Bela
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If a female suffering from hypothyroidism becomes pregnant, what should the physician do with her Levothyroxine tx?
a) Increase it
b) Decrease it
c) Keep it the same
Why? Explanation behind it, please. 
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| AAAAA
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Actually you should check the TSH level first !
I do not agree with the choices !
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| AAAAA
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What are the normal changes in thyroid function associated with pregnancy?
Hormone Changes. A normal pregnancy results in a number of important changes that alter thyroid function. While usually normal, the TSH may be slightly low in the first trimester
due to high hCG levels (the hormone measured in the pregnancy test) and then return to normal throughout the duration of pregnancy. Increased total T4 is often seen due to an increase in serum binding proteins caused by estrogen. However, measurements of “Free” (or active) hormone remain normal. The thyroid is functioning normally if the TSH, Free T4 and Free T3 are all normal throughout pregnancy.
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| AAAAA
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I had this question in the USMLE but they ask what is the hormone that alter the thyroid hormone.
The answer is high hCG levels !!
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| AAAAA
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In exam, I think they want you to increase the dose of thyroxin !
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| AAAAA
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In real life, you should check the TSH !
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Hypothyroidism in Pregnancy
Maternal hypothyroidism occurs in about 2.5% of all pregnancies and has long been known to be a cause of such adverse pregnancy outcomes as pre-eclampsia, early miscarriage, placental abruption, preterm birth, and stillbirth. Fortunately, treatment with L-thyroxine reduces these complications substantially (1).
More recently, maternal hypothyroidism during early pregnancy has been confirmed as a cause of childhood cognitive defects including reduced IQ scores and other measurements of intelligence, aptitude, and visual motor skills (2, 3). This likely relates to growing evidence that development of a normal fetal brain requires exposure to critically adequate amounts thyroid hormone during the first trimester when the fetus is totally dependent upon maternal thyroxine (4). Although the adverse intellectual outcomes were initially reported only in mothers with overt hypothyroidism (high TSH and low free T4), there now are several reports of similar findings in the setting of subclinical hypothyroidism (high TSH, normal free T4) as well (5-7).
The performance of universal screening for hypothyroidism in early pregnancy is controversial. The prevailing opinion, summarized in the most recent ACOG Guidelines is that there are insufficient data to warrant routine screening of asymptomatic pregnant women for hypothyroidism". Nevertheless, there is widespread support for the evaluation of thyroid function in pregnant women with known hypothyroidism or who are at high-risk for developing hypothyroidism (e.g., patients with type 1 diabetes and/or other non-thyroidal autoimmune disorders, first degree relatives with a history of thyroid autoimmunity such as Graves disease or Hashimotos thyroiditis, or symptoms of hypothyroidism) (8,9).
Pre-conception screening would be the best way to assure that most of these women would be euthyroid at the time of conception. Unfortunately, this approach has proved to be largely impractical. Instead, most current protocols focus on the evaluation and initiation of thyroid treatment as soon after conception as possible. Since thyroid hormone requirements generally increase during pregnancy, these protocols include clear treatment targets as well as strategies for continuous thyroid management throughout pregnancy and into the postpartum period. The recommended TSH target range during pregnancy, the management of pregnant women with established hypothyroidism, and the management of women at high risk for developing hypothyroidism are discussed below.
General Recommendation
Consider having pregnant patients with hypothyroidism followed by an endocrinologist throughout their pregnancy.
Recommended TSH Target Range
TSH target range = 0.3-2.5 mIU/L. The TSH target range for those who are pregnant or wishing to become pregnant represents the lower half of the lab normal range. (10) (Note: TSH values later during the first and early second trimester are often below this range because of physiologic increases in thyroxine production in early pregnancy).
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| AAAAA
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Since thyroid hormone requirements generally increase during pregnancy, these protocols include clear treatment targets as well as strategies for continuous thyroid management throughout pregnancy and into the postpartum period.
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| AAAAA
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You may need to increase the thyroxine to adjust the TSH to the low normal range at least in the first trimester.
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| AAAAA
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Management of Women with Established Hypothyroidism
1) Pre-conception TSH level and patient education regarding the fetal risks of maternal hypothyroidism.
2) TSH level soon after obtaining a positive pregnancy test.
a. If TSH level is in the target range, instruct patient to increase their current thyroxine dose by two extra doses per week (approximately 30%) (11).
b.If TSH level is above the target range, increase daily thyroxine dose by at least 30% and recheck TSH in 4 weeks.
3) Remind the patient to take thyroxine 1 hour before or 2 hours after food or other medications especially prenatal vitamins, iron, and calcium supplements!
4) Monitor TSH level every 1-2 months, adjusting the thyroxine dose to maintain TSH level within target range until delivery.
5) Following delivery, resume thyroxine dose taken prior to pregnancy and recheck TSH level in 4-6 weeks.
Management of Women at High Risk for Developing Hypothyroidism
1) Routine TSH screening of high-risk patients following a positive pregnancy test should be considered.
2) Patients with TSH level above 5.0 mIU/L should be managed as above.
3) There is a lack of consensus regarding the appropriate management of newly pregnant patients with TSH level between 2.5 and 5.0 mIU/L. Treatment decisions should be left to the physician in consultation with the patient.
References
1. Montoro MN. Management of hypothyroidism during pregnancy. Clin Obstet Gynecol 1997; 40:65-80.
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| AAAAA
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To be exact, if the patient TSH is normal, advise the patient to take two extra pills of thyroxine each week !! Increase the thyroxine by 30% during first trimester !!
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| AAAAA
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If the TSH is high, then increase the throxine level on a "daily dose" by 30%.
(I am going to charge consultation fee for your question" Just kidding !)
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| AAAAA
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. If TSH level is in the target range, instruct patient to increase their current thyroxine dose by two extra doses per week (approximately 30%) (11).
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If TSH level is above the target range, increase daily thyroxine dose by at least 30% and recheck TSH in 4 weeks.
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Remind the patient to take thyroxine 1 hour before or 2 hours after food or other medications especially prenatal vitamins, iron, and calcium supplements!
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| AAAAA
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Monitor TSH level every 1-2 months, adjusting the thyroxine dose to maintain TSH level within target range until delivery.
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Following delivery, resume thyroxine dose taken prior to pregnancy and recheck TSH level in 4-6 weeks.
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| AAAAA
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Management of Women at High Risk for Developing Hypothyroidism
1) Routine TSH screening of high-risk patients following a positive pregnancy test should be considered.
2) Patients with TSH level above 5.0 mIU/L should be managed as above.
3) There is a lack of consensus regarding the appropriate management of newly pregnant patients with TSH level between 2.5 and 5.0 mIU/L. Treatment decisions should be left to the physician in consultation with the patient.
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