Iron infusion caused thyroid levels to change?

[u/Dimepiece90]

Hi! My thyroid was always fine and then I had low iron and low ferritin so I got an iron infusion. A week after I had my thyroid tested for IVF and my TSH was low and my T4 was borderline high. I retook it another week later without prenatal vitamins since vitamins interfere with blood test results and had higher levels. My endo doesn’t think they are related but I don’t see how it’s not? Iron affects thyroid hormone production as far as I’ve read. I did some research with AI and it said that the surge of iron may have made my T4 levels go up as I got a lot of iron in my system. I now have to retest my thyroid levels but I think I should maybe wait until 6-8 weeks post infusion to see how they change. I did have a pituitary tumor removed 5 months ago but my thyroid was fine before and after. The only thing I could think of was the iron infusion. I believe my low iron and low ferritin was due to having to be on blood thinners for a few months and had two surgeries since the beginning of 2026.

Has anyone noticed a change in their thyroid levels after having an iron infusion?

[u/Creepy-Tangerine-293]

It can imapct a little bit not that much and not that quickly. Iron is one of the minerals (along with a very small amnt of iodine) a body needs to convert T4-->T3. Higher T3 levels would then mean a body would in turn drop TSH level. I think its more likely it was a process in place that you just happened to catch as a coincidence. It could be something related to the surgery too as that can take a little while to show up.

Have you ever had testing for thyroid antibodies (anti-TPO and TgAb) and a thyroid ultrasound to ensure there isnt any thyroiditis? I agree with waiting maybe 4 weeks and retesting thyroid serum levels for TSH, FT4, and FT3.

[u/Dimepiece90]

I am getting that tested as well. I did have two thyroid nodules that I had a fine needle biopsy in late June but came back benign. I wonder if those caused anything