How should I manage my TSH level while breastfeeding?

Question

Hi doctor,

I was taking Neomercazole 5 mg for the last few months, but stopped it on my own. I recently did a thyroid test. Since my TSH is still high and I am currently breastfeeding, I wanted your advice on whether I should restart any medication or adjust my treatment. My baby is 2 years 9 months old and breastfeeds only at night. Please consider this while advising about medication.

Thanks.

Answer 1

Hi,

Welcome to icliniq.com.

I can understand your concern.

Your thyroid function tests show a normal FT3 (free triiodothyronine) (3.10 pmol/L) and FT4 (free thyroxine) (1.15 pmol/L) but an elevated TSH (thyroid-stimulating hormone) (6.649 mIU/L), indicating subclinical hypothyroidism. Given you recently stopped Neomercazole (Carbimazole) and your TSH remains high, this points towards mild underactivity of the thyroid gland.

Since you are currently breastfeeding a toddler who only breastfeeds at night, treatment decisions should balance your thyroid status, medication safety, and breastfeeding continuation. Neomercazole (Carbimazole) pass into breast milk in small amounts, but at doses up to 30 mg daily, it is generally considered safe for breastfeeding infants without reported adverse thyroid effects. Infant thyroid monitoring is sometimes recommended but not mandatory if doses are low.

Your thyroid results show normal FT3 and FT4 levels with an elevated TSH, suggesting mild or subclinical hypothyroidism. Your history of hyperthyroidism treated with Neomercazole and dose reduction after breastfeeding started points to prior control of thyroid activity.

Follow the recommendations for medication while breastfeeding:

If you have no significant symptoms (other than occasional sleep problems) and your thyroid hormones are normal, restarting Neomercazole is generally not necessary, as it treats hyperthyroidism, and your laboratory tests do not suggest active hyperthyroidism.
If you are at risk of hypothyroidism after stopping the antithyroid medication (which can be possible postpartum), the usual treatment would be Levothyroxine rather than Neomercazole, as your TSH is elevated, not suppressed.
The presence of elevated TSH with normal FT3/FT4 in a breastfeeding mother often calls for careful monitoring rather than immediate treatment unless symptoms develop or TSH rises further.
Regular follow-up thyroid function tests (every six to 12 weeks) are advised to monitor TSH trends.
If hypothyroid symptoms worsen or TSH rises above 10, Levothyroxine therapy can be considered and is safe during breastfeeding.
Breastfeeding is safe during Levothyroxine or Carbimazole administration at recommended doses with minimal risk to the infant.

I hope this information will help you.

Thanks.

Answer 2

Hi,

Welcome back to icliniq.com.

I can understand your concern.

No need to take it now. You can consider it if TSH (thyroid-stimulating hormone) goes above 10 or T4 (thyroxine) becomes less than normal. You can start with 50 mcg once daily before breakfast.

I hope this information will help you.

Thanks.