Hypothyroidism in Late Pregnancy: Key Concerns and Questions

Q: Hypothyroidism in Late Pregnancy: Key Concerns and Questions

Hello, <br>1. <br>If hypothyroidism is diagnosed during pregnancy, it is essential to restore thyroid function to normal as quickly as possible. <br>Adjust the T4 dosage to achieve and maintain serum thyroid-stimulating hormone (TSH) levels (using international standard measureme

Hypothyroidism discovered in the late stages of pregnancy?

Hello Doctor: I am currently 29 weeks and 2 days pregnant.
On May 19, I went to Hospital A to check my thyroid function (I had no discomfort, I just wanted to understand my condition).
On June 2, I received the following results: Free T4: 0.79 (normal range 0.89-1.76), TSH: 3.55 (normal range 0.55-4.78), Anti-TPO: 28 (<60).
The doctor informed me that I have "severe hypothyroidism," and I started taking "Eltroxin" 75 micrograms from June 3.
After hearing this result, I was very worried about the potential impact on my baby's intelligence and central nervous system, so on June 4, I went to Hospital B for another check-up.
On June 6, I received the following results: Free T4: 0.91 (normal range 0.93-1.71), TSH: 4.65 (normal range 0.27-4.2), total cholesterol: 232 (below 200), low-density lipoprotein cholesterol: 119 (below 130), triglycerides: 194 (below 150) (I have gained a total of 8.5 kg during this pregnancy).
The doctor at Hospital B informed me that I only have "mild" hypothyroidism.
Since I discovered this condition late in my pregnancy and there is not much time left for the fetus in the womb, I am deeply worried and saddened that my baby's intelligence and nervous system may have already been significantly affected.
I would like to ask you the following questions:
1.
Should TSH levels during pregnancy be below 2.5 to avoid affecting the fetus?
2.
Does my TSH increase from 3.55 (May 19) to 4.65 (June 4) indicate that my hypothyroidism is worsening?
3.
I took 19 prenatal vitamins containing 150 micrograms of iodine from May 16 to June 3; could the rapid increase in my TSH levels be related to this supplement?
4.
If so, should I avoid taking prenatal vitamins that contain iodine?
5.
Since I started medication at 28 weeks and 5 days, is there still a therapeutic effect on the fetus?
6.
Can you provide a preliminary assessment of how much the fetus may have been affected?
7.
What additional prenatal tests can be done to determine if the fetus has any abnormalities? Or should I just wait until after delivery to follow up on the baby?
8.
If the answer to the previous question is yes, what tests does the baby typically need to undergo? I learned about my hypothyroidism just a few hours after my prenatal check-up, and I wanted to ask you these questions before my next appointment.
I apologize for the numerous questions, and I appreciate your guidance.
Thank you!

Xiao Fu, 30~39 year old female. Ask Date: 2018/06/07

Dr. Zhang Kunmin reply Obstetrics and Gynecology

Hello,
1.
If hypothyroidism is diagnosed during pregnancy, it is essential to restore thyroid function to normal as quickly as possible.
Adjust the T4 dosage to achieve and maintain serum thyroid-stimulating hormone (TSH) levels (using international standard measurement methods), with recommendations of less than 2.5 mIU/liter during the first trimester (or less than 3 mIU/liter during the second and third trimesters) or according to the TSH ranges established for different stages of pregnancy.
Thyroid function should be re-evaluated within 30-40 days, and subsequent tests should be repeated every 4-6 weeks.
Prolonged low T4 levels can adversely affect fetal and neurological development.
2.
Typically, the dosage is adjusted first, and then TSH levels are monitored for changes.
3.
Due to the lack of relevant component descriptions, it is not possible to make a judgment based on this information.
4.
Hypothyroidism should be managed with adequate iodine intake.
5, 6.
It is generally recommended to control the condition early, aiming for TSH levels below 2.5 or 3.
There is insufficient data to assess the extent of the impact on your situation.
7, 8.
Currently, it is necessary to have your obstetrician and endocrinologist monitor ultrasound and thyroid function.
However, many fetal conditions cannot be fully assessed prenatally or until the child is five years old.
Thank you! Wishing you peace and health.

Dr.
Zhang

Reply Date: 2018/06/07

More Info

Hypothyroidism during pregnancy is a significant concern, especially in the later stages of gestation. Your situation, where you have been diagnosed with severe hypothyroidism and are currently on medication, raises several important questions regarding the health of both you and your baby. Let’s address your concerns one by one.

1. TSH Levels During Pregnancy: The American Thyroid Association recommends that TSH levels in pregnant women should ideally be below 2.5 mIU/L in the first trimester and below 3.0 mIU/L in the second and third trimesters. Higher levels can indicate insufficient thyroid hormone production, which may affect fetal development, particularly the brain and central nervous system.

2. Increase in TSH Levels: Your TSH level increased from 3.55 to 4.65, which could indicate worsening hypothyroidism. This is concerning, as elevated TSH levels suggest that your thyroid is not producing enough hormones to meet your body’s and your baby’s needs. It’s crucial to monitor and adjust your medication dosage accordingly.

3. Impact of Prenatal Vitamins: The prenatal vitamins you took, which contained iodine, may not directly cause an increase in TSH levels. However, excessive iodine intake can sometimes lead to thyroid dysfunction, particularly in individuals with pre-existing thyroid conditions. It’s essential to discuss with your healthcare provider whether you should continue taking iodine-containing supplements.

4. Iodine in Prenatal Vitamins: If your healthcare provider determines that your iodine intake is excessive, they may recommend avoiding additional iodine supplements. However, iodine is crucial for thyroid hormone production, so it’s important to find a balance. Always consult your doctor before making changes to your supplement regimen.

5. Effectiveness of Medication: Starting medication at 28 weeks and 5 days can still be beneficial for your baby. While the critical period for brain development occurs in the first trimester, the second and third trimesters are also important for overall growth and development. Your healthcare provider will likely monitor your thyroid levels closely and adjust your medication as needed.

6. Assessing Fetal Impact: It is challenging to determine the extent of any potential impact on the fetus without specific tests. However, if hypothyroidism is managed effectively, the risks can be minimized. Regular monitoring and appropriate treatment can help ensure better outcomes.

7. Additional Prenatal Testing: To assess the health of your baby, your healthcare provider may recommend additional ultrasounds to monitor growth and development. Blood tests can also be conducted to check for any signs of congenital issues. Genetic counseling may be beneficial if there are concerns about hereditary conditions.

8. Postnatal Assessments: After birth, your baby may undergo several tests, including a newborn screening test for congenital hypothyroidism. This is a routine procedure in many hospitals and is crucial for early detection and treatment if necessary.

In summary, managing hypothyroidism during pregnancy is crucial for the health of both you and your baby. Regular monitoring of thyroid levels, appropriate medication adjustments, and open communication with your healthcare provider are essential. If you have further concerns or experience any symptoms, do not hesitate to reach out to your doctor. Your proactive approach to understanding and managing your condition is commendable and will contribute to better outcomes for you and your baby.

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