The Fact
A study in the New England Journal of Medicine checked postmenopausal women with hypothyroidism who were taking thyroid hormone (thyroxine) before and after they started estrogen, every six weeks for 48 weeks. In 7 of the 18 women on standard thyroxine treatment, the thyroid-stimulating hormone (TSH) level rose above 7, a sign they needed a higher thyroid dose. The author concluded that women with hypothyroidism may need more thyroxine when they take estrogen.
What This Means
Your hormones work as a team. A woman on thyroid medicine who starts or stops estrogen may need her thyroid levels rechecked — the dose that worked before may not fit anymore.
Sources
- Arafah, Baha M. “Increased need for thyroxine in women with hypothyroidism during estrogen therapy.” New England Journal of Medicine 344, no. 23 (2001): 1743–1749.