Hi Elaine,

I really need your advice. I got my TSI result.

TSI: 539

Tsh: 0.017

Free T4: 0.70 (0.82-1.77)

Free T3: 4.9 (2.0-4.4)

Last year in July my TSI was 345.

I do not understand why my TSI increases when i am continuously taking medicine.

Do you think TSI is high because of my free t4 below the range. I read on your website, that "FT4 should be near the high end of the reference range, if this level can be too low for your body's needs. this causes the gland to increase its activity (always trying to protect you and preventing hypothyroidism) including an increase in the immune system cells within your gland...and this results in more thyroid antibodies."

I am taking 100 mg PTU per day. Do you think my dose is high.

Or because of this high tsi, my free t3 is high.

Also, you told in my last post that i should do block and replace but my endo is not ready to do it.
What should i do now? I am planning to start acetyl l carnitine. Anything else i can do to improve my thyroid level and antibodies.

Thank you for all the help.

Hi,
Yes, your low FT4 can easily cause a rise in your TSI level. So can any environmental trigger, including stress, allergic reactions, aspartame, chlorine, etc.

Your dose of 100 mg PTU is too high because dosing is supposed to be based on the FT4 level, always using the lowest dose needed to keep FT4 near the high end of the reference range. The high TSI can contribute to your high FT3, making it a vicious cycle. Block and replace is the best solution. Another option is to use propranolol unless your heart rate or blood pressure are low. This drug, which is a beta blocker, inhibits the conversion of T4 into T3 so it can help. Another idea is to have your doctor order an FT3 by dialysis test because the regular FT3 test can be falsely elevated by many substances, including estrogens, heterophile antibodies, etc. A result from a dialysis test may prove that FT3 is low and this may allow your doctor to lower your dose.
best, elaine