Thyroid Function During Pregnancy: Hyperthyroidism or Hypothyroidism?

Could you please provide me with your test results or specific values so I can help determine whether your thyroid function indicates hyperthyroidism or hypothyroidism?

Hello Dr.
Chen Li-Chin, I am an immunocompromised mother currently 30 weeks and 4 days pregnant.
I have autoimmune thyroiditis (anti-TPO (+), anti-TG Ab (+)).
My pregnancy TSH levels are as follows: 107/06/29 TSH 0.024, Free T4 107/06/29 14.00; 107/07/20 TSH 0.029, Free T4 107/07/20 12.50; 107/08/06 TSH 0.016, Free T4 107/08/06 11.60; 107/09/10 TSH 0.241, Free T4 107/09/10 8.44; 107/10/08 TSH 0.353, Free T4 107/10/08 7.92; 107/11/02 TSH 0.366, Free T4 107/11/02 7.87.
My doctor has prescribed 0.05 mg Eltroxin to be taken once daily on an empty stomach, but I am concerned because I believe I have hyperthyroidism, while the medication is indicated for hypothyroidism treatment.
Additionally, I would like to know if my thyroid levels, which do not appear optimal, will affect my baby after birth.
Lastly, my hemoglobin level recently dropped to 10.0; should I supplement with iron, or is dietary supplementation sufficient for now? Thank you.

C.Y., 30~39 year old female. Ask Date: 2018/11/27

Dr. Chen Liqin reply Obstetrics and Gynecology

Hello C.Y, during the second and third trimesters of pregnancy, it is recommended that TSH levels be below 3.0 mIU/L.
Therefore, during pregnancy, while free thyroid hormones are within the normal range, the thyroid-stimulating hormone (TSH) is slightly elevated, indicating mild subclinical hypothyroidism.
It is advisable for C.Y to return to the original healthcare facility to discuss medication and the status of the fetus with the physician.
It is also normal for hemoglobin levels to be lower during pregnancy, so a balanced diet and regular follow-up appointments are recommended.

Reply Date: 2018/11/27

More Info

Understanding thyroid function during pregnancy is crucial, as both hyperthyroidism and hypothyroidism can significantly impact maternal and fetal health. In your case, you have autoimmune thyroiditis, which can complicate the management of thyroid hormone levels during pregnancy.
From the data you provided, your TSH levels have fluctuated, with some readings indicating low TSH (which suggests hyperthyroidism) and others indicating higher levels. The Free T4 levels also show variability, which is important to monitor. In pregnancy, the normal range for TSH is typically lower than in non-pregnant individuals, but a TSH level below 0.1 mIU/L is often considered indicative of hyperthyroidism. Your recent TSH levels suggest that you may be experiencing some degree of hyperthyroidism, which can lead to complications such as preterm birth, low birth weight, and developmental issues in the child.

Your physician has prescribed Eltroxin (levothyroxine), which is typically used to treat hypothyroidism. This may seem counterintuitive, but in cases of autoimmune thyroiditis, the goal is to stabilize thyroid hormone levels. The medication helps to provide the necessary thyroid hormone that your body may not be producing adequately, especially during the increased demands of pregnancy. It is essential to maintain a balance; too much thyroid hormone can lead to hyperthyroidism, while too little can lead to hypothyroidism, both of which can adversely affect your health and that of your baby.

Regarding your concern about the impact on your baby, it is essential to maintain optimal thyroid function throughout your pregnancy. Uncontrolled thyroid dysfunction can lead to developmental issues, including cognitive impairments. However, with proper management and monitoring, many women with thyroid conditions have healthy pregnancies and babies. Regular follow-ups with your healthcare provider, including endocrinologists who specialize in thyroid disorders, are crucial to ensure that your hormone levels remain stable.

As for your hemoglobin level dropping to 10.0, this indicates mild anemia, which is common during pregnancy due to increased blood volume and the body's higher demand for iron. It is advisable to discuss iron supplementation with your healthcare provider. While dietary changes can help, such as increasing your intake of iron-rich foods (like red meat, leafy greens, and legumes), you may also need iron supplements to restore your levels effectively.
In summary, managing thyroid function during pregnancy is vital for both maternal and fetal health. Regular monitoring of TSH and Free T4 levels, adherence to prescribed medications, and addressing any nutritional deficiencies, such as iron, will help ensure a healthy pregnancy outcome. Always consult with your healthcare provider for personalized advice and treatment plans tailored to your specific situation.

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