HSG and iodine induced hyperthyrodism

[jeremy33]

Hi,
I was sent for a hysterosalpingogram (HSG) after my miscarriage. The HSG uses an iodine contrast dye that is injected into the uterus. My gyn is aware that I have Grave disease and am allergy to shellfish. I was euthyroid before the HSG procedure. 2 weeks after the HSG, my TSH decreased from 1.47 to 0.04. My Ft4 and Ft3 increase from mid range to the upper range.  
My question is does HSG trigger a new episode of grave disease? When I confronted my gyn, I was told that the iodine in HSG is very little compared to those high doses of contrast dye for CT scan (iodine injected into the blood vessel). How true is this? I read from the web that euthyroid patients previously treated with antithyroid drugs for Graves' disease are prone to develop iodine-induced hyperthyroidism. How high is the iodine content in HSG and can this affect the thyroid?
If HSG can affect the thyroid, why am I sent for this risky procedure since I have Grave disease?

[Mark Lupo, M.D.]

I do not know the actual iodine content for the average HSG, but any excess iodine could trigger a problem, but fortunately this is not common.  Once the iodine clears the system, the thyroid may return to normal (may take 1-3 months) but in patients with hyperthyroidism (from graves or toxic nodules) we sometimes pre-treat with tapazole before iodine-contrast procedures.  However w/ your normal baseline TSH, the standard of care would not likely have been to pre-treat with tapazole.

[jeremy33]

Many thanks for your reply and explanation. I am very dissapointed with my gyn for recommending this HSG procedure which is used to chk for tube blockage. I got pregnant and miscarriage and dun see the need for this risky procedure. And further more i have Grave disease and is allergy to shellfish. I think some doctors are just out there to make money.

People out there, pls reconsider and do your homework before rushing into any treatment.