck at 25 and 36 weeks
+ intensify ultrasound monitoring
Recheck TRAb if biochemical/ultrasound deterioration.
https://pubmed.ncbi.nlm.nih.gov/29325496/
Next: some pearls!
TRAb in early pregnancy
- Negligible risk if <3x ULN, no need to repeat
- If >3x ULN recheck at 25 and 36 weeks
+ intensify ultrasound monitoring
Recheck TRAb if biochemical/ultrasound deterioration.
https://pubmed.ncbi.nlm.nih.gov/29325496/
Next: some pearls!
Combined stimulating/blocking TRAb can occur, fetal hypOthyroidism in TRAb+ women is possible.
If maternal TFTs/TRAb do not fit with fetal (hyperthyroidism) state, seek expert consultation (amniocentesis?).
Also, TRAb can persist after thyroidectomy!
https://www.acpjournals.org/doi/10.7326/L19-0818
If maternal TFTs/TRAb do not fit with fetal (hyperthyroidism) state, seek expert consultation (amniocentesis?).
Also, TRAb can persist after thyroidectomy!
https://www.acpjournals.org/doi/10.7326/L19-0818
How about the rest of the differential?
Autonomous nodules/multinodular goiter
-> treatment depends on severity and persistence of hyperthyroidism -> mostly mild [below]
Be aware: prior risk of nodule on ultrasound ~25%
Gestational pertechnate scanning possible if necessary.
![How about the rest of the differential?Autonomous nodules/multinodular goiter-> treatment depends on severity and persistence of hyperthyroidism -> mostly mild [below]Be aware: prior risk of nodule on ultrasound ~25%Gestational pertechnate scanning possible if necessary.](https://pbs.twimg.com/media/EatSw-7XYAIZvKQ.png "How about the rest of the differential?Autonomous nodules/multinodular goiter-> treatment depends on severity and persistence of hyperthyroidism -> mostly mild [below]Be aware: prior risk of nodule on ultrasound ~25%Gestational pertechnate scanning possible if necessary.")
Autonomous nodules/multinodular goiter
-> treatment depends on severity and persistence of hyperthyroidism -> mostly mild [below]
Be aware: prior risk of nodule on ultrasound ~25%
Gestational pertechnate scanning possible if necessary.
Subactue thyroiditis is very rare during pregnancy.
Similar to nodular disease, treatment depends on severity and persistence of hyperthyroidism.
Similar to nodular disease, treatment depends on severity and persistence of hyperthyroidism.
Finally: biotine use (vitamin B7)
Found in hair & nail growth vitamin supplements, used in pregnancy also.
Interference in thyroid assays occurs at dosages >2-3mg per day -> biochemically mimics Graves' hyperthyroidism
https://www.nejm.org/doi/full/10.1056/NEJMc1602096 https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2601421
Found in hair & nail growth vitamin supplements, used in pregnancy also.
Interference in thyroid assays occurs at dosages >2-3mg per day -> biochemically mimics Graves' hyperthyroidism
https://www.nejm.org/doi/full/10.1056/NEJMc1602096 https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2601421
Summary:
Hyperthyroidism in pregnancy
-Mostly hCG-mediated and benign.
-Think Graves' (clinical signs, FT4>1.5x ULN, persisting hyperthyroidism).
-Balance treatment pros and cons.
-PTU is preferred ATD.
-Monitor TFTs and fetus.
-Nodules/subactue thyroiditis, think severity.
Hyperthyroidism in pregnancy
-Mostly hCG-mediated and benign.
-Think Graves' (clinical signs, FT4>1.5x ULN, persisting hyperthyroidism).
-Balance treatment pros and cons.
-PTU is preferred ATD.
-Monitor TFTs and fetus.
-Nodules/subactue thyroiditis, think severity.
Was this helpful and would you appreciate a tweetorial on subclinical hypothyroidism in pregnancy as a follow-up?
[Any other suggestions or comments more than welcome]
[Join our research efforts https://www.consortiumthyroidpregnancy.org/ ]
[Any other suggestions or comments more than welcome]
[Join our research efforts https://www.consortiumthyroidpregnancy.org/ ]
