General Medicine

» Elaine Moore - questionable graves disease please read!!

Hi K,
Sorry to be slow in responding.
The total T4 test measures thyroxine that's linked to protein molecules. In this form, thyroid hormone is inactive. These binding proteins (that carry hormones in the blood) are increased by estrogens and certain medications.

So the T4 level can be elevated by either increased free thyroxine or increased binding proteins. Since women can have elevated estrogens, the T4 test is often falsely increased in women. Ever since labs developed tests to measure free T4 directly with the FT4 test, we've recommended that doctors order FT4 rather than T4 levels.

Most often, when the T4 is high and TSH is normal, it's because the T4 level is falsely elevated by binding proteins. To check this, most doctors would order an FT4 level.

Another possibility is that FT4/T4 levels have risen quickly and the pituitary gland, which secretes TSH, hasn't caught up with the change. Normally, as soon as your thyroid hormone levels start to rise, the pituitary slows down or stops secreting TSH in an effort to prevent hyperthyroidism. In this way TSH regulates thyroid hormone levels. Normally, TSH would tell thyroid cells to produce more thyroid hormone. But since you mention having symptoms for 3 months, it could be that you're noticing spikes of thyroid hormone elevation. The spikes would cause symptoms but not keep your levels elevated enough to see a TSH response.

One other (rare) possibility is that you're producing TSH antibodies, not TSH receptor antibodies. TSH antibodies falsely increase the TSH test result. There are tests available to test for these antibodies. We usually run them when the thyroid function tests aren't correlating the way they should. I hope this helps.

You can also write me at the spa discussions. I tend to get there more often. Best, Elaine